Short-term exposure to ultrafine particles and mortality and hospital admissions due to respiratory and cardiovascular diseases in Copenhagen, Denmark

Short-term exposure to ultrafine particles and asthma hospital admissions in children in Copenhagen, Denmark

BACKGROUND

Ultrafine particles (UFP; <0.1 µm in diameter) are not regulated or commonly monitored but may be harmful to human health, particularly for children. In this study, we aimed to examine the association between short-term exposure to UFP and asthma hospital admissions in children.

METHODS

Daily UFP concentrations (2002-2018) were monitored at an urban background station in Copenhagen, Denmark. Asthma hospital admissions, demographic and socioeconomic information of children (0-18 years) were obtained from registries. A case-crossover design was applied to estimate the association between hospital admissions and up to 6-day UFP exposure windows for all children, and stratified by age, sex, family income, mother's education, prior asthma or prior respiratory infection.

RESULTS

We observed 15 903 asthma hospital admissions in total. An IQR increase in UFP was significantly associated with asthma hospital admissions, strongest at 2-day exposure windows (risk ratio (RR): 1.17 (95% CI: 1.09, 1.25)). These associations remained unchanged when adjusting for particulate matter <2.5 µm in diameter (PM2.5) or nitrogen dioxide (NO2), for which we also detected significant positive associations. Associations with UFP were stronger for school-aged children (5-14 years: RR: 1.26 (95% CI: 1.15, 1.38)) than for children younger than 5 years (1.01 (95% CI: 0.93, 1.10)).

CONCLUSIONS

In this large study in a low-exposure setting, we find that short-term exposure to UFP can trigger asthma hospital admissions in children, independently of associations with PM2.5 or NO2. This study adds evidence calling for the regulation and improvement of UFP exposure assessment to protect children's health in urban areas.

Differential inflammation, oxidative stress and cardiovascular damage markers of nano- and micro-particle exposure in mice: Implications for human disease burden

Particulate matter (PM) poses a significant risk to human health; however, it remains uncertain which size fraction is especially harmful and what mechanisms are involved. We investigated the varying effects of particle size on specific organ systems using a custom mouse exposure system and synthetic PM (SPM). Whole-body exposure of mice showed that micrometer-sized fine SPM (2-4 μm) accumulated in the lungs, the primary entry organ, while nanometer-sized SPM (<250 nm) did not accumulate, suggesting a transition into circulation. Mice exposed to micro-SPM exhibited inflammation and NADPH oxidase-derived oxidative stress in the lungs. In contrast, nano-SPM-exposed mice did not display oxidative stress in the lungs but rather at the brain, heart, and vascular levels, supporting the hypothesis that they penetrate the lungs and reach the circulation. Sources of reactive oxygen species from micro-SPM in the lung are NOX1 and NOX2, driven by pulmonary inflammation, while oxidative stress from nano-SPM in the heart is mediated by protein kinase C-dependent p47phox phosphorylation, leading to NOX2 activation in infiltrated monocytes. Endothelial dysfunction and increased blood pressure were more pronounced in nano-SPM-exposed mice, also supported by elevated endothelin-1 and reduced endothelial nitric oxide synthase expression, which enhances constriction and diminishes vasodilation. Further, we estimated the cardiovascular disease burden of nano-particles in humans based on global exposure data and hazard ratios from an epidemiological cohort study. These results provide novel insights into the disease burdens of inhaled nano- and micro-particles (corresponding to fine and ultrafine categories), guiding future studies.

Individual effects and interactions between ultrafine particles and extreme temperatures on hospital admissions of high burden diseases

BACKGROUND

Health effects of ultrafine particles (UFPs) and their interactions with temperature are less studied. We investigated the risks of UFPs concentrations and extreme temperatures on hospitalizations for high-burden diseases (HBDs) in New York State (NYS).

METHODS

This case-crossover study included hospitalizations for HBDs that contain ischemic heart diseases, diabetes, stroke, kidney diseases, and depression using NYS Hospital Discharge Data (2013-2018). Daily pollutants and temperature data were obtained from a chemical transport model validated by multiple prior studies. UFP changes were measured using interquartile range increase, and extreme heat and cold were defined as temperatures >= 90th% and <=10th% respectively by month and location. Conditional logistic regression was applied controlling for criteria pollutants, relative humidity, and time-varying variables.

