Exposure to Traffic-Related Air Pollution in Relation to Progression in Physical Disability among Older Adults

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.

Traffic related activity pattern of Chinese adults: a nation-wide population based survey

BACKGROUND

Traffic-related air pollutants lead to increased risks of many diseases. Understanding travel patterns and influencing factors are important for mitigating traffic exposures. However, there is a lack of national large-scale research.

OBJECTIVE

This study aimed to evaluate the daily travel patterns of Chinese adults and provide basic data for traffic exposure and health risk research.

METHODS

We conducted the first nation-wide survey of travel patterns of adults (aged 18 and above) in China during 2011-2012. We conducted a cross-sectional study based on a nationally representative sample of 91, 121 adults from 31 provinces in China. We characterized typical travel patterns by cluster analysis and identified the associated factors of each pattern using multiple logistic regression and generalized linear regression models.

RESULTS

We found 115 typical daily travel patterns of Chinese adults and the top 11 accounted for 94% of the population. The interaction of age, urban and rural areas, income levels, gender, educational levels, city population and temperature affect people's choice of travel patterns. The average travel time of Chinese adults is 45 ± 40 min/day, with the longest travel time by the combination of walking and car (70 min/day). Gender has the largest effect on travel time (B = -8.94, 95% CI: -8.95, -8.93), followed by city GDP (B = -4.23, 95% CI: -4.23, -4.22), urban and rural areas (B = -3.62, 95% CI: -3.63, -3.61), age (B = -2.21, 95% CI: -2.21, -2.2), educational levels (B = -1.53, 95% CI: -1.53, -1.52), city area (B = -1.4, 95% CI: -1.4, -1.39) and temperature (B = 1.21, 95% CI: 1.2, 1.21).

SIGNIFICANCE

This study was the first nation-wide study on traffic activity patterns in China, which provides basic data for traffic exposure and health risk research and provides the basis for the state to formulate transportation-related policies.

The effect of PM2.5 levels on continuum functional capability among older adults: Potential cause-effect or statistical associations

BACKGROUND

Since there is limited knowledge about health effects of the clean air policy (CAP, i.e., a series of emission-control actions) on continuum functional capacity (CFC) among the older adults on a large representative data, our research was to fill this gap.

METHODS

We used a continuous variable of airborne fine particulate matter (PM_2.5) particles as a proxy for the CAP to evaluate the linear and non-linear effect of PM_2.5 exposure on CFC of older adults, under the quasi-experimental framework of the temporal contrast between 2011 (before the CAP) and 2015 (after the CAP). Multiple environmental factors were considered and spline function was utilized to fit the spatial autocorrelations. A competing risk model was constructed to qualify the impact of PM_2.5 on multidimensional disability.

RESULTS

After adjusting for potential confounders, a J-shaped association was found between PM_2.5 concentration increase on CFC, with a threshold 2μg/m³. We also demonstrated that a 10-µg/m³ increase in PM_2.5 concentration was related to a 14.0% (95% CI:0.00, 19.00%) increment risk in the functional decline. Similarly, the competing risk model presented a hazard ratio of multidimensional disability ranging from 1.707(0.928-4.141) at 40μg/m³ concentration of PM_2.5 to 4.384 (1.970-9.755) over 80μg/m³. Stratified analyses showed that married men less than 80 years old in rural areas are more likely to be affected by PM_2.5 exposure, where the influencing mechanism of air pollutant to outdoor and indoor activities might be the potential cause.

CONCLUSION

Implementing CAP might improve CFC, prevent the occurrence of disability, and update the air policy.

Exploring the relationship between air quality and health shocks to the elderly: A retrospective cross-sectional study in China

Methods

We selected 5,172 microdata on individuals from the China Health and Retirement Longitudinal Study (CHARLS) 2018. The binary logit model, the ordered logit model, and the stepwise regression were employed to compare the effects of air pollution on self-rated health (SRH) and activities of daily living (ADL) in an elderly population. The effects on health shocks were explored in different age groups, different gender groups, different regions and different sources of pollutants, respectively.

Results

We found that air pollution significantly increased the risk of health shocks in the elderly population, especially in the 60–69 year age group, and the eastern/central region, where NO2 and O3 were important pollutant sources.

Conclusion

Targeted management of the environment is necessary to improve the health status of China's elderly population. In addition, paying attention to the health status of vulnerable populations is needed to achieve social equity.

Air pollution, human capital, and urban innovation in China

Air pollution and urban innovation are two important issues that have accompanied China's economic growth in the past decade. Based on the quasi-natural experiment of central heating in northern China in winter, this paper uses regression discontinuity design (RDD) to isolate the causal relationship between air pollution and urban innovation in China by matching urban data with multiple micro databases. Further, the possible influencing mechanism is discussed from the perspective of human capital. The results show that-air pollution significantly inhibits urban innovation-specifically, a 1% increase in air pollution significantly reduces urban innovation by 1.463%; compared with non-invention patents, air pollution has a more obvious inhibitory effect on invention patents with higher innovation capacity requirements and technology content. In terms of the impact mechanism, air pollution may undermine urban innovation by impairing healthy human capital and increasing the emigration of high-level human capital from cities.

