Indoor Air Sources of Outdoor Air Pollution: Health Consequences, Policy, and Recommendations: An Official American Thoracic Society Workshop Report.

Indoor sources of air pollution worsen indoor and outdoor air quality. Thus, identifying and reducing indoor pollutant sources would decrease both indoor and outdoor air pollution, benefit public health, and help address the climate crisis. As outdoor sources come under regulatory control, unregulated indoor sources become a rising percentage of the problem. This American Thoracic Society workshop was convened in 2022 to evaluate this increasing proportion of indoor contributions to outdoor air quality. The workshop was conducted by physicians and scientists, including atmospheric and aerosol scientists, environmental engineers, toxicologists, epidemiologists, regulatory policy experts, and pediatric and adult pulmonologists. Presentations and discussion sessions were centered on 1) the generation and migration of pollutants from indoors to outdoors, 2) the sources and circumstances representing the greatest threat, and 3) effective remedies to reduce the health burden of indoor sources of air pollution. The scope of the workshop was residential and commercial sources of indoor air pollution in the United States. Topics included wood burning, natural gas, cooking, evaporative volatile organic compounds, source apportionment, and regulatory policy. The workshop concluded that indoor sources of air pollution are significant contributors to outdoor air quality and that source control and filtration are the most effective measures to reduce indoor contributions to outdoor air. Interventions should prioritize environmental justice: Households of lower socioeconomic status have higher concentrations of indoor air pollutants from both indoor and outdoor sources. We identify research priorities, potential health benefits, and mitigation actions to consider (e.g., switching from natural gas to electric stoves and transitioning to scent-free consumer products). The workshop committee emphasizes the benefits of combustion-free homes and businesses and recommends economic, legislative, and education strategies aimed at achieving this goal.

Long-term exposure to several constituents and sources of PM2.5 is associated with incidence of upper aerodigestive tract cancers but not gastric cancer: Results from the large pooled European cohort of the ELAPSE project.

It is unclear whether cancers of the upper aerodigestive tract (UADT) and gastric cancer are related to air pollution, due to few studies with inconsistent results. The effects of particulate matter (PM) may vary across locations due to different source contributions and related PM compositions, and it is not clear which PM constituents/sources are most relevant from a consideration of overall mass concentration alone. We therefore investigated the association of UADT and gastric cancers with PM2.5 elemental constituents and sources components indicative of different sources within a large multicentre population based epidemiological study. Cohorts with at least 10 cases per cohort led to ten and eight cohorts from five countries contributing to UADT- and gastric cancer analysis, respectively. Outcome ascertainment was based on cancer registry data or data of comparable quality. We assigned home address exposure to eight elemental constituents (Cu, Fe, K, Ni, S, Si, V and Zn) estimated from Europe-wide exposure models, and five source components identified by absolute principal component analysis (APCA). Cox regression models were run with age as time scale, stratified for sex and cohort and adjusted for relevant individual and neighbourhood level confounders. We observed 1139 UADT and 872 gastric cancer cases during a mean follow-up of 18.3 and 18.5 years, respectively. UADT cancer incidence was associated with all constituents except K in single element analyses. After adjustment for NO2, only Ni and V remained associated with UADT. Residual oil combustion and traffic source components were associated with UADT cancer persisting in the multiple source model. No associations were found for any of the elements or source components and gastric cancer incidence. Our results indicate an association of several PM constituents indicative of different sources with UADT but not gastric cancer incidence with the most robust evidence for traffic and residual oil combustion.

PM2.5 and cardiovascular diseases: State-of-the-Art review.