RESULTS

Among 1,308,518 cases, significant risk ratios (RR) were observed for UFPs (RRs ranged: 1.009-1.012) and extreme heat (RRs ranged: 1.024-1.028) on overall HBDs, but extreme cold had protective effects on HBDs. The adverse effect of UFPs had significant interactions with extreme cold and was higher in winter and fall. UFPs affected all HBD subtypes except kidney diseases, and extreme heat increased the risks of ischemic heart disease and kidney disease. There were disparities across demographics in exposures-HBDs associations although they were not statistically significant. Elevated UFP concentrations were associated with four clinical indicators (hospital stays, charges etc.).

CONCLUSION

We observe positive associations between elevated UFP concentrations or extreme heat and HBD hospitalizations, but negative associations with extreme cold. The UFPs' risks were higher in children and during cold seasons.

Spatial and temporal variation of façade-level particle number concentrations using portable monitors in Copenhagen, Denmark

Ultrafine particles (UFP), commonly expressed as particle number concentrations (PNC), have been associated with harm to human health yet are currently not regulated or routinely monitored in many places. This has limited the potential for studies of health effects of long-term exposure to UFP. The present study aims to understand the spatial and temporal variation in façade-level UFP exposures in Copenhagen, Denmark. We measured PNC at the façades of 27 residences across the city for approximately 72 h each in two campaigns and continuously at an urban background reference site for twelve consecutive months, using portable monitors (miniature diffusion size classifiers [DiSCminis]). We estimated annual means at the residential sites based on temporal adjustment using reference site data. Furthermore, we co-located the DiSCminis at a regulatory monitoring station on three occasions and compared daily means from our reference site to those from seven fixed-site monitoring stations throughout the city. Annual mean PNC at the reference site was 4715 (SD of hourly mean: 3001) pt/cm3, while annual means at 27 residences were slightly higher with a mean of 5201 pt/cm3 (SD: 807), ranging between 3735 and 6588 pt/cm3. The two individual adjusted campaign-specific means at 27 residential sites were weakly correlated (Spearman's correlation 0.11) and had an intra-class correlation coefficient of 0.06 (95%-confidence interval: -0.18, 0.28). Daily PNC at the reference site was highly correlated (R = 0.64-0.84) with PNC monitored at seven fixed-site stations throughout the city. We observed a seasonal trend at the reference site with the highest PNC in spring. Our measurement campaign revealed that façade-level PNC at residences in Copenhagen in 2021-2022 was relatively low with small spatial variability. The large variability in time suggests possibly longer and more frequent measurement campaigns to obtain more stable annual averages. Our study illustrates the challenges of UFP long-term exposure assessment.

Air pollution control and health economic burdens: Evidence from a megacity in China from 2014 through 2022

The Guangdong-Hong Kong-Macao Greater Bay Area (GBA) stands as China's foremost region in air pollution control. Shenzhen, as a model city, was selected to quantify the health-economic gains brought about by pollution control efforts. The paper showcased the exemplary practices of GBA in safeguarding the blue sky, providing a template for other regions. We assessed the variation of health impacts and economic burdens in Shenzhen from 2014 to 2022 using the proportional hazards model based on Poisson regression, along with the value of a statistical life, the cost of illness, and the willingness-to-pay approach. The results showed that only the premature mortality and economic burdens attributable to PM2.5 exhibited improvement prior to the COVID-19, with a total reduction of 9846.65 (95%Cl: 9846.65-9846.65) premature deaths and a cost saving of 63.93 (95%Cl: 63.93-63.93) million dollars. Short-term public health policies may affect the outcomes of air quality management, most types of health impacts and economic burdens showed a cliff decline during the pandemic. In addition, the study revealed that cardiovascular health economic burdens outweighed respiratory ones at the premature mortality level, while the opposite scenario was observed at the hospitalization level. This paper advocated for the strengthening of pollution control efforts, especially focusing on industrial emission reduction and intelligent transportation. The theoretical study of O3 and the synergistic management of O3 and PM2.5 should be advanced. Additionally, health education should be emphasized, and residents should be encouraged to cultivate personal hygiene habits.