Long-term exposure to nitrogen dioxide air pollution and breast cancer risk: A nested case-control within the French E3N cohort study

Nitrogen dioxide (NO₂) is an important air pollutant due to its adverse effects on human health. Yet, current evidence on the association between NO₂ and the risk of breast cancer lacks consistency. In this study, we investigated the association between long-term exposure to NO₂ and breast cancer risk in the French E3N cohort study. Association of breast cancer risk with NO₂ exposure was assessed in a nested case-control study within the French E3N cohort including 5222 breast cancer cases identified over the 1990-2011 follow-up period and 5222 matched controls. Annual mean concentrations of NO₂ at participants' residential addresses for each year from recruitment 1990 through 2011, were estimated using a land use regression (LUR) model. Multivariable conditional logistic regression models were used to compute odds ratios (ORs) and their 95% confidence intervals (CIs). Additional analyses were performed using NO₂ concentrations estimated by CHIMERE, a chemistry transport model. Overall, the mean NO₂ exposure was associated with an increased risk of breast cancer. In all women, for each interquartile range (IQR) increase in NO₂ levels (LUR: 17.8 μg/m³), the OR of the model adjusted for confounders was 1.09 (95% CI: 1.01-1.18). The corresponding OR in the fully adjusted model (additionally adjusted for established breast cancer risk factors) was 1.07 (95% CI: 0.98-1.15). By menopausal status, results for postmenopausal women were comparable to those for all women, while no association was observed among premenopausal women. By hormone receptor status, the OR of estrogen receptor positive breast cancer = 1.07 (95% CI: 0.97-1.19) in the fully adjusted model. Additional analyses using the CHIMERE model showed slight differences in ORs estimates. The results of this study indicate an increased risk of breast cancer associated with long-term exposure to NO₂ air pollution. Observing comparable effects of NO₂ exposure estimated by two different models, reinforces these findings.

Associations of Household Solid Fuel Use With Falls and Fall-Related Injuries in Middle-Aged and Older Population in China: A Cohort Study

Objective: This study evaluated the associations of solid fuels with incidence of falls and fall-related injuries. Methods: Data were taken from wave 1∼4 of the China Health and Retirement Longitudinal Study, including 15,651 participants aged 45 years and older. Modified Poisson regression was used to examine the associations of solid fuels with falls and fall-related injuries. Results: Modified Poisson regression analysis showed that solid fuels users for cooking had an increasing incidence of falls and fall-related injuries, with RR of 1.211 (95% CI: 1.124, 1.305) and 1.248 (95% CI: 1.107, 1.408); for heating had an incidence, with RR of 1.178 (95% CI: 1.062, 1.306) and 1.134 (95% CI: 0.963, 1.335); combined for cooking and heating, with RR of 1.247 (95% CI: 1.105, 1.408) and 1.185 (95% CI: 0.982, 1.431). Conclusion: Our study suggests that solid fuel use is associated with a higher incidence of falls and fall-related injuries among adults aged 45 years and older in China. It is necessary to restrict solid fuel use to reduce household air pollution and make stronger environmental protection policies to improve household environment.

The influence of environmental awareness and conditions on successful aging: Evidence of air and water pollution in China

This study examines three aspects of successful aging including subjective health, cognitive ability, and social participation and their relations with environmental conditions and environmental awareness. We used the seemingly uncorrelated regression and multilevel models to estimate the joint relationship by combining the Chinese General Social Survey (2013 and 2021) (N = 5404 and 1580 accordingly) and the Chinese Statistical Yearbook and used propensity score analysis to identify potential endogenous issues. The first finding is that older people who were men, married, lived in urban areas, or received social security had an edge in aging successfully. Secondly, the adverse effects of environmental pollution on older adults' cognitive ability and social participation can be reduced by the protective effects of environmental awareness. Additionally, air pollution had more apparent effects, and water pollution was more modest in social involvement. This study offers empirical results to enhance the well-being of the older population by lifting their environmental perception and improving environmental quality.

The impact of air pollution on physical disability in a middle-aged and older Chinese population using regression discontinuity design

Emerging evidence has shown the association between ambient air pollution exposure and comorbid chronic diseases, which can subsequently impair physical function. However, less is known about the causal and contextual effect of air pollution on physical disability. Using data from the China Health and Retirement Longitudinal Study (CHARLS), this study employs a geographical regression discontinuity design based on the Huai River Policy to estimate the impact of ambient air pollution on physical disability in activities of daily living (ADL) in China. We find that a 10 μg/m³ increase in particulate matter [particulate matter smaller than 10 μm (PM₁₀)] leads to a 5.4% increase in the incidence of physical disability among middle-aged and older adults. This result is robust to using alternative measurement of key variables, different bandwidths and polynomial functions, and adjustment for a set of sociodemographic covariates. Stroke might be one of the potential pathological pathways linking air pollution and physical disability, with a 10 μg/m³ increase in PM₁₀ leading to a 4.7% increase in the incidence of stroke. In heterogeneity analyses, we find that older adults, males, urban residents, and people with lower socioeconomic status are more vulnerable to air pollution. These results contribute to the limited evidence on the causal and contextual effect of air pollution on physical health, and further provide policy implications for air quality control and health protection for vulnerable populations.