Air pollution, especially exposure to particulate matter 2.5 (PM2.5), has been associated with an increase in morbidity and mortality around the world. Specifically, it seems that PM2.5 promotes the development of cardiovascular risk factors such as hypertension and atherosclerosis, while being associated with an increased risk of cardiovascular diseases, including myocardial infarction (MI), stroke, heart failure, and arrhythmias. In this review, we seek to elucidate the pathophysiological mechanisms by which exposure to PM2.5 can result in adverse cardiovascular outcomes, in addition to understanding the link between exposure to PM2.5 and cardiovascular events. It is hypothesized that PM2.5 functions via 3 mechanisms: increased oxidative stress, activation of the inflammatory pathway of the immune system, and stimulation of the autonomic nervous system which ultimately promote endothelial dysfunction, atherosclerosis, and systemic inflammation that can thus lead to cardiovascular events. It is important to note that the various cardiovascular associations of PM2.5 differ regarding the duration of exposure (short vs long) to PM2.5, the source of PM2.5, and regulations regarding air pollution in the area where PM2.5 is prominent. Current strategies to reduce PM2.5 exposure include personal strategies such as avoiding high PM2.5 areas such as highways or wearing masks outdoors, to governmental policies restricting the amount of PM2.5 produced by organizations. This review, by highlighting the significant impact between PM2.5 exposure and cardiovascular health will hopefully bring awareness and produce significant change regarding dealing with PM2.5 levels worldwide.

Particulate matter concentration and composition in the New York City subway system.

This study investigated the concentration and composition of particulate matter (PM2.5) in the New York City subway system. Realtime measurements, at a one-second cadence, and gravimetric measurements were performed inside train cars along 300 kilometers of nine subway lines, as well as on 333 platforms from 287 subway stations. The mean (±SD) PM2.5 concentration on the underground platforms was 142 ± 69 µg/m3 versus 29 ± 20 µg/m3 for aboveground stations. The average Concentrations inside train cars were 88 ± 14 µg/m3 when traveling through underground tunnels and platforms and 29 ± 31 µg/m3 while on aboveground tracks. The particle composition analysis of filtered samples was done using X-ray fluorescence (XRF), revealing that iron made up approximately 43% of the total PM2.5 mass on station platforms, around 126 times higher than the outdoor ambient iron concentration. Other trace elements include silicon, sulfur, copper, nickel, aluminum, calcium, barium, and manganese. Considering the very high iron content, the comparative analysis of the measured concentration versus the standards set by the Environmental Protection Agency (US EPA) is questionable since those limits are largely based on particulate matter from fossil fuel combustion. Health impact analysis of iron-based particles will complement the study results presented here.

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.

Life Expectancy and Built Environments in the U.S.: A Multilevel Analysis.

INTRODUCTION: The purpose of this study is to examine the associations between built environments and life expectancy across a gradient of urbanicity in the U.S. METHODS: Census tract‒level estimates of life expectancy between 2010 and 2015, except for Maine and Wisconsin, from the U.S. Small-Area Life Expectancy Estimates Project were analyzed in 2022. Tract-level measures of the built environment included: food, alcohol, and tobacco outlets; walkability; park and green space; housing characteristics; and air pollution. Multilevel linear models for each of the 4 urbanicity types were fitted to evaluate the associations, adjusting for population and social characteristics. RESULTS: Old housing (built before 1979) and air pollution were important built environment predictors of life expectancy disparities across all gradients of urbanicity. Convenience stores were negatively associated with life expectancy in all urbanicity types. Healthy food options were a positive predictor of life expectancy only in high-density urban areas. Park accessibility was associated with increased life expectancy in all areas, except rural areas. Green space in neighborhoods was positively associated with life expectancy in urban areas but showed an opposite association in rural areas. CONCLUSIONS: After adjusting for key social characteristics, several built environment characteristics were salient risk factors for decreased life expectancy in the U.S., with some measures showing differential effects by urbanicity. Planning and policy efforts should be tailored to local contexts.

PM2.5 and Cardiovascular Health Risks.

