Comparison of Particulate Air Pollution From Different Emission Sources and Incident Dementia in the US

Long-term exposure to dust in fine particulate matter and post-stroke functional impairment-Findings from the China National Stroke Screening Surveys

The dust component of particulate matter (PM) warrants more attention in the era of climate change and increased frequency of dust event, yet rarely are studies focused exclusively on the long-term health effects of dust PM2.5. This study aims to assess the relative toxicity of dust and non-dust PM2.5 on the long-term functional impairment after stroke. We utilized data from a multicenter, national survey in China from 2013 to 2019 and selected participants with repeated assessments of the functional impairment outcomes, the modified Rankin scale (mRS) score, to form a longitudinal dataset. The dust PM2.5 exposure data were constructed by combining multiple sources and of high spatial resolution. Fixed effect models were used to estimate the association between dust PM2.5 exposure and changes in mRS scores. A two-dimensional spline model was used to model the joint effect of dust and non-dust PM2.5 exposure. We included 28,081 participants (65,883 visits). Per interquartile range increase of the dust PM2.5 was associated with 0.048 (95 % confidence interval [CI]: 0.003-0.092) increase in mRS score. Results of co-exposure to dust and non-dust PM2.5 showed that the greater the proportion of dust PM2.5 was, the stronger the combined effect. This study revealed that long-term exposure to dust PM2.5 was associated with post-stroke functional impairment. More studies on the long-term effects of dust and dust-sourced PM2.5 on neurological outcomes are warranted in the future.

A systematic review of air pollution exposure and brain structure and function during development

OBJECTIVES

Air pollutants are known neurotoxicants. In this updated systematic review, we evaluate new evidence since our 2019 systematic review on the effect of outdoor air pollution exposure on childhood and adolescent brain structure and function as measured by magnetic resonance imaging (MRI).

METHODS

Using PubMed, Web of Science, and Scopus we conducted an updated literature search and systematic review of articles published through January 2025, using key terms for air pollution and functional and/or structural MRI. Two raters independently screened all articles using Covidence and implemented the risk of bias instrument for systematic reviews used to inform the World Health Organization Global Air Quality Guidelines.

RESULTS

We identified 29 relevant papers, and 20 new studies met our inclusion criteria. Including six studies from our 2019 review, the 26 publications to date include study populations from the United States, Netherlands, Spain, and United Kingdom. Studies investigated exposure periods spanning pregnancy through early adolescence, and estimated air pollutant exposure levels via personal monitoring, geospatial residential estimates, or school courtyard monitors. Brain MRI occurred when children were on average 6-14.7 years old; however, one study assessed newborns. Several MRI modalities were leveraged, including structural morphology, diffusion tensor imaging, restriction spectrum imaging, arterial spin labeling, magnetic resonance spectroscopy, as well as resting-state and task-based functional MRI. Air pollutants were associated with widespread brain differences, although the magnitude and direction of findings are largely inconsistent, making it difficult to draw strong conclusions.

CONCLUSION

Prenatal and childhood exposure to outdoor air pollution is associated with structural and functional brain variations. Compared to our initial 2019 review comprised of only cross-sectional studies, the current literature now includes longitudinal studies and more advanced neuroimaging methods. Further research is needed to clarify the effects of developmental timing, along with the downstream implications of outdoor air pollution exposure on children's cognitive and mental health.

Sources and components of fine air pollution exposure and brain morphology in preadolescents

Air pollution is an emerging novel neurotoxicant during childhood and adolescence. However, little is known regarding how fine particulate matter (PM2.5) components and its sources impact brain morphology. We investigated air pollution exposure-related differences in brain morphology using cross-sectional magnetic resonance imaging data from 10,095 children ages 9-11 years-old enrolled in the United States' Adolescent Brain Cognitive Development Study [2016-2018]. Air pollution estimates included fifteen PM2.5 constituent chemicals and metals, and six major sources of PM2.5 (e.g., crustal materials, biomass burning, traffic) identified from prior source apportionment, as well as nitrogen dioxide (NO2) and ozone (O3). After adjusting for demographic, socioeconomic, and neuroimaging covariates, we used partial least squares analyses to identify associations between simultaneous co-exposures and morphological differences in cortical thickness, surface area, and subcortical volumes. We found that greater exposure to PM2.5 and NO2 was associated with decreases in frontal and increases in inferior temporal surface area. PM2.5 component and source analyses linked cortical surface area and thickness to biomass burning (e.g., organic carbon, potassium), crustal material (e.g., calcium, silicon), and traffic (e.g., copper, iron) exposures, while smaller subcortical volumes were linked to greater potassium exposure. This is the first study to show differential effects of several air pollution sources on development of children's brains. Significant associations were found in brain structures involved in several cognitive and social processes, including lower- and higher-order sensory processing, socioemotional behaviors, and executive functioning. These findings highlight differential effects of several air pollution sources on brain structure in preadolescents across the U.S.

Effect of operating conditions and technology on residential wood stove emissions of criteria, greenhouse gas, and hazardous air pollutants

Residential wood heating (RWH) is a known source of particulate matter (PM), hazardous air pollutants (HAPs), and greenhouse gases (GHGs). However, the influence of operating conditions on emissions from certified cordwood stoves in the United States (U.S.) remains poorly understood. This study analyzes emissions data from different operational phases, including start-up, high heat, and low heat, to improve indicators of real-world stove performance. We tested five commercially available U.S. stoves through the four distinct operational conditions or phases of the novel Integrated Duty Cycle (IDC) testing protocol, which simulates typical residential wood-burning patterns by incorporating start-up, high heat, medium (or "maintain") heat, and low heat ("overnight" burn) phases. We determined emissions factors (EFs) by IDC phase for criteria, GHG, and HAP compounds, including volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). We also developed a multiple linear regression model to assess the effect of dry burn rate (DBR) and IDC phase on each pollutant EF by stove technology type. IDC phase significantly influenced (p < 0.01) pollutant EFs from uncertified stoves and most emissions from catalytic/hybrid stoves, while DBR played a more substantial role in emissions from non-catalytic stoves. Current stove certification methods rely on a single nominal load under steady-state combustion, which does not reflect typical residential use. Additionally, we found DBR to be an inconsistent predictor of emissions in cordwood stoves. These findings underscore the importance of stove technology and operating conditions in determining RWH emissions, with implications for air quality science and regulatory policy.Implications: We report cordwood stove emissions factors by operating condition using the novel Integrated Duty Cycle (IDC) protocol on various U.S. technologies meeting 2020 New Source Performance Standards (NSPS) and one pre-NSPS, circa 1980 stove. We determined significant effects from IDC operating phase on uncertified and catalytic/hybrid stove emissions, but not noncatalytic stoves. This has important implications for use of emissions factors in air quality science, policy, and stove design, as different U.S. climate zones will influence the number of stove start-ups, fuel loading patterns, and frequencies of other "real world" operating conditions such as "high heat" and "overnight burn."

The role of the components of PM2.5 in the incidence of Alzheimer's disease and related disorders

BACKGROUND

The associations of PM2.5 mass and various adverse health outcomes have been widely investigated. However, fewer studies focused on the potential health impacts of PM2.5 components, especially for dementia and Alzheimer's diseases (AD).

METHODS

We constructed a nationwide population-based open cohort study among Medicare beneficiaries aged 65 or older during 2000-2018. This dataset was linked with the predicted levels of 15 PM2.5 components, including 5 major mass contributors (EC, OC, NH4+, NO3-, SO42-) and 10 trace elements (Br, Ca, Cu, Fe, K, Ni, Pb, Si, V, Zn) across contiguous U.S. territory. Data were aggregated by ZIP code, calendar year and individual level demographics. Two mixture analysis methods, weighted quantile sum regression (WQS) and quantile g-computation (qgcomp), were used with quasi-Poisson models to analyze the health effects of the total mixture of PM2.5 components on dementia and AD, as well as the relative contribution of individual components.

RESULTS

Exposure to PM2.5 components over the previous 5 years was significantly associated with increased risks of both dementia and AD, with stronger associations observed for AD. SO42-, OC, Cu were identified as major contributors to the combined positive association of the mixture from both WQS and qgcomp models.

CONCLUSION

We found positive associations between the 15 PM2.5 components and the incidence of dementia and AD. Our findings suggest that reducing PM2.5 emissions from traffic and fossil fuel combustion could help mitigate the growing burden of dementia and Alzheimer's disease.

Atmospheric Pollutants, Cardiometabolic Disorders, and Dementia in Trajectory Analysis: A 13-Year Longitudinal Cohort Study

BACKGROUND

First cardiometabolic disorders (FCMDs) and dementia pose a significant burden on aging populations. Investigating the association between atmospheric pollutants and the progression of FCMDs and dementia is crucial.

METHODS

A prospective analysis was conducted on 413 149 participants from the UK Biobank. Atmospheric pollutant concentrations were calculated using land-use regression models. We used a multistate model and calculated the polygenic risk score for dementia to analyze the associations of pollutants on the relevant trajectories from baseline to FCMD, subsequent dementia, and death.

RESULTS

Over 13 years, 65 336 patients with FCMD were identified, with 2584 developing dementia and 10 664 dying. Each interquartile range increase in pollutant concentrations showed the hazard ratios (HRs) of particulate matter with aerodynamic diameter ≤2.5 μm (HR, 1.03 [95% CI, 1.02-1.05]); nitrogen dioxide (HR, 1.04 [95% CI, 1.03-1.05]), and nitrogen oxides (HR, 1.03 [95% CI, 1.02-1.04]) for transitioning from baseline to FCMD; particulate matter with aerodynamic diameter ≤2.5 μm (HR, 1.11 [95% CI, 1.05-1.16]; nitrogen dioxide: HR, 1.12 [95% CI, 1.06-1.18]; and nitrogen oxides (HR, 1.07 [95% CI, 1.03-1.12]) for transitioning from FCMD to dementia, and the association between pollutants and this trajectory remained consistent after adjusting for genetic susceptibility to dementia (particulate matter with aerodynamic diameter ≤2.5 μm: HR, 1.06 [95% CI, 1.04-1.08]; nitrogen dioxide: HR, 1.05 ([95% CI, 1.03-1.07); and nitrogen oxides: HR, 1.05 [95% CI, 1.03-1.06]) for transitioning from baseline to death; and particulate matter with aerodynamic diameter ≤2.5 μm: HR, 1.03 ([95% CI, 1.00-1.05); nitrogen dioxide: HR, 1.05 ([95% CI, 1.02-1.08); nitrogen oxides: HR, 1.04 ([95% CI, 1.01-1.06]) for transitioning from subsequent FCMD to death. Particulate matter with aerodynamic diameter ≤10 μm was only significantly associated with the transition from baseline to FCMD.

