Air Pollution and Pediatric Respiratory Hospitalizations: Effect Modification by Particle Constituents and Oxidative Potential

Long-Term PM2.5 Exposure and Upregulation of CLCA1 Expression in Nasal Epithelium from Youth with Asthma

Rationale: Little is known about long-term particulate matter 92.5 μm in aerodynamic diameter (PM2.5) exposure and airway epithelial gene expression. Objectives: To test for association between long-term PM2.5 exposure and nasal epithelial gene expression in youth with asthma. Methods: Transcriptome-wide association study (TWAS) of long-term PM2.5 in nasal epithelium from youth aged 6-20 years in the 1) Epigenetic Variation and Childhood Asthma in Puerto Ricans study (n = 182), 2) Vitamin D Kids Asthma Study (n = 58), and 3) Stress and Treatment Response in Puerto Rican and African American Children with Asthma study (n = 81). Satellite hybrid models were used to estimate PM2.5 exposure in the prior year at each participant's residence. Multivariable negative binomial regression was used for each TWAS, adjusting for age, sex, and other covariates. A meta-analysis of all TWAS results was then conducted using an inverse variance-weighted average approach. Results: Most participants (∼95%) in the meta-analysis of TWAS for PM2.5 exposure identified as Puerto Rican or Black. Long-term PM2.5 was associated with 1) upregulated expression of CLCA1 (calcium-activated chloride channel regulator 1; false discovery rate-adjusted P [FDR-P] = 0.008), SYCP2 (synaptonemal complex protein 2; FDR-P = 0.01), and CYP2A6 (cytochrome p450 family 2 subfamily A member 6; FDR-P = 0.02); and 2) downregulated expression of EDAR (ectodysplasin A receptor; FDR-P = 0.01). In a meta-analysis, CLCA1 upregulation was associated with one or more positive allergen-specific IgE (FDR-P < 0.001) and increased blood eosinophils (FDR-P < 0.001) and total IgE (FDR-P < 0.001). Conclusions: In a meta-analysis of TWASs in predominantly Puerto Rican and Black youth with asthma, long-term PM2.5 exposure was associated with upregulated airway epithelial CLCA1 expression, in turn linked to biomarkers of T2-high immunity.

Transition metals and chemical compositions determine the oxidation capacity of atmospheric particulate matters

The knowledge of the causal relationship between exposure to airborne particulate matter (PM) and respiratory-related health issues remains unsatisfactory, owing to the complexities of physical and chemical characteristics in PM. One measure that greatly lifts the complexity is oxidative potential (OP), the overall production capacity of reactive oxygen species. We analyzed PM at different size fractions from three localities, exhibiting different source emission properties and photochemical aging states. We also investigated possible causes for their OPs, which were assessed using cellular and acellular assays. We found that higher PM mass did not always yield higher OP. Instead, chemical composition, modified by photochemical alteration (particle oxidation), played a critical role in the PM's reactivity. From a pollution hot spot to a downwind country town, the PM2.5 levels (mean ± SD) were 9.3 ± 4.5, 9.7 ± 4.9, and 6.6 ± 4.7 μg/m3, respectively. In contrast, the PM mass-normalized OP values in the downwind region were approximately 20 % higher than those in the upwind region based on the cellular assay and about three times higher from the acellular assay. Enhanced PM OP is associated with atmospheric oxidation, approximated by sulfur and nitrogen oxidation ratios. We further identified transition metals, particularly copper, a single most important species group, the primary determinant to the values of OP measured, contributing directly to OP and indirectly through metal-oxides enhanced photochemical alterations to PM.

PM2.5 exposure and household income are associated with lung function abnormalities in children with sickle cell disease

RATIONALE

Cardiopulmonary dysfunction is a major contributor to mortality among persons with sickle cell disease (pwSCD). Despite this, little is known regarding environmental drivers of lung function decline.

OBJECTIVE

We hypothesized that environmental and socioeconomic variables have a significant effect on lung function in pwSCD that can be detected by spirometry.