Associations between household solid fuel use and activities of daily living trajectories: A nationwide longitudinal study of middle and older adults in China

BACKGROUND

More studies focus on reporting the effects of ambient air pollution on physical activity while ignoring the hazards of indoor air pollution caused by household solid fuel use. Moreover, the impact of individual cognitive and depressive status on the health effects of air pollution is often overlooked.

OBJECTIVE

We examined the association between household solid fuel and activities of daily living (ADL) trajectories, and further examined this association in homogeneous subgroups of cognitive or depressive trajectories.

METHODS

Participants were from the China Health and Retirement Longitudinal Study, which conducted four waves of surveys from 2011 to 2018. We collected information on participants' household fuel use, then the ADL, cognitive and depressive performances were assessed in each wave. The latent growth mixture model (LGMM) was used to identify the optimal trajectory class for ADL, cognition, and depression. Then, the multinomial logistic regression was used to assess the association between solid fuel use and ADL trajectories in total population, as well as subgroups with different cognitive or depression trajectories. Furthermore, we examined the association between switching household fuel types and ADL trajectories across the four-wave survey.

RESULTS

The study sample included 7052 participants. We identified three ADL trajectory classes in total population: "Low-stable", "Moderate-anterior rise", and "Moderate-posterior rise". The multinomial logistic regression results showed that solid fuel use was associated with elevated odds for the adverse ADL trajectories, and this association was still shown in homogeneous subgroups of cognitive or depressive trajectories, while some effects were less significant. In addition, the risk of adverse ADL trajectories generally increases with the times of solid fuel use across the four-wave survey.

CONCLUSIONS

For middle and older adults in China, household solid fuel use was not conducive to physical activity development, which inspires that a further transformation to cleaner fuels is an important intervention.

Association between exposure level of air pollutants and incidence rate of circulatory disease in residential and industrial areas of South Korea

This study investigated the correlation between the concentration of air pollutants in two metropolitan cities, Seoul and Incheon, located in South Korea with different urban characteristics and the number of patients with circulatory diseases among residents exposed to air pollution. The residential area was selected as Eunpyeong-gu of Seoul Metropolitan City and the industrial area as Jung-gu of Incheon Metropolitan City. The evaluation period is between 2015 and 2016. The relevant data provide by the Korea governmental agency were analysed to derive the purpose of this study. It was confirmed that PM₁₀, PM_2.5, nitrogen dioxide, carbon monoxide, and sulfur dioxide among air pollutants had an increasing impact on the incidence rate of circulatory diseases. The PM_2.5 was positively correlated with the incidence rate of all circulatory diseases in residential area (p < 0.05). The carbon monoxide showed a positive correlation with circulatory system diseases except for hypertension in residential area. (p < 0.05). The sulfur dioxide was positively correlated with all circulatory diseases in both residential and industrial area (p < 0.05). Based on the results obtained from this study, it was found that there are different types of air pollutants that affect circulatory diseases in residential and industrial areas.

Associations of Heavy Metals with Activities of Daily Living Disability: An Epigenome-Wide View of DNA Methylation and Mediation Analysis

BACKGROUND

Exposure to heavy metals has been reported to be associated with multiple diseases. However, direct associations and potential mechanisms of heavy metals with physical disability remain unclear.

OBJECTIVES

We aimed to quantify associations of heavy metals with physical disability and further explore the potential mechanisms of DNA methylation on the genome scale.

METHODS

A cross-sectional study of 4,391 older adults was conducted and activities of daily living (ADL) disability were identified using a 14-item scale questionnaire including basic and instrumental activities to assess the presence of disability (yes or no) rated on a scale of dependence. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated to quantify associations between heavy metals and ADL disability prevalence using multivariate logistic regression and Bayesian kernel machine regression (BKMR) models. Whole blood-derived DNA methylation was measured using the HumanMethylationEPIC BeadChip array. An ADL disability-related epigenome-wide DNA methylation association study (EWAS) was performed among 212 sex-matched ADL disability cases and controls, and mediation analysis was further applied to explore potential mediators of DNA methylation.