CONCLUSIONS

Our study provides the first evidence that atmospheric pollutants are associated with the progression of FCMD and subsequent dementia.

Spatiotemporal variations and inequalities in global traffic-sourced PM2.5 exposure

Traffic emission is a major source of ambient fine particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) pollution. However, little is known about the global population exposure to traffic-sourced PM2.5 at high spatiotemporal resolutions. This study, utilizing chemical transport and machine learning models, estimated global daily traffic-sourced PM2.5 at a 0.25° × 0.25° spatial resolution during 2000-2019. The results showed that global population-weighted average traffic-sourced PM2.5 concentrations increased, aligning with the trend in total PM2.5 concentrations, rising from 5.8 µg/m3 (contributing to 15.3 % of global total PM2.5) in 2000-2009 to 6.6 µg/m3 (16.4 % of total PM2.5) in 2010-2019. Our analysis showed that the increasing trend of traffic-sourced PM2.5 contributed 36.0 % to the global increasing trend of total PM2.5. The increasing traffic-sourced PM2.5 were primarily in Asia, while Europe, North America, and Oceania experienced decreasing trends. Higher concentrations or proportions of traffic-sourced PM2.5 generally occur during colder months, especially in Asia, and in countries with higher socioeconomic levels. The top ten countries with the highest traffic PM2.5 proportion in both decades are all high-income countries. Inequalities existed both between and within countries/territories assessed by the Gini index. Compared to total PM2.5 exposure, traffic-sourced PM2.5 exposure demonstrated greater inequalities at the global level, within and between countries. Our study provides essential data for identifying high-risk traffic-related PM2.5 exposure areas, assessing regional pollution control effectiveness, exploring health impacts, and promoting environmental justice.

Challenges in studying air pollution to neurodegenerative diseases

Exposure to ambient air pollution is ubiquitous and unavoidable. While associations between air pollution and cardiometabolic diseases are well-established, its role in neurodegenerative diseases, such as Alzheimer's disease and related dementias (ADRD) and Parkinson's disease (PD), has only recently begun to emerge. This narrative review provides an overview of current findings and discusses challenges and opportunities for future epidemiologic research. Mechanistically, air pollution may contribute to ADRD and PD through neuroinflammation, oxidative stress, and cerebrovascular damage. Long-term exposure to high levels of air pollution may increase the risk of ADRD and PD. Over the past 20 years, more than 50 studies have examined air pollution and ADRD, while fewer studies have focused on PD. Although the estimated effects are modest in size, they translate into a substantial number of affected individuals due to the widespread nature of the exposure and an increasingly aging population worldwide. Future research should extend exposure periods to cover younger and middle ages, estimate the effects of long-term cumulative exposures, and evaluate moderators and mediators, such as diet, physical activity, green space, and noise. More studies are also needed to include large and diverse populations, including those with special vulnerabilities and emerging exposures like wildfire smoke.

Sleep and Arousal Hubs and Ferromagnetic Ultrafine Particulate Matter and Nanoparticle Motion Under Electromagnetic Fields: Neurodegeneration, Sleep Disorders, Orexinergic Neurons, and Air Pollution in Young Urbanites

Air pollution plays a key role in sleep disorders and neurodegeneration. Alzheimer's disease (AD), Parkinson's disease (PD), and/or transactive response DNA-binding protein TDP-43 neuropathology have been documented in children and young adult forensic autopsies in the metropolitan area of Mexico City (MMC), along with sleep disorders, cognitive deficits, and MRI brain atrophy in seemingly healthy young populations. Ultrafine particulate matter (UFPM) and industrial nanoparticles (NPs) reach urbanites' brains through nasal/olfactory, lung, gastrointestinal tract, and placental barriers. We documented Fe UFPM/NPs in neurovascular units, as well as lateral hypothalamic nucleus orexinergic neurons, thalamus, medullary, pontine, and mesencephalic reticular formation, and in pinealocytes. We quantified ferromagnetic materials in sleep and arousal brain hubs and examined their motion behavior to low magnetic fields in MMC brain autopsy samples from nine children and 25 adults with AD, PD, and TDP-43 neuropathology. Saturated isothermal remanent magnetization curves at 50-300 mT were associated with UFPM/NP accumulation in sleep/awake hubs and their motion associated with 30-50 µT (DC magnetic fields) exposure. Brain samples exposed to anthropogenic PM pollution were found to be sensitive to low magnetic fields, with motion behaviors that were potentially linked to the early development and progression of fatal neurodegenerative diseases and sleep disorders. Single-domain magnetic UFPM/NPs in the orexin system, as well as arousal, sleep, and autonomic regions, are key to neurodegeneration, behavioral and cognitive impairment, and sleep disorders. We need to identify children at higher risk and monitor environmental UFPM and NP emissions and exposures to magnetic fields. Ubiquitous ferrimagnetic particles and low magnetic field exposures are a threat to global brain health.

Cognitive Performance and Long-term Exposure to Outdoor Air Pollution: Findings From the Harmonized Cognitive Assessment Protocol Substudy of the English Longitudinal Study of Ageing (ELSA-HCAP)

BACKGROUND

Although air pollution is associated with worse cognitive performance, whether these relationships differ by cognitive domain and which sources of air pollution are particularly detrimental to cognition remains understudied. This study examined associations between cognitive scores across 3 domains in older adults and 8-10 years of exposure to air pollutants (NO2, total PM2.5, and PM2.5 from different emission sources).

METHODS

We used data from the 2018 Harmonized Cognitive Assessment Protocol substudy of the English Longitudinal Study of Ageing (N = 1 127). Outdoor concentrations of each pollutant were estimated for 2008/2010-2017 and summarized using means and group-based trajectories. Linear regression models were used to assess long-term air pollution exposure relationships with memory, executive function, language, and global cognitive function after adjustment for key individual and neighborhood-level confounders.

RESULTS

Associations between air pollution trajectories and cognition are mostly inverted j-shaped, with respondents exposed to the highest residential levels of NO2 and total PM2.5 having worse performance for global cognition (β = -.241; 95% CI = [-0.46, -0.02] and β = -.334; 95% CI = [-0.55, -0.12], respectively) than those exposed to average levels of pollution. Similar associations were also found for executive function and memory (PM2.5 only), whereas more compelling dose-response evidence was found for language. Higher emissions from industry and residential combustion, as well as biofuel, coal, and oil and natural gas combustion, were associated with worse language scores.

CONCLUSIONS

Air pollution and its sources have domain-specific associations with cognitive performance, with most consistent evidence observed for language. Continued efforts to reduce air pollution, particularly where levels are the highest, might benefit cognitive performance.

Five-month real-ambient PM2.5 exposure impairs learning in Brown Norway rats: Insights from multi omics-based analysis

PM2.5, recognized as a potential pathogenic factor for nervous system diseases, remains an area with many unknowns, particularly regarding its effects on human health. After five-month real-ambient PM2.5 exposure, we observed no significant pathological damage to the lung, liver, spleen, or kidney tissues. However, PM2.5 exposure led to neuronal degeneration in the hippocampal CA1 region of Brown Norway (BN) rats. The level of IL-6, IL-13, IL-1β, IL-12, IL-4, GRO/KC, MIP-1α, CM-CSF significantly increased in lung lavage fluid (P < 0.05 for all). Notably, we detected a slight impairment in spatial learning ability, as evidenced by the Barnes maze training outcomes. There were no significant changes in the bacterial community in lung lavage fluid (P = 0.621), but the bacterial community in the gut significantly changed (P < 0.001), with more species identified (P < 0.05). The metabolomic analysis revealed 147 and 149 significantly changed metabolites in the pulmonary system and serum, respectively (P < 0.05). PM2.5 exposure caused a decrease in Nervonic acid (NA) in both the lung and serum, which likely contributed to spatial learning impairment (P < 0.01). The correlation between lung metabolites, gut bacterial species, and serum metabolites indicated that PM2.5 exposure likely impaired spatial learning through the lung-gut-brain axis pathway. Lung and serum metabolic disorders and intestinal microbial imbalance occurred in BN rats post-five-month real-ambient PM2.5 exposure. There were two potential ways that PM2.5 exposure caused the decline of spatial learning ability in wild-type BN rats: (1) PM2.5 exposure led to a significant decrease of neuroprotective Nervonic acid in lung and serum metabolites. (2) PM2.5 exposure likely led to reduced spatial learning ability through the lung-gut-brain axis.

Estimating the Effects of Hypothetical Ambient PM2.5 Interventions on the Risk of Dementia Using the Parametric g-Formula in the UK Biobank Cohort

BACKGROUND

Emerging evidence identifies ambient particulate matter (PM) with an aerodynamic diameter ≤ 2.5 μ m (PM 2.5 ) as a modifiable risk factor for dementia, but the potential health benefits gained by enacting regulations that reduce PM 2.5 remain unclear.

OBJECTIVES

Our aim was to estimate the total effects of hypothetical ambient PM 2.5 interventions starting in late life on the risk of dementia in a cohort using the parametric g-formula.