PM2.5 is a frequently studied particulate matter metric, due to its wide range of identified overall adverse health effects, particularly cardiovascular health risks. However, there are no clear clinical practice guidelines for air pollution in regard to the prevention of cardiovascular health risks, since most of the current medical guidelines for CVD focus on metabolic risk factors such as hyperlipidemia or diabetes. We sought to determine the relationship between PM2.5 and cardiovascular disease, cardiovascular events, and all-cause mortality by performing a systematic review and meta-analysis. We searched Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Scopus, and Web of Science from the database inception to December 2022 for studies that reported an association between PM2.5 and cardiovascular disease, cardiovascular events, and all-cause mortality. We used the DerSimonian & Laird random-effects method to pool hazard ratios or risk ratios separately from the included studies. Of the total 18 prospective studies, 7,300,591 individuals were followed for a median follow-up of 9 years. Compared to low long-term exposure to PM 2.5 levels, an increase in exposure to PM 2.5 levels resulted in an increase in all-cause mortality (HR 1.08 95% CI of 1.05-1.11, P < 0.05). Similarly, when compared to a low long-term exposure to PM 2.5 levels, an increase in exposure to PM 2.5 levels resulted in an increase in cardiovascular disease (HR 1.09, 95% CI of 1.00-1.18, P < 0.05) and an increase in cardiovascular disease mortality (HR 1.12, 95% CI of 1.07-1.18, P < 0.05). Increased exposure to PM 2.5 levels is significantly associated with an increased risk of all-cause mortality, cardiovascular disease, and cardiovascular disease mortality. Although federal primary and secondary standards are in place, those standards are not low enough to prevent CVD health effects. Clinicians should emphasize PM2.5 as a modifiable CV risk factors for their patients to potentially reduce the development of CV complications. A clinical action guideline is needed specifically for air pollution effects on CVD, and how to mitigate them.

Measuring students' exposure to particulate matter (PM) pollution across microenvironments and seasons using personal air monitors.

Particulate matter (PM) pollution is a significant concern in public health, yet children's exposure is not adequately characterized. This study evaluated PM exposures among primary school-aged children in NYS across different microenvironments. This study helps fill existing knowledge gaps by characterizing PM exposure among this population across seasons and microenvironments. Sixty students were recruited from randomly selected public primary schools representing various socioeconomic statuses. Individual real-time exposure to PM2.5 was measured continuously using AirBeam personal monitors for 48 h. Children were consistently exposed to higher PM2.5 concentrations in the fall (median: fall = 2.84, spring = 2.31, winter = 0.90 µg/m3). At school, 2.19% of PM2.5 measurements exceeded the EPA annual fine particle standard, 12 µg/m3 (winter = 7.38%, fall = 2.39%, spring = 1.38%). In classrooms, PM1-4 concentrations were higher in spring and overnight, while PM7-10 concentrations were higher in fall and school hours. At home, 37.2% of fall measurements exceeded EPA standards (spring = 10.39%, winter = 4.37%). Overall, PM2.5 levels in classrooms and during transportation never rose above the EPA standard for any significant length of time. However, PM2.5 levels routinely exceeded these standards at home, in the fall, and the evening. More extensive studies are needed to confirm these results.

Long-Term Exposure to Source-Specific Fine Particles and Mortality─A Pooled Analysis of 14 European Cohorts within the ELAPSE Project.

We assessed mortality risks associated with source-specific fine particles (PM2.5) in a pooled European cohort of 323,782 participants. Cox proportional hazard models were applied to estimate mortality hazard ratios (HRs) for source-specific PM2.5 identified through a source apportionment analysis. Exposure to 2010 annual average concentrations of source-specific PM2.5 components was assessed at baseline residential addresses. The source apportionment resulted in the identification of five sources: traffic, residual oil combustion, soil, biomass and agriculture, and industry. In single-source analysis, all identified sources were significantly positively associated with increased natural mortality risks. In multisource analysis, associations with all sources attenuated but remained statistically significant with traffic, oil, and biomass and agriculture. The highest association per interquartile increase was observed for the traffic component (HR: 1.06; 95% CI: 1.04 and 1.08 per 2.86 µg/m3 increase) across five identified sources. On a 1 µg/m3 basis, the residual oil-related PM2.5 had the strongest association (HR: 1.13; 95% CI: 1.05 and 1.22), which was substantially higher than that for generic PM2.5 mass, suggesting that past estimates using the generic PM2.5 exposure response function have underestimated the potential clean air health benefits of reducing fossil-fuel combustion. Source-specific associations with cause-specific mortality were in general consistent with findings of natural mortality.