On the dose-response association of fine and ultrafine particles in an urban atmosphere: toxicological outcomes on bronchial cells at realistic doses of exposure at the Air Liquid Interface

Air pollution and particulate matter (PM) are the leading environmental cause of death worldwide. Exposure limits have lowered to increase the protection of human health; accordingly, it becomes increasingly important to understand the toxicological mechanisms on cellular models at low airborne PM concentrations which are relevant for actual human exposure. The use of air liquid interface (ALI) models, which mimic the interaction between airborne pollutants and lung epithelia, is also gaining importance in inhalation toxicological studies. This study reports the effects of ALI direct exposure of bronchial epithelial cells BEAS-2B to ambient PM1 (i.e. particles with aerodynamic diameter lower than 1 μm). Gene expression (HMOX, Cxcl-8, ATM, Gadd45-a and NQO1), interleukin (IL)-8 release, and DNA damage (Comet assay) were evaluated after 24 h of exposure. We report the dose-response curves of the selected toxicological outcomes, together with the concentration-response association and we show that the two curves differ for specific responses highlighting that concentration-response association may be not relevant for understanding toxicological outcomes. Noteworthy, we show that pro-oxidant effects may be driven by the deposition of freshly emitted particles, regardless of the airborne PM1 mass concentration. Furthermore, we show that reference airborne PM1 metrics, namely airborne mass concentration, may not always reflect the toxicological process triggered by the aerosol. These findings underscore the importance of considering different aerosol metrics to assess the toxicological potency of fine and ultrafine particles. To better protect human health additional metrics should be defined, than account for the properties of the entire aerosol mixture including specific as particle size (i.e. particles with aerodynamic diameter lower than 20 nm), the relevant aerosol sources (e.g., traffic combustion, secondary organic aerosol …) as well as their atmospheric processing (freshly emitted vs aged ones).

Predicting within-city spatiotemporal variations in daily median outdoor ultrafine particle number concentrations and size in Montreal and Toronto, Canada

Background

Epidemiological evidence suggests that long-term exposure to outdoor ultrafine particles (UFPs, <0.1 μm) may have important human health impacts. However, less is known about the acute health impacts of these pollutants as few models are available to estimate daily within-city spatiotemporal variations in outdoor UFPs.

Methods

Several machine learning approaches (i.e., generalized additive models, random forest models, and extreme gradient boosting) were used to predict daily spatiotemporal variations in outdoor UFPs (number concentration and size) across Montreal and Toronto, Canada using a large database of mobile monitoring measurements. Separate models were developed for each city and all models were evaluated using a 10-fold cross-validation procedure.

Results

In total, our models were based on measurements from 12,705 road segments in Montreal and 10,929 road segments in Toronto. Daily median outdoor UFP number concentrations varied substantially across both cities with 1st-99th percentiles ranging from 1389 to 181,672 in Montreal and 2472 to 118,544 in Toronto. Outdoor UFP size tended to be smaller in Montreal (mean [SD]: 34 nm [15]) than in Toronto (mean [SD]: 44 nm [25]). Extreme gradient boosting models performed best and explained the majority of spatiotemporal variations in outdoor UFP number concentrations (Montreal, R 2: 0.727; Toronto, R 2: 0.723) and UFP size (Montreal, R 2: 0.823; Toronto, R 2: 0.898) with slopes close to one and intercepts close to zero for relationships between measured and predicted values.

Conclusion

These new models will be applied in future epidemiological studies examining the acute health impacts of outdoor UFPs in Canada's two largest cities.

Ambient ultrafine particles exacerbate oxygen desaturation during sleep in patients with chronic obstructive pulmonary disease: New insights into the effect spectrum of ultrafine particles on susceptible populations

The health effects of ultrafine particles (UFPs) are of growing global concern, but the epidemiological evidence remains limited. Sleep-disordered breathing (SDB) characterized by hypoxemia is a prevalent condition linked to many debilitating chronic diseases. However, the role of UFPs in the development of SDB is lacking. Therefore, this prospective panel study was performed to specifically investigate the association of short-term exposure to UFPs with SDB parameters in patients with chronic obstructive pulmonary disease (COPD). Ninety-one COPD patients completed 226 clinical visits in Beijing, China. Personal exposure to ambient UFPs of 0-7 days was estimated based on infiltration factor and time-activity pattern. Real-time monitoring of sleep oxygen saturation, spirometry, respiratory questionnaires and airway inflammation detection were performed at each clinical visit. Generalized estimating equation was used to estimate the effects of UFPs. Exposure to UFPs was significantly associated with increased oxygen desaturation index (ODI) and percent of the time with oxygen saturation below 90 % (T90), with estimates of 21.50 % (95%CI: 6.38 %, 38.76 %) and 18.75 % (95%CI: 2.83 %, 37.14 %), respectively, per 3442 particles/cm3 increment of UFPs at lag 0-3 h. Particularly, UFPs' exposure within 0-7 days was positively associated with the concentration of alveolar nitric oxide (CaNO), and alveolar eosinophilic inflammation measured by CaNO exceeding 5 ppb was associated with 29.63 % and 33.48 % increases in ODI and T90, respectively. In addition, amplified effects on oxygen desaturation were observed in current smokers. Notably, individuals with better lung function and activity tolerance were more affected by ambient UFPs due to longer time spent outdoors. To our knowledge, this is the first study to link UFPs to hypoxemia during sleep and uncover the key role of alveolar eosinophilic inflammation. Our findings provide new insights into the effect spectrum of UFPs and potential environmental and behavioral intervention strategies to protect susceptible populations.