METHODS

We used data from 291,495 participants in the UK Biobank cohort who were free of dementia and ≥ 55 y of age at baseline (2010). We estimated the total effects of hypothetical ambient PM 2.5 interventions (achieving annual average standards of 12   μ g / m 3 , 10   μ g / m 3 , and 9   μ g / m 3 ) from 2010 to 2019 on the risk of dementia by calculating the difference between the estimated 10-y risk of dementia under a specified hypothetical intervention and the risk under no intervention using the parametric g-formula.

RESULTS

In comparison with no intervention, the estimated 10-y risk difference of dementia was - 0.54 per 1,000 population [95% confidence interval (CI): - 1.00 , - 0.10 ], - 1.36 per 1,000 population (95% CI: - 2.44 , - 0.25 ), - 1.92 per 1,000 population (95% CI: - 3.39 , - 0.33 ), with PM 2.5 interventions achieving annual average standards of 12   μ g / m 3 , 10   μ g / m 3 , and 9   μ g / m 3 , respectively.

DISCUSSION

The estimated 10-y risk of dementia decreased if the individual ambient PM 2.5 exposure was reduced due to more stringent PM 2.5 standards in late life in comparison with the natural course without intervention on ambient PM 2.5 exposure. Our findings, obtained using the parametric g-formula-a causal inference method that can directly evaluate the impact of hypothetical interventions-suggest that policies reducing ambient PM 2.5 pollution may lower the risk of dementia among UK Biobank participants who would experience more stringent ambient PM 2.5 standards in late life. https://doi.org/10.1289/EHP14723.

Long-Term Exposure to PM2.5 Constituents, Genetic Susceptibility, and Incident Dementia: A Prospective Cohort Study among 0.2 Million Older Adults

Fine particulate matter, known as PM2.5, is recognized as a risk factor for dementia. However, the specific linkage between PM2.5 constituents and dementia is not well understood. We conducted a cohort of 217,336 participants of the UK Biobank to explore the association of long-term exposure to PM2.5 constituents with all-cause dementia, Alzheimer's disease (AD), and vascular dementia. We estimated PM2.5 constituents based on residential addresses by an evaluation model and used time-varying Cox models and Quantile g-computation models to assess the effects of individual constituents and their mixtures. Genetic susceptibility to dementia was assessed using a polygenic risk score, and its multiplicative and additive interactions with PM2.5 constituents were analyzed. Our results showed that black carbon (BC), ammonium (NH4+), organic matter (OM), and sulfate (SO42-) were positively associated with all-cause dementia, while BC and OM were linked to AD, with BC being the most influential. The combined effect of PM2.5 constituents and genetic risk was stronger than their individual effect. This study offers new insights into the association between PM2.5 constituents and dementia, especially those from fuel combustion and automobile exhaust, and highlights the need for effective prevention strategies.

Discarded intravenous medication in the ICU: the GAME-OVER multicenter prospective observational study

BACKGROUND

Medication waste is a contributor to the healthcare environmental footprint and impacts ecosystems. Data on medication waste in the intensive care unit (ICU) are scarce, and therefore are essential to develop new sustainable strategies.

METHODS

The GAME-OVER French multicenter prospective observational study was conducted from November 2022 to March 2023, over a 24-h period of choice, at the discretion of each participating center. Adult ICUs were enrolled in the study on a voluntary basis and hospitalized patients who did not express opposition were included in the analysis. The primary endpoint was the percentage of discarded intravenous (IV) medication in the ICU, defined as the ratio of the discarded volume to the total volume of IV medication prepared. Secondary endpoints included identifying risk factors and main reasons for medication waste and estimating its related healthcare cost.

RESULTS

Among the 81 ICUs and the 1076 enrolled patients, 408.9 L of 130 IV medications were prepared. The discarded volume was 43.8 L, resulting in a 10.7% discarded IV medication (95% Confidence Interval (CI), 9.9-11.5). Number of daily admissions/discharges in the ICU, as admission for elective surgery, Sequential Organ Failure Assessment score ≥ 7, endotracheal intubation, renal replacement therapy and body mass index were independently associated with increased discarded IV medication. Ninety percent of pharmaceutical waste was attributed to 25 key drugs, with an estimated national annual cost of 2,737,163€.

CONCLUSIONS

Discarded intravenous medication in the ICU is considerable and results in significant costs for the health care system, without obvious patient-centered value. Risk factors associated with medication waste were largely nonmodifiable, emphasizing the need for sustainable practices in patient care and resource management.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05553054 . September 23, 2022.

Shifting the Conversation on Wildland Fire Smoke Exposures: More Smoke Within and Across Years Requires a New Approach to Inform Public Health Action

With the increase in acres burned from wildfire over the last few decades, wildfire smoke is an increasing global public health threat. To date, wildfire smoke research, risk communication, and public health action has focused on short-term (or daily) smoke exposures. However, the patterns of wildfire smoke exposure are transitioning to include longer duration and repeated exposures occurring within and across years. Epidemiologic and experimental studies represent important lines of evidence that have informed risk communication and public health actions for short-term smoke exposures; however, they have yet to provide the science needed to refine public health approaches to include other dynamic exposure durations such as repeated, episodic, or cumulative. This commentary provides an overview of methodological approaches used and recent findings from epidemiologic and experimental studies that examined longer duration, repeated smoke exposures. Based on the current science, we recommend that future epidemiologic and experimental studies of wildfire smoke examine multiple exposure metrics to capture the duration, frequency, and intensity of exposures. Such studies would improve the science produced to best support the needs of the public as we strive to further protect public health in a world projected to have more smoke.

Wildfire Smoke Exposure and Incident Dementia

Importance

Long-term exposure to total fine particulate matter (PM2.5) is a recognized dementia risk factor, but less is known about wildfire-generated PM2.5, an increasingly common PM2.5 source.

Objective

To assess the association between long-term wildfire and nonwildfire PM2.5 exposure and risk of incident dementia.

Design, Setting, and Participants

This open cohort study was conducted using January 2008 to December 2019 electronic health record (EHR) data among members of Kaiser Permanente Southern California (KPSC), which serves 4.7 million people across 10 California counties. KPSC members aged 60 years or older were eligible for inclusion. Members were excluded if they did not meet eligibility criteria, if they had a dementia diagnosis before cohort entry, or if EHR data lacked address information. Data analysis was conducted from May 2023 to May 2024.

Exposures

Three-year rolling mean wildfire and nonwildfire PM2.5 in member census tracts from January 2006 to December 2019, updated quarterly and estimated via monitoring and remote-sensing data and statistical techniques.

Main Outcome and Measures

The primary outcome was incident dementia, identified using diagnostic codes in the EHR. Odds of dementia diagnoses associated with 3-year mean wildfire and nonwildfire PM2.5 exposure were estimated using a discrete-time approach with pooled logistic regression. Models adjusted for age, sex, race and ethnicity (considered as a social construct rather than as a biological determinant), marital status, smoking status, calendar year, and census tract-level poverty and population density. Stratified models assessed effect measure modification by age, sex, race and ethnicity, and census tract-level poverty.

Results

Among 1.64 million KPSC members aged 60 years or older during the study period, 1 223 107 members were eligible for inclusion in this study. The study population consisted of 644 766 female members (53.0%). In total, 319 521 members identified as Hispanic (26.0%), 601 334 members identified as non-Hispanic White (49.0%), and 80 993 members received a dementia diagnosis during follow-up (6.6%). In adjusted models, a 1-μg/m3 increase in the 3-year mean of wildfire PM2.5 exposure was associated with an 18% increase in the odds of dementia diagnosis (odds ratio [OR], 1.18; 95% CI, 1.03-1.34). In comparison, a 1-μg/m3 increase in nonwildfire PM2.5 exposure was associated with a 1% increase (OR, 1.01; 95% CI, 1.01-1.02). For wildfire PM2.5 exposure, associations were stronger among members less than 75 years old upon cohort entry, members from racially minoritized subgroups, and those living in high-poverty vs low-poverty census tracts.

Conclusions and Relevance

In this cohort study, after adjusting for measured confounders, long-term exposure to wildfire and nonwildfire PM2.5 over a 3-year period was associated with dementia diagnoses. As the climate changes, interventions focused on reducing wildfire PM2.5 exposure may reduce dementia diagnoses and related inequities.

Exposure duration and cerebral amyloidosis in the olfactory cortex of World Trade Center responders: A positron emission tomography and magnetic resonance imaging study

BACKGROUND

Amyloid-β proteins, a hallmark of Alzheimer's disease, are believed to play an adaptive role in the cerebral immune response.

OBJECTIVE

Amyloid is believed to play a role in cerebral immune response and could play a similar role in response to air pollution exposures. In the present study, we examined whether WTC exposure duration was associated with cerebral amyloidosis in WTC responders.

METHODS

WTC responders (aged 44-65 years) who varied in exposure duration but did not use personalized protective equipment were assessed using positron-emission tomography with [18F]-Florbetaben. The outcome was the cortical [18F]-Florbetaben burden, measured using regional standardized uptake value ratios (SUVRs) in 34 Desikan-Killiany regions of interest. Spearman's ρ and generalized linear models were used to estimate correlations between WTC exposure duration and cortical [18F]-Florbetaben SUVR. Cognitive and behavioral symptoms were measured. Magnetic resonance imaging was used to measure cortical thickness and diffusivity.

RESULTS

The mean age of imaged responders was 56 years old. WTC exposure duration was associated with olfactory [18F]-Florbetaben SUVR (Spearman's ρ = 0.43, p = 0.011), which was in turn associated with elevated [18F]-Florbetaben SUVR in ventral regions (ρ = 0.41, p = 0.016). Cortical [18F]-Florbetaben in ventral regions was associated with reduced response speed (ρ = -0.72, p < 0.001), was co-located with cortical diffusivity across regions in the parietal and frontal lobes and reduced cortical thickness in the isthmus cingulate (ρ = -0.53, p = 0.001).