RESULTS

Each 1-standard deviation (SD) higher difference in log10-transformed manganese, copper, arsenic, and cadmium level was significantly associated with a 14% (95% CI: 1.05, 1.24), 16% (95% CI:1.07, 1.26), 22% (95% CI:1.13, 1.33), and 15% (95% CI:1.06, 1.26) higher odds of ADL disability, which remained significant in the multiple-metal and BKMR models. A total of 85 differential DNA methylation sites were identified to be associated with ADL disability prevalence, among which methylation level at cg220000984 and cg23012519 (annotated to IRGM and PKP3) mediated 31.0% and 31.2% of manganese-associated ADL disability prevalence, cg06723863 (annotated to ESRP2) mediated 32.4% of copper-associated ADL disability prevalence, cg24433124 (nearest to IER3) mediated 15.8% of arsenic-associated ADL disability prevalence, and cg07905190 and cg17485717 (annotated to FREM1 and TCP11L1) mediated 21.5% and 30.5% of cadmium-associated ADL disability prevalence (all p<0.05).

DISCUSSION

Our findings suggested that heavy metals contributed to higher prevalence of ADL disability and that locus-specific DNA methylation are partial mediators, providing potential biomarkers for further cellular mechanism studies. https://doi.org/10.1289/EHP10602.

Does long-term exposure to air pollution impair physical and mental health in the middle-aged and older adults? - A causal empirical analysis based on a longitudinal nationwide cohort in China

The world is aging, posing a challenge to public health. Air pollution is increasingly recognized as an important environmental risk factor, with effects on both physical and mental health. Considering the vulnerability of older adults, they tend to have more prevalent comorbidities that may lead to broader consequences. However, evidence to comprehensively assess the causal effects of long-term air pollution exposure on the physical and mental health of older adults remains limited and inconsistent, especially in developing countries. The longitudinal data from the Chinese Family Panel Study (a representative Chinese national cohort study) for 2012, 2014, 2016, and 2018 were included in this study. The Correlated Random Effects Control Function method (CRE-CF) in a counterfactual causal inference framework was employed to explore the causal relationship between long-term exposure to air pollution and physical and mental health and self-rated health status in middle-aged and older adults, considering the ordered categorical nature of health outcomes. The appropriate instrumental variable was selected and validated. This study included 5846 participants aged >45 years in 2012. In the CRE-CF model for activities of daily living (ADLs, positively associated with physical health), subjective memory impairment (SMI, negatively associated with memory health) and self-rated health status in middle-age and older adults, the coefficient of PM_2.5 is -0.069, 0.102, and 0.106 respectively, and all statistically significant at 5% level, which suggests that chronic exposure to air pollutants had significant negative effects on ADLs, SMI and self-rated health in middle-aged and older adults. The findings suggest that long-term exposure to air pollutants can impair the health of middle-aged and older adults across the board, including physical and mental health. In the context of an aging society, the findings of this study will provide tremendous implications for the authority to protect them from damage caused by long-term exposure to air pollutants.

Residential proximity to major roadway and progression in physical disability in older adults in China

Evidence of a connection between living near major roadway and adverse health outcome has come to light. However, little is known about the effect of residential traffic exposure on aging-related physical disability and whether this effect can be modified. We used data derived from Chinese Longitudinal Healthy Longevity Surveys in 2018, with a total of 15,771 participants aged ≥ 65. Residential proximity to major roadway was used as a surrogate for traffic-related air pollution and physical function was measured using basic and instrumental activities of daily living. Logistic regression models were adopted for the analyses. Compared with those living > 300 m from major road, participants living within 200 m had higher risk of poorer physical functioning. The peak odds ratio was observed in severe disability caused by 101-200 m distance (OR = 1.34, 95% CI: 1.08, 1.66). And this association got stronger with longer duration of living close to major road. In dichotomized analyses using 200 m as a cutoff point, the effect associated with living close to major road was greater in male and current smoker. Specially, poor physical function appears earlier in female, but less severe than that in male. The result emphasizes the adverse effect of residential proximity to major roadways to aging-related declines in health-especially for basic living ability. This association was more pronounced in male and current smokers, which cannot be reversed by lowering the indoor air pollution.

Association between Ambient Fine Particulate Matter and Physical Functioning in Middle-aged and Older Chinese Adults: A Nationwide Longitudinal Study

BACKGROUND

Exposure to air pollution is associated with several chronic diseases and subclinical processes that could subsequently contribute to physical disability. However, whether and to what extent air pollution exposure is associated with objective measures of physical functioning remains understudied.

METHODS

We used longitudinal data from the China Health and Retirement Longitudinal Study (CHARLS) and included 10,823 participants who were surveyed at least twice. Annual average exposure to fine particulate matter (PM2.5) was assessed using a state-of-the-art estimator. Physical functioning was assessed with four objective tests covering hand-grip strength, balance, repeated chair stands, and gait speed. Mixed-effects models with participants as a random term were used to estimate associations with multiple adjustments.

RESULTS

We found a significant and robust association between exposure to increased PM2.5 and the reduction in hand-grip strength and balance ability. Each 10-μg/m 3 increase in annual averaged concentrations of PM2.5 was associated with a 220-g (95% confidence interval [CI]: 127, 312 g) reduction in hand-grip strength per 60 kg of body weight and a 5% risk (95% CI: 2, 7) of reduced balance ability. The estimated effect of each 10-μg/m 3 increase in PM2.5 on hand-grip strength and balance ability was equivalent to the effect of aging [1.12 (95% CI: 0.76, 1.48) and 0.98 (95% CI: 0.50, 1.50) years, respectively].