Impacts of environmental factors on the aetiological diagnosis and disease severity of community-acquired pneumonia in China: a multicentre, hospital-based, observational study

Environmental exposures are known to be associated with pathogen transmission and immune impairment, but the association of exposures with aetiology and severity of community-acquired pneumonia (CAP) are unclear. A retrospective observational study was conducted at nine hospitals in eight provinces in China from 2014 to 2019. CAP patients were recruited according to inclusion criteria, and respiratory samples were screened for 33 respiratory pathogens using molecular test methods. Sociodemographic, environmental and clinical factors were used to analyze the association with pathogen detection and disease severity by logistic regression models combined with distributed lag nonlinear models. A total of 3323 CAP patients were included, with 709 (21.3%) having severe illness. 2064 (62.1%) patients were positive for at least one pathogen. More severe patients were found in positive group. After adjusting for confounders, particulate matter (PM) 2.5 and 8-h ozone (O3-8h) were significant association at specific lag periods with detection of influenza viruses and Klebsiella pneumoniae respectively. PM10 and carbon monoxide (CO) showed cumulative effect with severe CAP. Pollutants exposures, especially PM, O3-8h, and CO should be considered in pathogen detection and severity of CAP to improve the clinical aetiological and disease severity diagnosis.

Concentration, speciation and risk effects of multiple environmentally sensitive trace elements in respirable fine-grained fly ash

Respirable fine-grained fly ash (RFA) is captured very inefficiently by existing air purification devices of power plant, leading to increasing concerns regarding their migration and subsequent interaction with body due to fine particle size and its complex toxic composition. Trace elements of RFA in three groups with five different sizes between 8-13 µm were analyzed in terms of available concentration, speciation and risk effects. The concentration, pollution level and ecological risk level of elements in RFA were related to particle sizes. Chronic non-carcinogenic effect risk (NER) and carcinogenic effect risk (CER) were negatively correlated with particle size. The individual weight of exposed subjects, corresponding trace elements concentration and ingestion rate in RFA were three significant variables influencing CER. NER and CER had a tenfold exaggerated effect when calculated using total element concentration of RFA. In addition to individual differences and exposure conditions, trace element properties, speciation and available concentration were the dominant factor responsible for ecological and environmental effects of trace elements in RFA, following the order As>Ni, Mn>Cr>Pb>Cu>Zn. Results of this work highlight the effects and differences of trace elements in RFA on ecology and health, and provide a basis for further pollution control and human health warning.

The impact of air pollution on asthma: clinical outcomes, current epidemiology, and health disparities

INTRODUCTION

Air pollution has been shown to have a significant impact on morbidity and mortality of respiratory illnesses including asthma.

AREAS COVERED

Outdoor air pollution consists of a mixture of individual pollutants including vehicle traffic and industrial pollution. Studies have implicated an array of individual components of air pollution, with PM2.5, NO2, SO2, and ozone being the most classically described, and newer literature implicating other pollutants such as black carbon and volatile organic compounds. Epidemiological and cohort studies have described incidence and prevalence of pollution-related asthma and investigated both acute and chronic air pollution exposure as they relate to asthma outcomes. There is an increasing body of literature tying disparities in pollution exposure to clinical outcomes. In this narrative review, we assessed the published research investigating the association of pollution with asthma outcomes, focusing on the adult population and health care disparities.

EXPERT OPINION

Pollution has multiple deleterious effects on respiratory health but there is a lack of data on individualized pollution monitoring, making it difficult to establish a temporal relationship between exposure and symptoms, thereby limiting our understanding of safe exposure levels. Future research should focus on more personalized monitoring and treatment plans for mitigating exposure.