CONCLUSIONS

Low-grade amyloidosis in the olfactory and frontal lobes was associated with WTC exposure duration. Future work should examine whether low-grade amyloidosis is correlated with the location or distribution of neurofibrillary tangles in WTC responders.

Aspirin-triggered resolvin D1 modulates pulmonary and neurological inflammation in an IL-22 knock-out organic dust exposure mouse model

Agriculture dust contains many organic immunogenic compounds, and organic dust exposure is strongly associated with the development of immune-mediated chronic pulmonary diseases such as chronic obstructive pulmonary disease (COPD). Chronic organic dust exposure from agriculture sources induces chronic lung inflammatory diseases and organic dust exposure has recently been linked to an increased risk of developing dementia. The cytokine interleukin-22 (IL-22) has been established as an important mediator in the resolution and repair of lung tissues. The omega-3 fatty acid metabolite aspirin-triggered Resolvin D1 (AT-RvD1) has shown efficacy in modulating the immune response in both pulmonary and neurological inflammation but has not been explored as a therapeutic in organic dust exposure-induced neuroinflammation. Investigating the link between IL-22 and AT-RvD1 may help in developing effective therapies for these immune-mediated diseases. We aimed to investigate the link between organic dust exposure and neuroinflammation, the role of IL-22 in the pulmonary and neurological immune response to organic dust exposure, and the immune-modulating therapeutic applications of AT-RvD1 in an IL-22 knock-out mouse model of organic dust exposure. C57BL/6J (WT) and IL-22 knock-out (KO) mice were repetitively exposed to aqueous agriculture organic dust extract (DE) 5 days per week for 3 weeks (15 total instillations) and treated with AT-RvD1 either once per week (3 total injections) or 5 times per week (15 total injections) for 3 weeks and allowed to recover for 3 days. We observed a significant pulmonary and neurological immune response to DE characterized by the development of inducible bronchus associated lymphoid tissue in the lung and gliosis in the frontal areas of the brain. We also observed that IL-22 knock-out increased pulmonary and neurological inflammation severity. Animals exposed to DE and treated with AT-RvD1 displayed reduced lung pathology severity and gliosis. Our data demonstrate that DE exposure contributes to neurological inflammation and that IL-22 is crucial to effective tissue repair processes. Our data further suggest that AT-RvD1 may have potential as a novel therapeutic for organic dust exposure-induced, immune-mediated pulmonary and neurological inflammation, improving outcomes of those with these diseases.

The enigma of mitochondrial epigenetic alterations in air pollution-induced neurodegenerative diseases

The incidence of neurodegenerative diseases is a growing concern worldwide, affecting individuals from diverse backgrounds. Although these pathologies are primarily associated with aging and genetic susceptibility, their severity varies among the affected population. Numerous studies have indicated air pollution as a significant contributor to the increasing prevalence of neurodegeneration. Cohort studies have provided compelling evidence of the association between prolonged exposure to different air toxicants and cognitive decline, behavioural deficits, memory impairment, and overall neuronal health deterioration. Furthermore, molecular research has revealed that air pollutants can disrupt the body's protective mechanisms, participate in neuroinflammatory pathways, and cause neuronal epigenetic modifications. The mitochondrial epigenome is particularly interesting to the scientific community due to its potential to significantly impact our understanding of neurodegenerative diseases' pathogenesis and their release in the peripheral circulation. While protein hallmarks have been extensively studied, the possibility of using circulating epigenetic signatures, such as methylated DNA fragments, miRNAs, and genome-associated factors, as diagnostic tools and therapeutic targets requires further groundwork. The utilization of circulating epigenetic signatures holds promise for developing novel prognostic strategies, creating paramount point-of-care devices for disease diagnosis, identifying therapeutic targets, and developing clinical data-based disease models utilizing multi-omics technologies and artificial intelligence, ultimately mitigating the threat and prevalence of neurodegeneration.

Association Between Particulate Matter Pollutants and Ophthalmology Visits for Ocular Surface Irritation and Allergy

Background

The World Health Organization has declared climate change to be "the single biggest health threat facing humanity", yet there are limited studies on the impact of climate change-related air pollution on ocular health.

Objective

To explore associations between ocular surface irritation and allergy-related daily outpatient office visits with daily ambient particulate matter (PM) levels in the Denver Metropolitan Area.

Methods

Daily visit counts of ophthalmology outpatient offices were obtained from an academic health center (October 1st, 2015 to January 27th, 2023). Daily ambient average concentrations of PM ≤ 10 µm in diameter (PM10) and 2.5 micrometers or less in diameter (PM2.5) were obtained. Data were analyzed using distributed lag nonlinear models while accounting for the cumulative lagged effects of PM10 and PM2.5 for visits. Modifications due to temperature were assessed using stratified models.

Results

There were 144,313 ocular surface irritation and allergy visits to ophthalmic clinics during the study period. Daily visit counts increased with increasing daily ambient PM10 and PM2.5 concentrations. Five-day cumulative ambient PM10 concentrations at 80, 90, 100, and 110 µg/m3 showed higher rate ratios at each level from 1.77 (95% CI: 1.71, 1.84) at concentration of 80 to 2.20 (95% CI: 2.09, 2.30) for concentration of 110 µg/m3. Similarly, the visit rate ratios increased as the daily PM2.5 concentration increased, but this gradient effect was not significantly higher as the concentration increased. The effect of PM10 was higher on days when the temperature was below the average. Temperature did not affect the association between daily visit counts and PM2.5.

Conclusion

This study found that ambient PM increased the rate of ophthalmology visits due to ocular surface irritation and allergies. Most importantly, this association increased in magnitude with higher ambient PM concentrations. Additional studies are required to fully understand the effects of climate change-related stressors on ocular health.

Social cohesion as a modifier of joint air pollution exposure and incident dementia

Social cohesion can reduce stress, increase social interaction, and improve cognitive reserve. These social mechanisms may modify the effects of air pollution on dementia risk. This cohort study examines the potential moderating effect of social cohesion on associations between joint air pollution exposure and incident dementia leveraging data from 5112 community-dwelling adults ≥65 years of age enrolled in the National Health and Aging Trends Study (NHATS). Study participants were enrolled in 2011 and followed through 2018. We assigned 2010 residential census tract-level exposures to five air pollutants, particulate matter (PM) ≤ 10 μm in diameter, PM ≤ 2.5 μm in diameter, carbon monoxide, nitric oxide, and nitrogen dioxide, using the US Environmental Protection Agency's Community Multiscale Air Quality Modeling System. Dementia status was determined based on self- or proxy-reported dementia diagnosis or "probable dementia" according to NHATS cognitive screening tools. Participants' self-rated neighborhood social cohesion was evaluated based on three questions: neighbors knowing each other, being helpful, and being trustworthy. Social cohesion was dichotomized at the median into high vs low social cohesion. Associations between air pollutants and incident dementia were assessed using quantile g-computation Cox proportional hazard models and stratified by high vs low social cohesion, adjusting for age, sex, education, partner status, urbanicity, annual income, race and ethnicity, years lived at current residence, neighborhood disadvantage index, and tract segregation. High social cohesion (HR = 1.20, 95 % CI = 0.98, 1.47) and air pollution (HR = 1.08, 95 % CI = 0.92, 1.28) were not associated with incident dementia alone. However, when stratified, greater joint air pollution exposure increased dementia risk among participants at low (HR = 1.34, 95 % CI = 1.04, 1.72), but not high (HR = 1.00, 95 % CI = 0.93, 1.06) social cohesion. Air pollution was a risk factor for dementia only when reported social cohesion was low, suggesting that social interaction may play a protective role, mitigating dementia risk via air pollution exposure.

Prenatal Exposure to Source-Specific Fine Particulate Matter and Autism Spectrum Disorder

In this study, associations between prenatal exposure to fine particulate matter (PM2.5) from 9 sources and development of autism spectrum disorder (ASD) were assessed in a population-based retrospective pregnancy cohort in southern California. The cohort included 318,750 mother-child singleton pairs. ASD cases (N = 4559) were identified by ICD codes. Source-specific PM2.5 concentrations were estimated from a chemical transport model with a 4 × 4 km2 resolution and assigned to maternal pregnancy residential addresses. Cox proportional hazard models were used to estimate the hazard ratios (HR) of ASD development for each individual source. We also adjusted for total PM2.5 mass and in a separate model for all other sources simultaneously. Increased ASD risk was observed with on-road gasoline (HR [CI]: 1.18 [1.13, 1.24]), off-road gasoline (1.15 [1.12, 1.19]), off-road diesel (1.08 [1.05, 1.10]), food cooking (1.05 [1.02, 1.08]), aircraft (1.04 [1.01, 1.06]), and natural gas combustion (1.09 [1.06, 1.11]), each scaled to standard deviation increases in concentration. On-road gasoline and off-road gasoline were robust for other pollutant groups. PM2.5 emitted from different sources may have different impacts on ASD. The results also identify PM source mixtures for toxicological investigations that may provide evidence for future public health policies.

Particulate Matter-Induced Emerging Health Effects Associated with Oxidative Stress and Inflammation

Environmental pollution continues to increase with industrial development and has become a threat to human health. Atmospheric particulate matter (PM) was designated as a Group 1 carcinogen by the International Agency for Research on Cancer in 2013 and is an emerging global environmental risk factor that is a major cause of death related to cardiovascular and respiratory diseases. PM is a complex composed of highly reactive organic matter, chemicals, and metal components, which mainly cause excessive production of reactive oxygen species (ROS) that can lead to DNA and cell damage, endoplasmic reticulum stress, inflammatory responses, atherosclerosis, and airway remodeling, contributing to an increased susceptibility to and the exacerbation of various diseases and infections. PM has various effects on human health depending on the particle size, physical and chemical characteristics, source, and exposure period. PM smaller than 5 μm can penetrate and accumulate in the alveoli and circulatory system, causing harmful effects on the respiratory system, cardiovascular system, skin, and brain. In this review, we describe the relationship and mechanism of ROS-mediated cell damage, oxidative stress, and inflammatory responses caused by PM and the health effects on major organs, as well as comprehensively discuss the harmfulness of PM.

spconfShiny: An R Shiny application for calculating the spatial scale of smoothing splines for point data

Epidemiological analyses of environmental exposures often benefit from including spatial splines in models to account for confounding by spatial location. Understanding how the number of splines relates to physical spatial differences is not always intuitive and can be context-dependent. To address this, we developed a R Shiny application, spconfShiny, that provides a user-friendly platform to calculate an effective bandwidth metric that quantifies the relationship between spatial splines and the range of implied spatial smoothing. spconfShiny can be accessed at https://g2aging.shinyapps.io/spconfShiny/. We illustrate the procedure to compute the effective bandwidth and demonstrate its use for different numbers of spatial splines across England, India, Ireland, Northern Ireland, and the United States. Using spconfShiny, we show the effective bandwidth increases with the size of the region and decreases with the number of splines. Including 10 splines on a 10km grid corresponds to effective bandwidths of 92.2km in Ireland and 927.7km in the United States.