CONCLUSIONS

PM2.5 may be differentially associated with various dimensions of physical functioning. Improving air quality can prevent physical disability.

Children and Youth Environmental Action: The Case of Children and Youth with Disabilities

Youth environmental activism is on the rise. Children and youth with disabilities are disproportionally impacted by environmental problems and environmental activism. They also face barriers towards participating in activism, many of which might also apply to their participation in environmental activism. Using a scoping review approach, we investigated the engagement with children and youth with disabilities by (a) academic literature covering youth environmental activism and their groups and (b) youth environmental activism group (Fridays For Future) tweets. We downloaded 5536 abstracts from the 70 databases of EBSCO-HOST and Scopus and 340 Fridays For Future tweets and analyzed the data using directed qualitative content analysis. Of the 5536 abstracts, none covered children and youth with disabilities as environmental activists, the impact of environmental activism or environmental problems such as climate change on children and youth with disabilities. Fourteen indicated that environmental factors ‘caused’ the ‘impairments’ in children and youth with disabilities. One suggested that nature could be beneficial to children and youth with disabilities. The tweets did not mention children and youth with disabilities. Our findings suggest the need for more engagement with children and youth with disabilities in relation to youth environmental activism and environmental challenges.

Exposure to Air Pollution in Relation to Risk of Dementia and Related Outcomes: An Updated Systematic Review of the Epidemiological Literature

BACKGROUND

Dementia is a devastating neurologic condition that is common in older adults. We previously reviewed the epidemiological evidence examining the hypothesis that long-term exposure to air pollution affects dementia risk. Since then, the evidence base has expanded rapidly.

OBJECTIVES

With this update, we collectively review new and previously identified epidemiological studies on air pollution and late-life cognitive health, highlighting new developments and critically discussing the merits of the evidence.

METHODS

Using a registered protocol (PROSPERO 2020 CRD42020152943), we updated our literature review to capture studies published through 31 December 2020, extracted data, and conducted a bias assessment.

RESULTS

We identified 66 papers (49 new) for inclusion in this review. Cognitive level remained the most commonly considered outcome, and particulate matter (PM) remained the most commonly considered air pollutant. Since our prior review, exposure estimation methods in this research have improved, and more papers have looked at cognitive change, neuroimaging, and incident cognitive impairment/dementia, though methodological concerns remain common. Many studies continue to rely on administrative records to ascertain dementia, have high potential for selection bias, and adjust for putative mediating factors in primary models. A subset of 35 studies met strict quality criteria. Although high-quality studies of fine particulate matter with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 ) and cognitive decline generally supported an adverse association, other findings related to PM 2.5 and findings related to particulate matter with aerodynamic diameter ≤ 10 μ m (PM 10 , NO 2 , and NO x ) were inconclusive, and too few papers reported findings with ozone to comment on the likely direction of association. Notably, only a few findings on dementia were included for consideration on the basis of quality criteria.

DISCUSSION

Strong conclusions remain elusive, although the weight of the evidence suggests an adverse association between PM 2.5 and cognitive decline. However, we note a continued need to confront methodological challenges in this line of research. https://doi.org/10.1289/EHP8716.

An Assessment on Ethanol-Blended Gasoline/Diesel Fuels on Cancer Risk and Mortality

Although cancer is traditionally considered a genetic disease, the epigenetic abnormalities, including DNA hypermethylation, histone deacetylation, and/or microRNA dysregulation, have been demonstrated as a hallmark of cancer. Compared with gene mutations, aberrant epigenetic changes occur more frequently, and cellular epigenome is more susceptible to change by environmental factors. Excess cancer risks are positively associated with exposure to occupational and environmental chemical carcinogens, including those from gasoline combustion exhausted in vehicles. Of note, previous studies proposed particulate matter index (PMI) as a measure for gasoline sooting tendency, and showed that, compared with the other molecules in gasoline, 1,2,4-Trimethylbenzene, 2-methylnaphthalene and toluene significantly contribute to PMI of the gasoline blends. Mechanistically, both epigenome and genome are important in carcinogenicity, and the genotoxicity of chemical agents has been thoroughly studied. However, less effort has been put into studying the epigenotoxicity. Moreover, as the blending of ethanol into gasoline substitutes for carcinogens, like benzene, toluene, xylene, butadiene, and polycyclic aromatic hydrocarbons, etc., a reduction of secondary aromatics has been achieved in the atmosphere. This may lead to diminished cancer initiation and progression through altered cellular epigenetic landscape. The present review summarizes the most important findings in the literature on the association between exposures to carcinogens from gasoline combustion, cancer epigenetics and the potential epigenetic impacts of biofuels.