METHODS

We retrospectively analyzed all spirometry results from pwSCD followed in the Pediatric Pulmonology clinic at the Children's Hospital of Philadelphia since 1 January 2016.

RESULTS

The study included 349 spirometry tests from 128 patients, primarily "Black or African American" (88%) and male (61%). More frequent exposure to PM2.5 above 25 μg/m3 was associated with higher odds of obstruction. Specifically, when compared to incidence of exposure to PM2.5 above 25 μg/m3 <25th percentile, both pwSCD exposed to 25th-75th percentile and pwSCD >75th percentile had higher odds of obstruction on spirometry (25th-75th: odds ratio [OR]: 9.6, p = .017; >75th: OR: 31.85, p = .002) despite correction for potential confounders. Similarly, median household income below the mean was associated with higher odds of restriction (OR: 4.37; p = .009).

CONCLUSIONS

We report higher odds of obstruction in pwSCD frequently exposed to PM2.5 concentrations above 25 μg/m3 and higher odds of restriction in pwSCD with lower household income. Our findings link spirometry patterns to modifiable risk factors indicating that there may opportunities for early intervention in pwSCD that have been referred to a pulmonology clinic. Further research is needed to assess if these findings can be generalized to the wider population of pwSCD.

Spatiotemporal distribution of oxidative potential in PM2.5 and its key components across six Chinese cities

Increasing evidence has supported that oxidative potential (OP) serves as a crucial indicator of health risk of exposure to PM2.5 over mass concentration. However, there is a lack of comparative studies across multiple cities, particularly on a fine temporal scale. In this study, we aim to investigate daily variation of ambient PM2.5 OP through simultaneous samplings in six Chinese cities for one year. Results showed that more than 60 % of the sampling days exhibited non-zero ranking difference between volume-normalized oxidative potential (OPv) and mass concentration among the six cities. Key components contributing to OPv inculde Mn, NO3-, and K+, followed by Ca2+, Al, SO42-, Cl-, Fe, and NH4+. Based on these chemical components, we developed a stepwise multivariable linear regression model (R2: 0.71) for OPv prediction. The performance of the model is comparable to both species- and sources-based ones in the literature. These findings suggest that a relatively lower daily-averaged mass concentration of PM2.5 does not necessarily indicate a lower oxidative risk. Future studies and policy developments on health benefits should also consider OPv rather than mass concentration alone. Priority could be given to sources/species that contribute significantly to oxidative potential of ambient PM2.5. SYNOPSIS: This study highlights inclusion of oxidative potential as a complementary metric for air pollution assessment and control.

Outdoor Air Pollution and Pediatric Respiratory Disease

Outdoor air pollution is ubiquitous, and no safe level of exposure has been identified for the most common air pollutants such as ozone and particle pollution. Children are uniquely more susceptible to the harms of outdoor air pollution, which can cause and exacerbate respiratory disease. Although challenging to identify the effects of outdoor air pollution on individual patients, understanding the basics of outdoor air pollution is essential for pediatric respiratory health care providers. This review covers basic information regarding outdoor air pollution, unique considerations for children, mechanisms for increased susceptibility, and association with incident and exacerbation of respiratory disease in children.

Sources of acellular oxidative potential of water-soluble fine ambient particulate matter in the midwestern United States

Ambient fine particulate matter (PM2.5) is associated with numerous health complications, yet the specific PM2.5 chemical components and their emission sources contributing to these health outcomes are understudied. Our study analyzes the chemical composition of PM2.5 collected from five distinct locations at urban, roadside and rural environments in midwestern region of the United States, and associates them with five acellular oxidative potential (OP) endpoints of water-soluble PM2.5. Redox-active metals (i.e., Cu, Fe, and Mn) and carbonaceous species were correlated with most OP endpoints, suggesting their significant role in OP. We conducted a source apportionment analysis using positive matrix factorization (PMF) and found a strong disparity in the contribution of various emission sources to PM2.5 mass vs. OP. Regional secondary sources and combustion-related aerosols contributed significantly (> 75 % in total) to PM2.5 mass, but showed weaker contribution (43-69 %) to OP. Local sources such as parking emissions, industrial emissions, and agricultural activities, though accounting marginally to PM2.5 mass (< 10 % for each), significantly contributed to various OP endpoints (10-50 %). Our results demonstrate that the sources contributing to PM2.5 mass and health effects are not necessarily same, emphasizing the need for an improved air quality management strategy utilizing more health-relevant PM2.5 indicators.