Associations between Fine Particulate Matter Components, Their Sources, and Cognitive Outcomes in Children Ages 9-10 Years Old from the United States

BACKGROUND

Emerging literature suggests that fine particulate matter [with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 )] air pollution and its components are linked to various neurodevelopmental outcomes. However, few studies have evaluated how PM 2.5 component mixtures from distinct sources relate to cognitive outcomes in children.

OBJECTIVES

This cross-sectional study investigated how ambient concentrations of PM 2.5 component mixtures relate to neurocognitive performance in 9- to 10-year-old children, as well as explored potential source-specific effects of these associations, across the US.

METHODS

Using spatiotemporal hybrid models, annual concentrations of 15 chemical components of PM 2.5 were estimated based on the residential address of child participants from the Adolescent Brain Cognitive Development (ABCD) Study. General cognitive ability, executive function, and learning/memory scores were derived from the NIH Toolbox. We applied positive matrix factorization to identify six major PM 2.5 sources based on the 15 components, which included crustal, ammonium sulfate, biomass burning, traffic, ammonium nitrate, and industrial/residual fuel burning. We then utilized weighted quantile sum (WQS) and linear regression models to investigate associations between PM 2.5 components' mixture, their potential sources, and children's cognitive scores.

RESULTS

Mixture modeling revealed associations between cumulative exposure and worse cognitive performance across all three outcome domains, including shared overlap in detrimental effects driven by ammonium nitrates, silicon, and calcium. Using the identified six sources of exposure, source-specific negative associations were identified between ammonium nitrates and learning & memory, traffic and executive function, and crustal and industrial mixtures and general cognitive ability. Unexpected positive associations were also seen between traffic and general ability as well as biomass burning and executive function.

DISCUSSION

This work suggests nuanced associations between outdoor PM 2.5 exposure and childhood cognitive performance, including important differences in cognition related both to individual chemicals as well as to specific sources of these exposures. https://doi.org/10.1289/EHP14418.

Association of midlife air pollution exposures and residential road proximity with incident dementia: The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

Increasing evidence links higher air pollution exposures to increased risk of cognitive impairment. While midlife risk factors are often most strongly linked to dementia risk, few studies have considered associations between midlife roadway proximity or ambient air pollution exposure and incident dementia decades later, in late life.

OBJECTIVES

Our objective was to determine if midlife exposures to ambient air pollution or roadway proximity are associated with increased risk of dementia in the Atherosclerosis Risk in Communities (ARIC) study over up to 29 years of follow-up.

METHODS

Our eligible sample included Black and White ARIC participants without dementia at Visit 2 (1990-1992). Participants were followed through Visit 7 (2018-2019), with dementia status and onset date defined based on formal dementia ascertainment at study visits, informant interviews, and surveillance efforts. We used adjusted Weibull survival models to assess the associations of midlife ambient air pollution and road proximity with incident dementia.

RESULTS

The median age at baseline (1990-1992, Visit 2) of the 12,700 eligible ARIC participants was 57.0 years; 56.0% were female, 24.2% were Black, and 78.9% had at least a high school education. Over up to 29 years of follow-up, 2511 (19.8%) persons developed dementia. No associations were found between ambient air pollutants and proximity to major roadways with risk of incident dementia. In exploratory analyses, living closer to roadways in midlife increased dementia risk in individuals younger at baseline and those without midlife hypertension, and there was evidence of increased risk of dementia with increased midlife exposure to NOx, several PM2.5 components, and trace metals among those with diabetes in midlife.

CONCLUSIONS

Midlife exposure to ambient air pollution and midlife roadway proximity was not associated with dementia risk over decades of follow-up. Further investigation to explore potential for greater susceptibility among specific subgroups identified here is needed.

Robust differential gene expression patterns in the prefrontal cortex of male mice exposed to an occupationally relevant dose of laboratory-generated wildfire smoke

Wildfires have become common global phenomena concurrent with warmer and drier climates and are now major contributors to ambient air pollution worldwide. Exposure to wildfire smoke has been classically associated with adverse cardiopulmonary health outcomes, especially in vulnerable populations. Recent work has expanded our understanding of wildfire smoke toxicology to include effects on the central nervous system and reproductive function; however, the neurotoxic profile of this toxicant remains ill-explored in an occupational context. Here, we sought to address this by using RNA sequencing to examine transcriptomic signatures in the prefrontal cortex of male mice modeling career wildland firefighter smoke exposure. We report robust changes in gene expression profiles between smoke-exposed samples and filtered air controls, evidenced by 2,862 differentially expressed genes (51.2% increased). We further characterized the functional relevance of these genes highlighting enriched pathways related to synaptic transmission, neuroplasticity, blood-brain barrier integrity, and neurotransmitter metabolism. Additionally, we identified possible contributors to these alterations through protein-protein interaction network mapping, which revealed a central node at ß-catenin and secondary hubs centered around mitochondrial oxidases, the Wnt signaling pathway, and gene expression machinery. The data reported here will serve as the foundation for future experiments aiming to characterize the phenotypic effects and mechanistic underpinnings of occupational wildfire smoke neurotoxicology.

Climate Change and Aging: Implications for Psychiatric Care

PURPOSE OF REVIEW

We reviewed recent evidence regarding the impact of climate change (specifically, high ambient temperatures, heatwaves, weather-related disasters, and air pollution) on older adults' mental health. We also summarized evidence regarding other medical problems that can occur in aging adults in connection with climate change, resulting in psychiatric manifestations or influencing psychopharmacological management.

RECENT FINDINGS

Older adults can experience anxiety, depressive, and/or posttraumatic stress symptoms, as well as sleep disturbances in the aftermath of climate disasters. Cognitive deficits may occur with exposure to air pollutants, heatwaves, or post-disaster. Individuals with major neurocognitive disorders and/or preexisting psychiatric illness have a higher risk of psychiatric hospitalizations after exposure to high temperatures and air pollution. There is a growing body of research regarding psychiatric clinical presentations associated with climate change in older adults. However, there is a paucity of evidence on management strategies. Future research should investigate culturally appropriate, cost-effective psychosocial and pharmacological interventions.

A Systematic Review of Air Pollution Exposure and Brain Structure and Function during Development

Objectives

Air pollutants are known neurotoxicants. In this updated systematic review, we evaluate new evidence since our 2019 systematic review on the effect of outdoor air pollution exposure on childhood and adolescent brain structure and function as measured by magnetic resonance imaging (MRI).

Methods

Using PubMed and Web of Science, we conducted an updated literature search and systematic review of articles published through March 2024, using key terms for air pollution and functional and/or structural MRI. Two raters independently screened all articles using Covidence and implemented the risk of bias instrument for systematic reviews informing the World Health Organization Global Air Quality Guidelines.

Results

We identified 222 relevant papers, and 14 new studies met our inclusion criteria. Including six studies from our 2019 review, the 20 publications to date include study populations from the United States, Netherlands, Spain, and United Kingdom. Studies investigated exposure periods spanning pregnancy through early adolescence, and estimated air pollutant exposure levels via personal monitoring, geospatial residential estimates, or school courtyard monitors. Brain MRI occurred when children were on average 6-14.7 years old; however, one study assessed newborns. Several MRI modalities were leveraged, including structural morphology, diffusion tensor imaging, restriction spectrum imaging, arterial spin labeling, magnetic resonance spectroscopy, as well as resting-state and task-based functional MRI. Air pollutants were associated with widespread brain differences, although the magnitude and direction of findings are largely inconsistent, making it difficult to draw strong conclusions.

Conclusion

Prenatal and childhood exposure to outdoor air pollution is associated with structural and functional brain variations. Compared to our initial 2019 review, publications doubled-an increase that testifies to the importance of this public health issue. Further research is needed to clarify the effects of developmental timing, along with the downstream implications of outdoor air pollution exposure on children's cognitive and mental health.

Criteria, Greenhouse Gas, and Hazardous Air Pollutant Emissions Factors from Residential Cordwood and Pellet Stoves Using an Integrated Duty Cycle Test Protocol

Air pollution from residential wood heating (RWH) presents challenges at the intersection of climate and public health. With a revised National Ambient Air Quality Standard (NAAQS, at 9 μg/m3) for particulate matter (PM) in the United States (U.S.), the Environmental Protection Agency (EPA) will likely classify new non-attainment areas due primarily to emissions from RWH. Agencies will use emissions factors (EFs) to develop attainment strategies. Many will rely on EPA modeling platforms based on data from the National Emissions Inventory (NEI). The NEI uses RWH EFs based on data from mid-1990's in-situ studies and a speciation profile from a 2001 study of fireplace emissions. The NEI does not include greenhouse gas (GHG) emissions for this sector, which plays a key role when assessing climate reduction strategies for the buildings sector. Here, we tested seven wood stoves to determine EFs, representing various vintages and control technologies, using a novel test method that reflects in-use operational settings called the Integrated Duty Cycle. The study measured multiple pollutants concurrently: criteria pollutants (particulate matter [PM], CO, and NOx), nonmethane total hydrocarbons (NMTHCs), GHGs, black carbon (eBC), brown carbon (BrC), and multiple hazardous air pollutants (HAPs). We found no significant difference in PM EFs between uncertified and non-catalytic stove technologies. RWH EF results from this study exceeded 2020 NEI RWH EFs for NMTHC and multiple HAPs. Applying our study's EFs to the 2020 NEI suggests that RWH, compared to all other sources, ranks as the 2nd largest source category of formaldehyde; the 3rd largest of benzene, 1,3-butadiene, and acrolein; and the 4th largest of Pb emissions. RWH also emits more methane compared to natural gas or oil residential heating, raising questions about substitution of wood as a climate neutral heating fuel. However, compared to uncertified stoves, pellet stove EFs (except toxic metals) were significantly lower (p < 0.01). In summary, RWH appears to be an underestimated source of PM (non-catalytic technology), methane, NMTHC, toxic metals, and other HAPs, which has important implications for climate and public health policy in the U.S. and globally.