The effects of household solid fuel use on self-reported and performance-based physical functioning in middle-aged and older Chinese populations: A cross-sectional study

BACKGROUND

Physical limitation, which has been linked to outdoor air pollution exposure in previous studies, is a risk factor for disability and even for premature death. Although people often spend more time indoors, the relationship between indoor air pollution and physical function has not been fully explored.

METHODS

The associations of household fuel types with self-reported and performance-based physical functioning were tested on a total of 12,458 participants in the China Health and Retirement Longitudinal Study (CHARL), using generalized linear models and logistic regression models. Additionally, subgroup analyses according to smoking status and number of chronic diseases, were performed regarding these associations.

RESULTS

Our results revealed that after adjusting for potential confounds, solid fuel use in cooking showed -0.08 (-0.13, -0.04) and -0.15 (-0.23, -0.06) declines in self-reported and performance-based physical functioning scores (higher scores means fewer physical limitations), when compared with cleaner groups, respectively. Considering these outcomes as binary variables, the ORs (95% CIs) for abnormal self-reported and performance-based physical functioning in the solid fuel cooking group were 1.226 (1.053-1.427) and 1.194 (1.072-1.330), respectively. No significant association between heating fuel use and physical functioning was observed. Additionally, no modification effect of smoking status and the number of chronic diseases on the association between cooking fuel use and performance-based physical functioning was observed (P > 0.05).

CONCLUSION

Our findings suggested that solid cooking fuel use may be associated with self-reported and performance-based physical functioning decline of middle-aged and elder Chinese populations.

Protocol to assess the efficacy of carnosine supplementation in mitigating the adverse cardiovascular responses to particulate matter (PM) exposure: the Nucleophilic Defense Against PM Toxicity (NEAT) trial

INTRODUCTION

Exposure to airborne particulate matter (PM) is associated with cardiovascular disease. These outcomes are believed to originate from pulmonary oxidative stress and the systemic delivery of oxidised biomolecules (eg, aldehydes) generated in the lungs. Carnosine is an endogenous di-peptide (β-alanine-L-histidine) which promotes physiological homeostasis in part by conjugating to and neutralising toxic aldehydes. We hypothesise that an increase of endogenous carnosine by dietary supplementation would mitigate the adverse cardiovascular outcomes associated with PM exposure in humans.

METHODS AND ANALYSIS

To test this, we designed the Nucleophilic Defense Against PM Toxicity trial. This trial will enroll 240 participants over 2 years and determine if carnosine supplementation mitigates the adverse effects of PM inhalation. The participants will have low levels of endogenous carnosine to facilitate identification of supplementation-specific outcomes. At enrollment, we will measure several indices of inflammation, preclinical cardiovascular disease and physical function. Participants will be randomly allocated to carnosine or placebo groups and instructed to take their oral supplement for 12 weeks with two return clinical visits and repeated assessments during times of peak PM exposure (June-September) in Louisville, Kentucky, USA. Statistical modelling approaches will be used to assess the efficacy of carnosine supplementation in mitigating adverse outcomes.

ETHICS AND DISSEMINATION

This study protocol has been approved by the Institutional Review Board at the University of Louisville. Results from this study will be disseminated at scientific conferences and in peer-reviewed publications.Trial registration: NCT03314987; Pre-results.

Household heating associated with disability in activities of daily living among Chinese middle-aged and elderly: a longitudinal study

Background

The health hazards of indoor air pollution are well-established but studies of the health effects due to pollution from heating are rare. This study investigated the association of heating and disability for activities of daily living among Chinese middle-aged and elderly.

Methods

We used two consecutive surveys in a cohort of over 17,000 adults aged 45 or older, who were interviewed first in 2011–2012 and then in 2013. In these surveys, taking advantage of random survey time, we applied a random effects logit regression model that included an interaction between pollution-producing heating fuel and a dummy variable, which measured interview time based on whether or not it was heating season.

Results

Exposure to pollution-producing heating fuel was associated with a 39.9% (OR 1.399; 95%CI 1.227–1.594) and 71.0% (OR 1.710; 95%CI 1.523–1.920) increase in the likelihood of disability in activities of daily living (DADL) and disability in instrumental activities of daily living (DIADL), respectively. In heating season between year 2011 and 2013, moving from clean heating energy for heating to pollution-producing fuel was linked with an increase in the likelihoods having DADL and DIADL, with the OR of 2.014 (95%CI 1.126–3.600) and 1.956 (95%CI 1.186–3.226), respectively. However, disability increases due to change from clean energy to pollution-producing heating energy did not appear in advantaged education respondents.

Conclusions

We found that exposure to heating by burning of coal, wood, or crop residue was associated with disability in performing daily living activities. Health policymakers should take indoor pollution due to heating into consideration as it is a major determinant of activities of daily living in elderly people; especially, such policy should focus on elderly people who have disadvantaged education.