The Role of Neighborhood Air Pollution in Disparate Racial and Ethnic Asthma Acute Care Use

Rationale: The share of Black or Latinx residents in a census tract remains associated with asthma-related emergency department (ED) visit rates after controlling for socioeconomic factors. The extent to which evident disparities relate to the within-city heterogeneity of long-term air pollution exposure remains unclear. Objectives: To investigate the role of intraurban spatial variability of air pollution in asthma acute care use disparity. Methods: An administrative database was used to define census tract population-based incidence rates of asthma-related ED visits. We estimate the associations between census tract incidence rates and 1) average fine and coarse particulate matter, nitrogen dioxide (NO2), and sulfur dioxide (SO2), and 2) racial and ethnic composition using generalized linear models controlling for socioeconomic and housing covariates. We also examine for the attenuation of incidence risk ratios (IRRs) associated with race/ethnicity when controlling for air pollution exposure. Measurements and Main Results: Fine and coarse particulate matter and SO2 are all associated with census tract-level incidence rates of asthma-related ED visits, and multipollutant models show evidence of independent risk associated with coarse particulate matter and SO2. The association between census tract incidence rate and Black resident share (IRR, 1.51 [credible interval (CI), 1.48-1.54]) is attenuated by 24% when accounting for air pollution (IRR, 1.39 [CI, 1.35-1.42]), and the association with Latinx resident share (IRR, 1.11 [CI, 1.09-1.13]) is attenuated by 32% (IRR, 1.08 [CI, 1.06-1.10]). Conclusions: Neighborhood-level rates of asthma acute care use are associated with local air pollution. Controlling for air pollution attenuates associations with census tract racial/ethnic composition, suggesting that intracity variability in air pollution could contribute to neighborhood-to-neighborhood asthma morbidity disparities.

Association between exposure to specific PM2.5 constituents and environment, lifestyle, and clinical parameters in patients with COPD

This study investigated the correlation between the individual chemical constituents of particulate matter 2.5 μm (PM2.5) and respiratory parameters as well as the living environment and daily behaviors in patients with chronic obstructive pulmonary disease (COPD). Data were obtained from prospective COPD panel conducted in South Korea. Following collection via a microPEM, 18 metallic elements were determined using energy-dispersive X-ray fluorescence spectroscopy. All participants completed detailed questionnaires on living environments and lifestyle practices. Eighty-nine stable COPD patients (mean age 68.1 years; 94.4% male) were analyzed. Several constituents (titanium, aluminum, bromine, and silicone) were significantly associated with respiratory outcomes. Copper and manganese concentrations were significantly associated with the living environment. Increased ventilation time and air purifier operation were associated with lower concentrations of copper, silicone, barium, and titanium. These findings suggest varying relationships between PM2.5 constituents and clinical parameters in COPD patients, providing a basis for personalized interventions and future research.

Effects of personal exposure to the oxidative potential of PM2.5 on oxidative stress biomarkers in pregnant women