Short-Term Exposure to Ambient Air Pollution and Antimicrobial Use for Acute Respiratory Symptoms

Importance

Ambient air pollution and antimicrobial resistance pose significant global public health challenges. It is not known whether ambient air pollution is associated with increased consumption of antimicrobials.

Objective

To assess whether a short-term association exists between ambient air pollution levels and antimicrobial consumption among the general population seeking primary care consultations for acute respiratory symptoms.

Design, Setting, and Participants

This 2-stage cross-sectional ecological time series analysis study using data on daily ambient air pollution and antimicrobial consumption was conducted in the 11 largest cities in Catalonia, Spain, from June 23, 2012, to December 31, 2019, among all inhabitants aged 12 years or older. Statistical analysis was performed from November 2022 to December 2023.

Exposures

Daily ambient air pollution (particulate matter of 10 μg/m3 [PM10], particulate matter of 2.5 μg/m3 [PM2.5], and nitrogen dioxide [NO2]).

Main Outcomes and Measures

The main outcome was antimicrobial consumption associated with primary care consultations for acute respiratory symptoms in the 30 days before and after the dispensing of the antimicrobial. Antimicrobial consumption was measured as defined daily doses (DDDs) per 1000 inhabitants per day.

Results

Among 1 938 333 inhabitants (median age, 48 years [IQR, 34-65 years]; 55% female participants), there were 8 421 404 antimicrobial dispensations, with a median of 12.26 DDDs per 1000 inhabitants per day (IQR, 6.03-15.32 DDDs per 1000 inhabitants per day). The median adjusted morbidity score was 2.0 (IQR, 1.0-5.0). For the 1 924 814 antimicrobial dispensations associated with primary care consultations for acute respiratory symptoms, there was a significant correlation between increases of 10 μg/m3 in the concentration of the 3 pollutants studied and heightened antimicrobial consumption at day 0 (PM10: relative risk [RR], 1.01 [95% CI, 1.01-1.02]; PM2.5: RR, 1.03 [95% CI, 1.01-1.04]; NO2: RR, 1.04 [95% CI, 1.03-1.05]). A delayed association emerged between increases in PM2.5 concentration and antimicrobial consumption between day 7 (RR, 1.00 [95% CI, 1.00-1.01]) and day 10 (RR, 1.00 [95% CI, 1.00-1.01]) after exposure.

Conclusions and Relevance

In this 2-stage cross-sectional study using ecological time series analysis, short-term exposure to air pollution was associated with increased antimicrobial use associated with primary care consultations for acute respiratory symptoms in the general population. This finding could contribute to informing policy decisions aimed at reducing air pollution and its associated risks, thereby promoting respiratory health and reducing antimicrobial use.

Single-domain magnetic particles with motion behavior under electromagnetic AC and DC fields are a fatal cargo in Metropolitan Mexico City pediatric and young adult early Alzheimer, Parkinson, frontotemporal lobar degeneration and amyotrophic lateral sclerosis and in ALS patients

Metropolitan Mexico City (MMC) children and young adults exhibit overlapping Alzheimer and Parkinsons' diseases (AD, PD) and TAR DNA-binding protein 43 pathology with magnetic ultrafine particulate matter (UFPM) and industrial nanoparticles (NPs). We studied magnetophoresis, electron microscopy and energy-dispersive X-ray spectrometry in 203 brain samples from 14 children, 27 adults, and 27 ALS cases/controls. Saturation isothermal remanent magnetization (SIRM), capturing magnetically unstable FeNPs ~ 20nm, was higher in caudate, thalamus, hippocampus, putamen, and motor regions with subcortical vs. cortical higher SIRM in MMC ≤ 40y. Motion behavior was associated with magnetic exposures 25-100 mT and children exhibited IRM saturated curves at 50-300 mT associated to change in NPs position and/or orientation in situ. Targeted magnetic profiles moving under AC/AD magnetic fields could distinguish ALS vs. controls. Motor neuron magnetic NPs accumulation potentially interferes with action potentials, ion channels, nuclear pores and enhances the membrane insertion process when coated with lipopolysaccharides. TEM and EDX showed 7-20 nm NP Fe, Ti, Co, Ni, V, Hg, W, Al, Zn, Ag, Si, S, Br, Ce, La, and Pr in abnormal neural and vascular organelles. Brain accumulation of magnetic unstable particles start in childhood and cytotoxic, hyperthermia, free radical formation, and NPs motion associated to 30-50 μT (DC magnetic fields) are critical given ubiquitous electric and magnetic fields exposures could induce motion behavior and neural damage. Magnetic UFPM/NPs are a fatal brain cargo in children's brains, and a preventable AD, PD, FTLD, ALS environmental threat. Billions of people are at risk. We are clearly poisoning ourselves.

Physicochemical Characterization of the Particulate Matter in New Jersey/New York City Area, Resulting from the Canadian Quebec Wildfires in June 2023

The global increase in wildfires, primarily driven by climate change, significantly affects air quality and health. Wildfire-emitted particulate matter (WFPM) is linked to adverse health effects, yet the toxicological mechanisms are not fully understood given its physicochemical complexity and the lack of spatiotemporal exposure data. This study focuses on the physicochemical characterization of WFPM from a Canadian wildfire in June 2023, which affected over 100 million people in the US Northeast, particularly around New Jersey/New York. Aerosol systems were deployed to characterize WFPM during the 3 day event, revealing unprecedented mass concentrations mainly in the WFPM0.1 and WFPM0.1-2.5 size fractions. Peak WFPM2.5 concentrations reached 317 μg/m3, nearly 10 times the National Ambient Air Quality Standard (NAAQS) 24 h average limit. Chemical analysis showed a high organic-to-total carbon ratio (96%), consistent with brown carbon wildfires nanoparticles. Large concentrations of high-molecular-weight PAHs were found predominantly bound to WFPM0.1, with retene, a molecular marker of biomass burning and a known teratogen, being the most abundant (>70%). Computational modeling estimated a total lung deposition of 9.15 mg over 72 h, highlighting the health risks of WFPM, particularly due to its long-distance travel capability and impact on densely populated areas.

Seasons of smoke and fire: preparing health systems for improved performance before, during, and after wildfires

Increased frequency, intensity, and duration of wildfires are intensifying exposure to direct and smoke-related hazards in many areas, leading to evacuation and smoke-related effects on health and health systems that can affect regions extending over thousands of kilometres. Effective preparation and response are currently hampered by inadequate training, continued siloing of disciplines, insufficient finance, and inadequate coordination between health systems and governance at municipal, regional, national, and international levels. This Review highlights the key health and health systems considerations before, during, and after wildfires, and outlines how a health system should respond to optimise population health outcomes now and into the future. The focus is on the implications of wildfires for air quality, mental health, and emergency management, with elements of international policy and finance also addressed. We discuss commonalities of existing climate-resilient health care and disaster management frameworks and integrate them into an approach that addresses issues of financing, leadership and governance, health workforce, health information systems, infrastructure, supply chain, technologies, community interaction and health-care delivery, before, during, and after a wildfire season. This Review is a practical briefing for leaders and health professionals facing severe wildfire seasons and a call to break down silos and join with other disciplines to proactively plan for and fund innovation and coordination in service of a healthier future.

Toward cleaner air and better health: Current state, challenges, and priorities

The most up-to-date estimate of the global burden of disease indicates that ambient air pollution, including fine particulate matter and ozone, contributes to an estimated 5.2 million deaths each year. In this review, we highlight the challenges in estimating population exposure to air pollution and attributable health risks, particularly in low- and middle-income countries and among vulnerable populations. To protect public health, the evidence so far confirms urgent needs to prioritize interdisciplinary research on air pollution exposure and risk assessment and to develop evidence-based intervention policies and risk communication strategies. Here, we synthesize the emerging evidence supporting the monitoring and evaluation of the progress in implementation of the Global Air Quality Guidelines prepared by the World Health Organization.

Charting Alzheimer's Disease and Dementia: Epidemiological Insights, Risk Factors and Prevention Pathways

Alzheimer's disease (AD), the most common cause of dementia, is a complex and multifactorial condition without cure at present. The latest treatments, based on anti-amyloid monoclonal antibodies, have only a modest effect in reducing the progression of cognitive decline in AD, whereas the possibility of preventing AD has become a crucial area of research. In fact, recent studies have observed a decrease in dementia incidence in developed regions such as the US and Europe. However, these trends have not been mirrored in non-Western countries (Japan or China), and the contributing factors of this reduction remain unclear. The Lancet Commission has delineated a constrained classification of 12 risk factors across different life stages. Nevertheless, the scientific literature has pointed to over 200 factors-including sociodemographic, medical, psychological, and sociocultural conditions-related to the development of dementia/AD. This narrative review aims to synthesize the risk/protective factors of dementia/AD. Essentially, we found that risk/protective factors vary between individuals and populations, complicating the creation of a unified prevention strategy. Moreover, dementia/AD explanatory mechanisms involve a diverse array of genetic and environmental factors that interact from the early stages of life. In the future, studies across different population-based cohorts are essential to validate risk/protective factors of dementia. This evidence would help develop public health policies to decrease the incidence of dementia.