Temperature variability associations with cardiovascular and respiratory emergency department visits in Dhaka, Bangladesh.

BACKGROUND: Greenhouse gas emissions are changing the Earth's climate, most directly by modifying temperatures and temperature variability (TV). Residents of low- and middle-income countries (LMICs) are likely more adversely affected, due to lack of air conditioning to compensate. To date, there is no local epidemiological evidence documenting the cardio-respiratory health effects of TV in Dhaka, Bangladesh, one of the most climate change vulnerable cities in the world. OBJECTIVES: We assessed short-term TV associations with daily cardiovascular disease (CVD) and respiratory emergency department (ED) visits, as well as effect modification by age and season. METHODS: TV was calculated from the standard deviations of the daily minimum and maximum temperatures over exposure days. Time-series regression modeling was applied to daily ED visits for respiratory and CVD from January 2014 through December 2017. TV effect sizes were estimated after controlling for long-term trends and seasonality, day-of-week, holidays, and daily mean relative humidity and ambient temperature. RESULTS: A 1 °C increase in TV was associated with a 1.00% (95 %CI: 0.05%, 1.96%) increase in CVD ED visits at lag 0-1 days (TV0-1) and a 2.77% (95 %CI: 0.24%, 5.20%) increase in respiratory ED visits at lag 0-7 days (TV0-7). TV-CVD associations were larger in the monsoon and cold seasons. Respiratory ED visit associations varied by age, with older adults more affected by the TV across all seasons. A 1 °C increase in TV at lag 0-7 days (TV0-7) was associated with a 7.45% (95 %CI: 2.33%, 12.57%) increase in respiratory ED visits among patients above 50 years of age. CONCLUSION: This study provided novel and important evidence that cardio-pulmonary health in Dhaka is adversely affected year-round by day-to-day increases in TV, especially among older adults. TV is a key factor that should be considered in evaluating the potential human health impacts of climate change induced temperature changes.

A hybrid satellite and land use regression model of source-specific PM2.5 and PM2.5 constituents.

Although PM2.5 mass varies in source and composition over time and space, most health effects assessment have made the inherent assumption that all PM2.5 mass has the same health implications, irrespective of composition. Nationwide estimates of source-specific PM2.5 mass and constituents at local-scale would allow for epidemiological studies and health effects assessments that consider the variability in PM2.5 characteristics in their health impact assessments. In response, we developed US models of annual exposures at the census tract level for five major PM2.5 sources (traffic, soil, coal, oil, and biomass combustion) and six trace elements (elemental carbon, sulfur, silicon, selenium, nickel, and non-soil potassium) for 2001 through 2014. We employed Absolute Factor Analysis (APCA) to derive the source-specific PM2.5 impacts at monitoring stations. Random forest algorithms that incorporated predictors derived from satellite, chemical transport model, and census tract resolution land-use data on traffic, meteorology, and emissions, which were rigorously tested by 10-fold cross-validation (CV), were then employed to estimate elemental and source-specific PM2.5 levels at non-monitoring site census-tracts over the study years. Model performances were moderate to good, with CV R2 ranging from 0.41 to 0.95. For PM2.5 sources, the highest CV R2 was attained for traffic PM2.5 (CV R2 = 0.73), followed by coal (CV R2 = 0.65), oil (CV R2 = 0.62), soil (CV R2 = 0.60), and biomass (CV R2 = 0.41). Among constituents, the CV was highest for sulfur (CV R2 = 0.95). Our analyses provided highly resolved spatial estimates of annual elemental and source-specific PM2.5 concentrations at the census-tract level, for 2001 through 2014. This dataset offers exposure estimates in support of future nationwide long-term health effects studies of source-specific PM2.5 mass and constituents, enabling epidemiological research that addresses the fact that not all particles are the same.