Oxidative stress is a prominent pathway for the health effects associated with fine particulate matter (PM2.5) exposure. Oxidative potential (OP) of PM has been associated to several health endpoints, but studies on its impact on biomarkers of oxidative stress remains insufficient. 300 pregnant women from the SEPAGES cohort (France) carried personal PM2.5 samplers for a week and OP was measured using ascorbic acid (AA) and dithiothreitol (DTT) assays, and normalized by 1) PM2.5 mass (OPm) and 2) sampled air volume (OPv). A pool of three urine spots collected on the 7th day of PM sampling was analyzed for biomarkers, namely 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA) and 8-isoprostaglandin-F2α (8-isoPGF2α). Associations were investigated using adjusted multiple linear regressions. OP effects were additionally investigated by stratifying by median PM2.5 concentration (14 μg m-3). In the main models, no association was observed with 8-isoPGF2α, nor MDA. An interquartile range (IQR) increase in OPmAA exposure was associated with increased 8-OHdG (percent change: 6.2 %; 95 % CI: 0.2 % to 12.6 %). In the stratified analysis, exposure to OPmAA was associated with 8-OHdG for participants exposed to low levels of PM2.5 (percent change: 11.4 %; 95 % CI: 3.3 % to 20.1 %), but not for those exposed to high levels (percent change: -1.0 %; 95 % CI: -10.6 % to 9.6 %). Associations for OPmDTT also followed a similar pattern (p-values for OPmAA-PM and OPmDTT-PM interaction terms were 0.12 and 0.11, respectively). Overall, our findings suggest that OPmAA may be associated with increased DNA oxidative damage. This association was not observed with PM2.5 mass concentration exposure. The effects of OPmAA in 8-OHdG tended to be stronger at lower (below median) vs. higher concentrations of PM2.5. Further epidemiological, toxicological and aerosol research are needed to further investigate the OPmAA effects on 8-OHdG and the potential modifying effect of PM mass concentration on this association.

Ambient Air Pollution and Outpatient Morbidities in Bronchopulmonary Dysplasia

Rationale: Bronchopulmonary dysplasia (BPD) is the most common long-term complication of prematurity. Although socioeconomic status is associated with BPD morbidities, the drivers of this association are poorly understood. In the United States, ambient air pollution (AAP) exposure is linked to both race/ethnicity and socioeconomic status. Furthermore, AAP exposure is known to have a detrimental effect on respiratory health in children. Objectives: To assess if AAP exposure is linked to BPD morbidity in the outpatient setting. Methods: Participants with BPD were recruited from outpatient clinics at Johns Hopkins University and the Children's Hospital of Philadelphia between 2008 and 2021 (N = 800) and divided into low, moderate, and high AAP exposure groups, based on publicly available U.S. Environmental Protection Agency data. Clinical data were obtained by chart review and caregiver questionnaires. Results: Non-White race, home ventilator use, and lower median household income were associated with higher degrees of air pollution exposure. After adjustment for these factors, moderate and high air pollution exposure were associated with requiring systemic steroids (odds ratio, 1.78 and 2.17, respectively) compared with low air pollution. Similarly, high air pollution exposure was associated with emergency department visits (odds ratio, 1.59). Conclusions: This study demonstrates an association between AAP exposure and BPD morbidity after initial hospital discharge. AAP exposure was closely linked to race and median household income. As such, it supports the notion that AAP exposure may be contributing to health disparities in BPD outcomes. Further studies directly measuring exposure and establishing a link between biomarkers of exposure and outcomes are prerequisites to developing targeted interventions protecting this vulnerable population.

Within-city spatial variations in long-term average outdoor oxidant gas concentrations and cardiovascular mortality: Effect modification by oxidative potential in the Canadian Census Health and Environment Cohort

Health effects of oxidant gases may be enhanced by components of particulate air pollution that contribute to oxidative stress. Our aim was to examine if within-city spatial variations in the oxidative potential of outdoor fine particulate air pollution (PM2.5) modify relationships between oxidant gases and cardiovascular mortality.

Methods

We conducted a retrospective cohort study of participants in the Canadian Census Health and Environment Cohort who lived in Toronto or Montreal, Canada, from 2002 to 2015. Cox proportional hazards models were used to estimate associations between outdoor concentrations of oxidant gases (Ox, a redox-weighted average of nitrogen dioxide and ozone) and cardiovascular deaths. Analyses were performed across strata of two measures of PM2.5 oxidative potential and reactive oxygen species concentrations (ROS) adjusting for relevant confounding factors.