Associations between perceived environmental pollution and health-related quality of life in a Chinese adult population

BACKGROUND

Health-related quality of life (HRQoL) measures are being used in increasingly diverse populations. However, there have no known studies to date to examine the associations between perceived environmental pollution and HRQoL in a Chinese population. This study aimed to report the associations between air, water, noise pollution and HRQoL among Chinese adult population.

METHODS

A cross-sectional survey data was used from East Asian Social Survey 2010 with a sample of 3866 Chinese populations regarding environmental pollution. HRQoL was computed by SF-12 and reflected by physical and mental component summary score (PCS & MCS). Ordinary least regression analyses were used to examine associations between perceived environmental pollution and PCS and MCS scores. Models in SPSS PROCESS were selected to demonstrate the moderating and mediating effects.

RESULTS

Only considering one pollutant, perceived air pollution and perceived water pollution had significant associations with PCS and MCS scores. Perceived noise pollution had significant associations with PCS scores. Perceived air×noise, air×water, noise×water, and air×noise×water pollution had significant associations with PCS and MCS scores. Conditional (moderated) mediation showed that there were no moderating effects and mediating effects of perceived one pollutant on another pollutant.

CONCLUSIONS

Co-occurring perceived environmental pollution were mainly associated with progressive increase in PCS and MCS scores among the Chinese adult population. These results suggested that some effective policies should be carried out to improve environmental quality in Chinese adult population.

Long-term exposure to PM2.5 and incidence of disability in activities of daily living among oldest old

Currently the Chinese government has adopted World Health Organization interim target-1 values as the national ambient air quality standards values. However, the population-based evidence was insufficient, especially for the oldest old (aged 80+). We evaluated the association of fine particulate matters (PM_2.5) exposure and incidence of disability in activities of daily living (ADL) in 15 453 oldest old in 886 counties/cities in China from 2002 to 2014 using Cox model with penalized splines and competing risk models to evaluate the linear or non-linear association. After adjusting for potential confounders, a J-shaped association existed between PM_2.5 exposure with a threshold concentration of 33 μg/m³, and incident disability in ADL. Above this threshold, the risk magnitude significantly increased with increase of PM_2.5 concentrations; compared to 33 μg/m³, the hazard ratio ranged from 1.03 (1.00-1.06) at 40 μg/m³ to 2.25 (1.54-3.29) at 110 μg/m³. The risk magnitude was not significantly changed below this threshold. Each 10 μg/m³ increase in PM_2.5 exposure corresponded to a 7.7% increase in the risk of disability in ADL (hazard ratio 1.077, 95% CI 1.051-1.104). Men, smokers, and participants with cognitive impairment might be more vulnerable to PM_2.5 exposure. The study provided limited population-based evidence for the oldest old and detected a threshold of 33 μg/m³, and supported that reduction to current World Health Organization interim target-1value (35 μg/m³) and Chinese national ambient air quality standards (35 μg/m³) or lower may be associated with lower risk of disability in ADL.

Estimating exposure to fine particulate matter emissions from vehicle traffic: Exposure misclassification and daily activity patterns in a large, sprawling region

Vehicle traffic is responsible for a significant portion of toxic air pollution in urban areas that has been linked to a wide range of adverse health outcomes. Most vehicle air quality analyses used for transportation planning and health effect studies estimate exposure from the measured or modeled concentration of an air pollutant at a person's home. This study evaluates exposure to fine particulate matter from vehicle traffic and the magnitude and cause of exposure misclassification that result from not accounting for population mobility during the day in a large, sprawling region. We develop a dynamic exposure model by integrating activity-based travel demand, vehicle emission, and air dispersion models to evaluate the magnitude, components and spatial patterns of vehicle exposure misclassification in the Atlanta, Georgia metropolitan area. Overall, we find that population exposure estimates increase by 51% when population mobility is accounted for. Errors are much larger in suburban and rural areas where exposure is underestimated while exposure may be overestimated near high volume roadways and in the urban core. Exposure while at work and traveling account for much of the error. We find much larger errors than prior studies, all of which have focused on more compact urban regions. Since many people spend a large part of their day away from their homes and vehicle emissions are known to create "hotspots" along roadways, home-based exposure is unlikely to be a robust estimator of a person's actual exposure. Accounting for population mobility in vehicle emission exposure studies may reveal more effective mitigation strategies, important differences in exposure between population groups with different travel patterns, and reduce exposure misclassification in health studies.

Enhancing Models and Measurements of Traffic-Related Air Pollutants for Health Studies Using Dispersion Modeling and Bayesian Data Fusion

INTRODUCTION

The adverse health effects associated with exposure to traffic-related air pollutants (TRAPs) remain a key public health issue. Often, exposure assessments have not represented the small-scale variation and elevated concentrations found near major roads and in urban settings. This research explores approaches aimed at improving exposure estimates of TRAPs that can reduce exposure measurement error when used in health studies. We consider dispersion models designed specifically for the near-road environment, as well as spatiotemporal and data fusion models. These approaches are implemented and evaluated utilizing data collected in recent modeling, monitoring, and epidemiological studies conducted in Detroit, Michigan.