Particle toxicity's role in air pollution.

[Figure: see text].

Respiratory Emergency Department Visit Associations with Exposures to Fine Particulate Matter Mass, Constituents, and Sources in Dhaka, Bangladesh Air Pollution.

Rationale: To date, there is no published local epidemiological evidence documenting the respiratory health effects of source-specific air pollution in South Asia, where particulate matter ⩽2.5 µm in aerodynamic diameter (PM2.5) composition is different from past studies. Differences include more biomass and residue crop-burning emissions, which may have differing health implications. Objectives: We assessed PM2.5 associations with respiratory emergency department (ED) visits in a biomass-burning-dominated high-pollution region and evaluated their variability by pollution source and composition. Methods: Time-series regression modeling was applied to daily ED visits from January 2014 through December 2017. Air pollutant effect sizes were estimated after addressing long-term trends and seasonality, day of week, holidays, relative humidity, ambient temperature, and the effect modification by season, age, and sex. Results: PM2.5 yielded a significant association with increased respiratory ED visits (0.84%; 95% confidence interval, 0.33-1.35%) per 10-µg/m3 increase. The PM2.5 health effect size varied with season, the highest being during monsoon season, when fossil-fuel combustion sources dominated exposures. Results from a source-specific health effect analysis were also consistent with fossil-fuel PM2.5 having a larger effect size per 10 µg/m3 than PM2.5 from other sources (fossil-fuel PM2.5: 2.79% [0.33-5.31%], biomass-burning PM2.5: 1.27% [0-2.54%], and other PM2.5: 0.95% [0.06-1.85%]). Age-specific associations varied, with children and older adults being disproportionately affected by the air pollution, especially by the combustion-related particles. Conclusions: This study provided novel and important evidence that respiratory health in Dhaka is significantly affected by particle air pollution, with a greater health impact by fossil-fuel combustion-derived PM2.5.

Portable air cleaner use and biomarkers of inflammation: A systematic review and meta-analysis.

Fine particulate matter air pollution (PM2.5) is a major contributor to cardiovascular morbidity and mortality, potentially via increased inflammation. PM2.5 exposure increases inflammatory biomarkers linked to cardiovascular disease, including CRP, IL-6 and TNFα. Portable air cleaners (PACs) reduce individual PM2.5 exposure but evidence is limited regarding whether PACs also reduce inflammatory biomarkers. We performed a systematic review and meta-analysis of trials evaluating the use of PACs to reduce PM2.5 exposure and inflammatory biomarker concentrations. We identified English-language articles of randomized sham-controlled trials evaluating high efficiency particulate air filters in non-smoking, residential settings measuring serum CRP, IL-6 and TNFα before and after active versus sham filtration, and performed meta-analysis on the extracted modeled percent change in biomarker concentration across studies. Of 487 articles identified, we analyzed 14 studies enrolling 778 participants that met inclusion criteria. These studies showed PACs reduced PM2.5 by 61.5 % on average. Of the 14 included studies, 10 reported CRP concentrations in 570 participants; these showed active PAC use was associated with 7 % lower CRP (95 % CI: -14 % to 0.0 %, p = 0.05). Nine studies of IL-6, with 379 participants, showed active PAC use was associated with 13 % lower IL-6 (95 % CI: [-23 %, -3 %], p = 0.009). Six studies, with 269 participants, reported TNF-α and demonstrated no statistical evidence of difference between active and sham PAC use. Portable air cleaners that reduce PM2.5 exposure can decrease concentrations of inflammatory biomarkers associated with cardiovascular disease. Additional studies are needed to evaluate clinical outcomes and other biomarkers.