Results

PM2.5 mass concentration showed little within-city variability, but PM2.5 oxidative potential and ROS were more variable. Spatial variations in outdoor Ox were associated with an increased risk of cardiovascular mortality [HR per 5 ppb = 1.028, 95% confidence interval (CI): 1.001, 1.055]. The effect of Ox on cardiovascular mortality was stronger above the median of each measure of PM2.5 oxidative potential and ROS (e.g., above the median of glutathione-based oxidative potential: HR = 1.045, 95% CI: 1.009, 1.081; below median: HR = 1.000, 95% CI: 0.960, 1.043).

Conclusion

Within-city spatial variations in PM2.5 oxidative potential may modify long-term cardiovascular health impacts of Ox. Regions with elevated Ox and PM2.5 oxidative potential may be priority areas for interventions to decrease the population health impacts of outdoor air pollution.

Gaps and future directions in research on health effects of air pollution

Despite progress in many countries, air pollution, and especially fine particulate matter air pollution (PM2.5) remains a global health threat: over 6 million premature cardiovascular and respiratory deaths/yr. have been attributed to household and outdoor air pollution. In this viewpoint, we identify present gaps in air pollution monitoring and regulation, and how they could be strengthened in future mitigation policies to more optimally reduce health impacts. We conclude that there is a need to move beyond simply regulating PM2.5 particulate matter mass concentrations at central site stations. A greater emphasis is needed on: new portable and affordable technologies to measure personal exposures to particle mass; the consideration of a submicron (PM1) mass air quality standard; and further evaluations of effects by particle composition and source. We emphasize the need to enable further studies on exposure-health relationships in underserved populations that are disproportionately impacted by air pollution, but not sufficiently represented in current studies.

Assessing the health impacts of PM2.5 and ozone pollution and their comprehensive correlation in Chinese cities based on extended correlation coefficient

The coordinated control of PM_2.5 and ozone pollution is becoming more and more important in the current and next stage of Chinese environmental pollution control. Existing studies are unable to provide sufficient quantitative assessments of the correlation of PM_2.5 and ozone pollution to support the coordinated control of the two air pollutants. This study develops a systematic method to comprehensively assess the correlation between PM_2.5 and ozone pollution, including the evaluation of the impact of two air pollutants on human health and the extended correlation coefficient (ECC) for assessing the bivariate correlation index of PM_2.5-ozone pollution in Chinese cities. According to the latest studies on epidemiology conducted in China, we take cardiovascular and cerebrovascular diseases and respiratory diseases as the ozone pollution's health burden when evaluating the health impact of ozone pollution. The results show that the health impact of PM_2.5 in China decreases by 25.9 % from 2015 to 2021, while the health impact of ozone increases by 11.8 %. The ECC of 335 cities in China shows an increasing-decreasing trend but has generally increased from 2015 to 2021. The study provides important support for an in-depth understanding of the correlation and development trend of Chinese PM_2.5 and ozone pollution by classifying the comprehensive PM_2.5-ozone correlation performances of Chinese cities into four types. China or other countries will get better environmental benefits by implementing different coordinated management approaches for different correlative types of regions based on the assessment method in this study.

Association of multiple air pollutants with oxygen saturation during sleep in COPD patients: Effect modification by smoking status and airway inflammatory phenotypes

Air pollution contributes substantially to the development of chronic obstructive pulmonary disease (COPD). To date, the effect of air pollution on oxygen saturation (SpO₂) during sleep and potential susceptibility factors remain unknown. In this longitudinal panel study, real-time SpO₂ was monitored in 132 COPD patients, with 270 nights (1615 h) of sleep SpO₂ recorded. Exhaled nitric oxide (NO), hydrogen sulfide (H₂S) and carbon monoxide (CO) were measured to assess airway inflammatory characteristics. Exposure levels of air pollutants were estimated by infiltration factor method. Generalized estimating equation was used to investigate the effect of air pollutants on sleep SpO₂. Ozone, even at low levels (<60 μg/m³), was significantly associated with decreased SpO₂ and extended time of oxygen desaturation (SpO₂ < 90%), especially in the warm season. The associations of other pollutants with SpO₂ were weak, but significant adverse effects of PM₁₀ and SO₂ were observed in the cold season. Notably, stronger effects of ozone were observed in current smokers. Consistently, smoking-related airway inflammation, characterized by higher levels of exhaled CO and H₂S but lower NO, significantly augmented the effect of ozone on SpO₂ during sleep. This study highlights the importance of ozone control in protecting sleep health in COPD patients.