Bioaerosol Exposures and Respiratory Diseases in Cannabis Workers

PURPOSE OF REVIEW

This review investigates occupational inhalation hazards associated with biologically derived airborne particles (bioaerosols) generated in indoor cannabis cultivation and manufacturing facilities.

RECENT FINDINGS

Indoor cannabis production is growing across the US as are recent reports of respiratory diseases among cannabis workers, including occupational asthma morbidity and mortality. More information is needed to understand how bioaerosol exposure in cannabis facilities impacts worker health and occupational disease risk. Preliminary studies demonstrate a significant fraction of airborne particles in cannabis facilities are comprised of fungal spores, bacteria, and plant material, which may also contain hazardous microbial metabolites and allergens. These bioaerosols may pose pathogenic, allergenic, toxigenic, and pro-inflammatory risks to workers. The absence of multi-level, holistic bioaerosol research in cannabis work environments necessitates further characterization of the potential respiratory hazards and effective risk prevention methods to safeguard occupational health as the cannabis industry continues to expand across the US and beyond.

Rural-Urban mild cognitive impairment comparison in West Michigan through EHR

INTRODUCTION

Mild cognitive impairment (MCI) is a significant public health concern and a potential precursor to Alzheimer's disease (AD). This study leverages electronic health record (EHR) data to explore rural-urban differences in MCI incidence, risk factors, and healthcare navigation in West Michigan.

METHODS

Analysis was conducted on 1,528,464 patients from Corewell Health West, using face-to-face encounters between 1/1/2015 and 7/31/2022. MCI cases were identified using International Classification of Diseases (ICD) codes, focusing on patients aged 45+ without prior MCI, dementia, or AD diagnoses. Incidence rates, cumulative incidences, primary care physicians (PCPs), and neuropsychology referral outcomes were examined across rural and urban areas. Risk factors were evaluated through univariate and multivariate Cox regression analyses. The geographic distribution of patient counts, hospital locations, and neurology department referrals were examined.

RESULTS

Among 423,592 patients, a higher MCI incidence rate was observed in urban settings compared to rural settings (3.83 vs. 3.22 per 1,000 person-years). However, sensitivity analysis revealed higher incidence rates in rural areas when including patients who progressed directly to dementia. Urban patients demonstrated higher rates of referrals to and completion of neurological services. While the risk factors for MCI were largely similar across urban and rural populations, urban-specific factors for incident MCI are hearing loss, inflammatory bowel disease, obstructive sleep apnea, insomnia, being African American, and being underweight. Common risk factors include diabetes, intracranial injury, cerebrovascular disease, coronary artery disease, stroke, Parkinson's disease, epilepsy, chronic obstructive pulmonary disease, depression, and increased age. Lower risk was associated with being female, having a higher body mass index, and having a higher diastolic blood pressure.

DISCUSSION

This study highlights rural-urban differences in MCI incidence and access to care, suggesting potential underdiagnosis in rural areas likely due to reduced access to specialists. Future research should explore socioeconomic, environmental, and lifestyle determinants of MCI to refine prevention and management strategies across geographic settings.

Highlights

Leveraged EHRs to explore rural-urban differences in MCI in West Michigan.Revealed a significant underdiagnosis of MCI, especially in rural areas.Observed lower rates of neurological referrals and completions for rural patients.Identified risk factors specific to rural and urban populations.

Risk of dementia due to Co-exposure to air pollution and neighborhood disadvantage

BACKGROUND

Co-exposure to air pollution and neighborhood disadvantage may influence cognition decline. We tested these associations in the context of dementia risk.

METHODS

We leveraged a cohort of adults ≥65 years (n = 5397) enrolled from 2011 to 2018 in the National Health and Aging Trends Study (NHATS). Particulate matter (PM) ≤ 10 μm in diameter, PM ≤ 2.5 μm in diameter, carbon monoxide, nitric oxide, and nitrogen dioxide - and neighborhood disadvantage were tested for joint associations with dementia risk. Pollutant concentrations at the 2010 census tract level were assigned using the US Environmental Protection Agency's Community Multiscale Air Quality Modeling System. Neighborhood disadvantage was defined using the tract Social Deprivation Index (SDI). Dementia was determined through self- or proxy-report or scores indicative of "probable dementia" according to NHATS screening tools. Joint effects of air pollutants and SDI were tested using quantile g-computation Cox proportional hazards models. We also stratified joint air pollution effects across SDI tertiles. Analyses adjusted for age at enrollment, sex, education, partner status, urbanicity, income, race and ethnicity, years at residence, census segregation, and census region.

RESULTS

SDI score (aHR = 1.08; 95% CI 0.96, 1.22), joint air pollution (aHR = 1.03, 95% CI 0.92, 1.16) and joint SDI with air pollution (aHR = 1.04, 95% CI 0.89, 1.22) were not associated with dementia risk. After accounting for competing risk of death, joint SDI with air pollution was not associated with dementia risk (aHR = 1.06; 95% CI 0.87, 1.29). In stratified models, joint air pollution was associated with greater risk of dementia at high (aHR = 1.19; 95% CI 0.87, 1.63), but not at medium or low SDI.

CONCLUSION

Air pollution was associated with greater dementia risk in disadvantaged areas after accounting for competing risks. Air pollution associations with dementia incidence may be attenuated when other risk factors are more prominent in disadvantaged neighborhoods.

Source-Specific Air Pollution and Loss of Independence in Older Adults Across the US

Importance

Air pollution is a recognized risk factor associated with chronic diseases, including respiratory and cardiovascular conditions, which can lead to physical and cognitive impairments in later life. Although these losses of function, individually or in combination, reduce individuals' likelihood of living independently, little is known about the association of air pollution with this critical outcome.

Objective

To investigate associations between air pollution and loss of independence in later life.

Design, Setting, and Participants

This cohort study was conducted as part of the Environmental Predictors Of Cognitive Health and Aging study and used 1998 to 2016 data from the Health and Retirement Study. Participants included respondents from this nationally representative, population-based cohort who were older than 50 years and had not previously reported a loss of independence. Analyses were performed from August 31 to October 15, 2023.

Exposures

Mean 10-year pollutant concentrations (particulate matter less than 2.5 μm in diameter [PM2.5] or ranging from 2.5 μm to 10 μm in diameter [PM10-2.5], nitrogen dioxide [NO2], and ozone [O3]) were estimated at respondent addresses using spatiotemporal models along with PM2.5 levels from 9 emission sources.

Main Outcomes and Measures

Loss of independence was defined as newly receiving care for at least 1 activity of daily living or instrumental activity of daily living due to health and memory problems or moving to a nursing home. Associations were estimated with generalized estimating equation regression adjusting for potential confounders.

Results

Among 25 314 respondents older than 50 years (mean [SD] baseline age, 61.1 [9.4] years; 11 208 male [44.3%]), 9985 individuals (39.4%) experienced lost independence during a mean (SD) follow-up of 10.2 (5.5) years. Higher exposure levels of mean concentration were associated with increased risks of lost independence for total PM2.5 levels (risk ratio [RR] per 1-IQR of 10-year mean, 1.05; 95% CI, 1.01-1.10), PM2.5 levels from road traffic (RR per 1-IQR of 10-year mean, 1.09; 95% CI, 1.03-1.16) and nonroad traffic (RR per 1-IQR of 10-year mean, 1.13; 95% CI, 1.03-1.24), and NO2 levels (RR per 1-IQR of 10-year mean, 1.05; 95% CI, 1.01-1.08). Compared with other sources, traffic-generated pollutants were most consistently and robustly associated with loss of independence; only road traffic-related PM2.5 levels remained associated with increased risk after adjustment for PM2.5 from other sources (RR per 1-IQR increase in 10-year mean concentration, 1.10; 95% CI, 1.00-1.21). Other pollutant-outcome associations were null, except for O3 levels, which were associated with lower risks of lost independence (RR per 1-IQR increase in 10-year mean concentration, 0.94; 95% CI, 0.92-0.97).

Conclusions and Relevance

This study found that long-term exposure to air pollution was associated with the need for help for lost independence in later life, with especially large and consistent increases in risk for pollution generated by traffic-related sources. These findings suggest that controlling air pollution could be associated with diversion or delay of the need for care and prolonged ability to live independently.

Wildfire Smoke and Its Neurological Impact

This Viewpoint calls for a more concerted research effort aimed at establishing a robust link between wildfire smoke exposure and neurological effects.

A review of common statistical methods for dealing with multiple pollutant mixtures and multiple exposures

Traditional environmental epidemiology has consistently focused on studying the impact of single exposures on specific health outcomes, considering concurrent exposures as variables to be controlled. However, with the continuous changes in environment, humans are increasingly facing more complex exposures to multi-pollutant mixtures. In this context, accurately assessing the impact of multi-pollutant mixtures on health has become a central concern in current environmental research. Simultaneously, the continuous development and optimization of statistical methods offer robust support for handling large datasets, strengthening the capability to conduct in-depth research on the effects of multiple exposures on health. In order to examine complicated exposure mixtures, we introduce commonly used statistical methods and their developments, such as weighted quantile sum, bayesian kernel machine regression, toxic equivalency analysis, and others. Delineating their applications, advantages, weaknesses, and interpretability of results. It also provides guidance for researchers involved in studying multi-pollutant mixtures, aiding them in selecting appropriate statistical methods and utilizing R software for more accurate and comprehensive assessments of the impact of multi-pollutant mixtures on human health.