Association between PM2.5-bound metals and pediatric respiratory health in Guangzhou: An ecological study investigating source, health risk, and effect

Background

The adverse effects of 2.5-μm particulate matter (PM2.5) exposure on public health have become an increasing concern worldwide. However, epidemiological findings on the effects of PM2.5-bound metals on children's respiratory health are limited and inconsistent because PM2.5 is a complicated mixture.

Objectives

Given the vulnerability of children's respiratory system, aim to pediatric respiratory health, this study evaluated the potential sources, health risks, and acute health effects of ambient PM2.5-bound metals among children in Guangzhou, China from January 2017 to December 2019.

Methods

Potential sources of PM2.5-bound metals were detected using positive matrix factorization (PMF). A health risk assessment was conducted to investigate the inhalation risk of PM2.5-bound metals in children. The associations between PM2.5-bound metals and pediatric respiratory outpatient visits were examined with a quasi-Poisson generalized additive model (GAM).

Results

During 2017–2019, the daily mean concentrations of PM2.5 was 53.39 μg/m3, and the daily mean concentrations of PM2.5-bound metals range 0.03 ng/m3 [thorium (Th) and beryllium (Be)] from to 396.40 ng/m3 [iron (Fe)]. PM2.5-bound metals were mainly contributed by motor vehicles and street dust. PM2.5-bound arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr)(VI), nickel (Ni), and lead (Pb) were found to pose a carcinogenic risk (CR). A quasi-Poisson GAM was constructed that showed there were significant associations between PM2.5 concentrations and pediatric outpatient visits for respiratory diseases. PM2.5 was significantly associated with pediatric outpatient visits for respiratory diseases. Moreover, with a 10 μg/m3 increase in Ni, Cr(VI), Ni, and As concentrations, the corresponding pediatric outpatient visits for respiratory diseases increased by 2.89% (95% CI: 2.28–3.50%), acute upper respiratory infections (AURIs) increased by 2.74% (2.13–3.35%), influenza and pneumonia (FLU&amp;PN) increased by 23.36% (20.09–26.72%), and acute lower respiratory infections (ALRIs) increased by 16.86% (15.16–18.60%), respectively.

Conclusions

Our findings showed that PM2.5 and PM2.5-bound As, Cd, Co, Cr(VI), Ni, and Pb had adverse effects on pediatric respiratory health during the study period. New strategies are required to decrease the production of PM2.5 and PM2.5-bound metals by motor vehicles and to reduce levels of street dust to reduce children's exposure to these pollutants and thereby increase child health.

Assessment of trace elements directly from archived total suspended particulate filters by laser ablation ICP-MS: A case study of South Carolina

Background

Exposure to particulate air pollution is one of the greatest environmental risk factors for adverse human health outcomes. However, the constituents that may be responsible for such adverse health effects have not been fully studied.

Methods

Total suspended particulates filters collected every 6 days in 2011 from three South Carolina locations were used in this case study. An inductively coupled plasma mass spectrometer interfaced with a laser ablation system (LA-ICP-MS) was used to directly analyze 41 inorganic elemental species on air pollution filters. Then, machine learning and multivariate statistical methods was employed to identify combinatorial patterns in the data and classify sites based on their elemental composition.

Results

Forty-one elements were assessed and 33 were used in subsequent analysis. Correlations between United States Environmental Protection Agency (US EPA)'s chemical analysis dataset and data from the current study revealed significant associations between 7/15 elements with enough variation for comparison (r between 0.28 to 0.66, p<0.05). Subsequent multivariate analyses revealed four distinct patterns in the distribution of elements by sample location throughout the year.

Conclusion

The different airborne elements may need to be assessed to understand combinations of elements which occur together over space and/or time. Such information can be helpful in planning effective counter measures and strategies to control particulate air pollution.