2024 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including prevalence and incidence, mortality and morbidity, use and costs of care and the ramifications of AD for family caregivers, the dementia workforce and society. The Special Report discusses the larger health care system for older adults with cognitive issues, focusing on the role of caregivers and non-physician health care professionals. An estimated 6.9 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060, barring the development of medical breakthroughs to prevent or cure AD. Official AD death certificates recorded 119,399 deaths from AD in 2021. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death in the United States. Official counts for more recent years are still being compiled. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2021, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 140%. More than 11 million family members and other unpaid caregivers provided an estimated 18.4 billion hours of care to people with Alzheimer's or other dementias in 2023. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $346.6 billion in 2023. Its costs, however, extend to unpaid caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Members of the paid health care and broader community-based workforce are involved in diagnosing, treating and caring for people with dementia. However, the United States faces growing shortages across different segments of the dementia care workforce due to a combination of factors, including the absolute increase in the number of people living with dementia. Therefore, targeted programs and care delivery models will be needed to attract, better train and effectively deploy health care and community-based workers to provide dementia care. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2024 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $360 billion. The Special Report investigates how caregivers of older adults with cognitive issues interact with the health care system and examines the role non-physician health care professionals play in facilitating clinical care and access to community-based services and supports. It includes surveys of caregivers and health care workers, focusing on their experiences, challenges, awareness and perceptions of dementia care navigation.

Assessing pesticides in the atmosphere: A global study on pollution, human health effects, monitoring network and regulatory performance

Pesticides are widely used in agriculture, but their impact on the environment and human health is a major concern. While much attention has been given to their presence in soil, water, and food, there have been few studies on airborne pesticide pollution on a global scale. This study aimed to assess the extent of atmospheric pesticide pollution in countries worldwide and identify regional differences using a scoring approach. In addition to analyzing the health risks associated with pesticide pollution, we also examined agricultural practices and current air quality standards for pesticides in these countries. The pollution scores varied significantly among the countries, particularly in Europe. Asian and Oceanic countries generally had higher scores compared to those in the Americas, suggesting a relatively higher level of air pollution caused by pesticides in these regions. It is worth noting that the current pollution levels, as assessed theoretically, pose minimal health risks to humans. However, studies in the literature have shown that excessive exposure to pesticides present in the atmosphere has been associated with various health problems, such as cancer, neuropsychiatric disorders, and other chronic diseases. Interestingly, European countries had the highest overall pesticide application intensities, but this did not necessarily correspond to higher atmospheric pesticide pollution scores. Only a few countries have established air quality standards specifically for pesticides. Furthermore, pollution scores across states in the USA were investigated and the global sampling sites were mapped. The findings revealed that the scores varied widely in the USA and the current sampling sites were limited or unevenly distributed in some countries, particularly the Nordic countries. These findings can help global relevant environmental agencies to set up comprehensive monitoring networks. Overall, the present research highlights the need to create a pesticide monitoring system and increase efforts to enhance pesticide regulation, ensure consistency in standards, and promote international cooperation.

The firestorm within: A narrative review of extreme heat and wildfire smoke effects on brain health

Climate change is generating increased heatwaves and wildfires across much of the world. With these escalating environmental changes comes greater impacts on human health leading to increased numbers of people suffering from heat- and wildfire smoke-associated respiratory and cardiovascular impairment. One area of health impact of climate change that has received far less attention is the effects of extreme heat and wildfire smoke exposure on human brain health. As elevated temperatures, and wildfire-associated smoke, are increasingly experienced simultaneously over summer periods, understanding this combined impact is critical to management of human health especially in the elderly, and people with dementia, and other neurological disorders. Both extreme heat and wildfire smoke air pollution (especially particulate matter, PM) induce neuroinflammatory and cerebrovascular effects, oxidative stress, and cognitive impairment, however the combined effect of these impacts are not well understood. In this narrative review, a comprehensive examination of extreme heat and wildfire smoke impact on human brain health is presented, with a focus on how these factors contribute to cognitive impairment, and dementia, one of the leading health issues today. Also discussed is the potential impact of combined heat and wildfire smoke on brain health, and where future efforts should be applied to help advance knowledge in this rapidly growing and critical field of health research.

Occupational and domestic exposure associations with cerebral small vessel disease and vascular dementia: A systematic review and meta-analysis

INTRODUCTION

The prevalence of cerebral smallvessel disease (SVD) and vascular dementia according to workplace or domestic exposure to hazardous substances is unclear.

METHODS

We included studies assessing occupational and domestic hazards/at-risk occupations and SVD features. We pooled prevalence estimates using random-effects models where possible, or presented a narrative synthesis.

RESULTS

We included 85 studies (n = 47,743, mean age = 44·5 years). 52/85 reported poolable estimates. SVD prevalence in populations exposed to carbon monoxide was 81%(95% CI = 60-93%; n = 1373; results unchanged in meta-regression), carbon disulfide73% (95% CI = 54-87%; n = 131), 1,2-dichloroethane 88% (95% CI = 4-100%, n = 40), toluene 82% (95% CI = 3-100%, n = 64), high altitude 49% (95% CI = 38-60%; n = 164),and diving 24% (95% CI = 5-67%, n = 172). We narratively reviewed vascular dementia studies and contact sport, lead, military, pesticide, and solvent exposures as estimates were too few/varied to pool.

DISCUSSION

SVD and vascular dementia may be associated with occupational/domestic exposure to hazardous substances. CRD42021297800.

The Burden of Air Pollution on Skin Health: a Brief Report and Call to Action

INTRODUCTION

Air pollution in North America has intensified due to wildfires in recent years. In 2023, the wildfires in the Canadian province of Quebec caused a southward spread of pollutants, negatively affecting air quality and thereby aggravating certain health conditions in northeastern USA. This study examines the impact of air pollution on atopic dermatitis (AD) and skin health and how wildfires can exacerbate the burden of disease.

METHODS

Carbon monoxide levels measured by the U.S. Environmental Protection Agency (EPA) in the Boston region during the months following the Canadian wildfires of 2023 were collected from the U.S. EPA Outdoor Air Quality webpage. Patient records on dermatology clinic visits for dermatitis and eczema at the Mass General Brigham (MGB) hospital system, 300 miles from the wildfires, were examined, and the data compared with data from the corresponding months in 2019-2022 for historical control. No individual patient data were collected.

RESULTS

A notable rise and atypical summer peak in carbon monoxide (CO) levels in the Boston region during 2023 correlated with a spike in AD, dermatitis, and eczema-related dermatology clinic visits within the MGB hospital system, as compared with the prior 4 years.

CONCLUSION

The synchronized atypical peaks of CO levels and AD-related visits during the summer of 2023 highlight the potential impact of acute air pollution events such as wildfires on air quality and the consequences for skin health. Air pollution, exacerbated by wildfires, can damage the skin through the smoke and chemicals utilized for extinguishing fires, which contain multiple potential allergens and irritants to the skin, such as CO, particulate matter (PM2.5), and ammonium phosphates, triggering airway and skin inflammation and flares of AD. This issue disproportionately affects vulnerable populations, including low-income communities and the geriatric and pediatric populations. Healthcare professionals and government agencies must work together to improve air quality and purification policies and initiatives to lower the burden of skin disease, especially for vulnerable communities.

Can Incorrect Analysis of Time-Dependent Exposure Explain Associations between PM2.5 Exposure and Risk of Dementia?

Background

Epidemiological studies have reported positive associations between long-term exposure to particulate matter of 2.5 microns or less in diameter (PM2.5) and risk of Alzheimer's disease and other clinical dementia. Many of these studies have analyzed data using Cox Proportional Hazards (PH) regression, which estimates a hazard ratio (HR) for the treatment (in this case, exposure) effect on the time-to-event outcome while adjusting for influential covariates. PM2.5 levels vary over time. As air quality standards for PM2.5 have become more stringent over time, average outdoor PM2.5 levels have decreased substantially.

Objective

Investigate whether a Cox PH analysis that does not properly account for exposure that varies over time could produce a biased HR of similar magnitude to the HRs reported in recent epidemiological studies of PM2.5 and dementia risk.

Methods

Simulation analysis.

Results

We found that the biased HR can affect statistical analyses that consider exposure levels at event times only, especially if PM2.5 levels decreased consistently over time. Furthermore, the direction of such bias is away from the null and of a magnitude that is consistent with the reported estimates of dementia risk in several epidemiological studies of PM2.5 exposure (HR≈1.2 to 2.0).

Conclusions

This bias can be avoided by correctly assigning exposure to study subjects throughout the entire follow-up period. We recommend that investigators provide a detailed description of how time-dependent exposure variables were accounted for in their Cox PH analyses when they report their results.

Prevalence of Dementia and Cognitive Impairment in East Africa Region: A Scoping Review of Population-Based Studies and Call for Further Research

Background

Population-based research on the prevalence and determinants of dementia, Alzheimer's disease, and cognitive impairment is scarce in East Africa.

Objective

To provide an overview of community- and population-based studies among older adults on the prevalence of dementia and cognitive impairment in East Africa, and identify research gaps.

Methods

We carried out a literature search using three electronic databases (PubMed, Scopus, Google Scholar) using pertinent search terms.

Results

After screening 445 publications, we identified four publications on the population-based prevalence of dementia, and three on cognitive impairment. Prevalence rates varied from 6- 23% for dementia, and 7- 44% for cognitive impairment, among participants aged≥50-70 years. Old age and a lower education level were risk factors for dementia and cognitive impairment. Physical inactivity, lack of a ventilated kitchen, and history of central nervous system infections and chronic headache were associated with increased odds of dementia. Female sex, depression, having no spouse, increased lifetime alcohol consumption, low income, rural residence, and low family support were associated with increased odds of cognitive impairment. Potential misclassification and non-standardized data collection methods are research gaps that should be addressed in future studies.

Conclusions

Establishing collaborative networks and partnering with international research institutions may enhance the capacity for conducting population-based studies on dementia and cognitive impairment in East Africa. Longitudinal studies may provide valuable insights on incidence, as well as potential risk and protective factors of dementia and cognitive impairment, and may inform the development of targeted interventions including preventive strategies in the region.