APPROACH

Dispersion models, which estimate near-road pollutant concentrations and individual exposures based on first principles - and in particular, high fidelity models - can provide great flexibility and theoretical strength. They can represent the spatial variability of TRAP concentrations at locations not measured by conventional and spatially sparse air quality monitoring networks. A number of enhancements to dispersion modeling and mobile on-road emissions inventories were considered, including the representation of link-based road networks and updated estimates of temporal allocation of traffic activity, emission factors, and meteorological inputs. The recently developed Research LINE-source model (RLINE), a Gaussian line-source dispersion model specifically designed for the near-road environment, was used in an operational evaluation that compared predicted concentrations of nitrogen oxides (NOx), carbon monoxide (CO), and PM2.5 (particulate matter ≤ 2.5 µm in aerodynamic diameter) with observed concentrations at air quality monitoring stations located near high-traffic roads. Spatiotemporal and data fusion models provided additional and complementary approaches for estimating TRAP exposures. We formulated both nonstationary universal kriging models that exploit the spatial correlation in the monitoring data, and data fusion models that leverage the information contained in both the monitoring data and the output of numerical models, specifically RLINE. These models were evaluated using observations of nitric oxide (NO), NOx, black carbon (BC), and PM2.5 monitored along transects crossing major roads in Detroit. We also examined model assumptions, including the appropriateness of the covariance functions, errors in RLINE outputs, and the effects of jointly modeling two pollutants and using an updated emission inventory.

RESULTS

For CO and NOx, dispersion model performance was best when monitoring sites were close to major roads, during downwind conditions, during weekdays, and during certain seasons. The ability to discern local and particularly the traffic-related portion of PM2.5 was limited, a result of high background levels, the sparseness of the monitoring network, and large uncertainties for certain sources (e.g., area, fugitive) and some processes (e.g., formation of secondary aerosols). Sensitivity analyses of alternative meteorological inputs and updated emission factors showed some performance gain when using local (on-site) meteorological data and updated inventories. Overall, the operational evaluation suggested RLINE's usefulness for estimating spatially and temporally resolved exposure estimates. The application of the universal kriging models confirmed that wind speed and direction are important drivers of nonstationarity in pollutant concentrations, and that these models can predict exposure estimates that have lower prediction errors than do stationary model counterparts. The application of the Bayesian data fusion models suggested that the RLINE output had a spatially varying additive bias for NOx and PM2.5 and provided little additional information for NOx, besides what is already contained in traffic and geographical information system (GIS) covariates, but had improved estimates of PM2.5 concentrations. Results of the nonstationary Bayesian data fusion model that used RLINE output across a field spanning the measurement sites were similar to a regression-based Bayesian data fusion approach that used only RLINE output at the monitoring locations, with the latter being computationally less burdensome. Using the regression-based Bayesian data fusion model, we found that RLINE with the updated emission inventory provided results that were more useful for estimating NOx concentration at unmonitored sites, but the updated emission inventory did not improve predictions of PM2.5 concentrations. Joint modeling of NOx and PM2.5 was not useful, a result of differences in RLINE's utility in predicting PM2.5 and NOx - useful for the former, but not for the latter - and differences in the spatial dependence structures of the two pollutants. Overall, information provided by RLINE was shown to have the potential to improve spatiotemporal estimates of TRAP concentrations.

CONCLUSIONS

The study results should be interpreted and generalized cautiously given the limitations of the data used. Similar analyses in other settings are recommended for confirming and extending our findings. Still, the study highlights considerations that are relevant for exposure estimates used in health studies. The ability of a dispersion model to accurately reproduce and predict a pollutant depends on the pollutant as well as on spatial and temporal factors, such as the distance and direction from the road, time-of-day, and day-of-week. The nature and source of exposure measurement errors should be taken into consideration, particularly in health studies that take advantage of time- activity information that describes where and when individuals are exposed to pollution. Efforts to refine model inputs and improve model performance can be helpful; meteorological inputs may be the most critical. For both dispersion and spatiotemporal statistical models, sufficient and high-quality monitoring data are essential for developing and evaluating these models. Our analyses using Bayesian data fusion models confirm the presence of spatially varying errors in dispersion model outputs and allow quantification of both the magnitude and the spatial nature of these errors. This valuable information can be leveraged in health studies examining air pollution exposure as well as in studies informing regulatory responses.

Impacts on human mortality due to reductions in PM10 concentrations through different traffic scenarios in Paris, France

OBJECTIVES

Air pollution is a well-known burden for population health and health systems worldwide. Reduction in air pollution is associated with improvements in mortality and rates of respiratory, cardiovascular and other diseases. Though air quality is a problem globally, efforts to lower air pollutant concentrations are usually regional or local. In industrialized countries, most urban air pollution is caused by vehicles, suggesting reductions in traffic would result in reductions of pollution. However, detailed data on how such reductions can be achieved and impact public health is just beginning to emerge, and other influencing factors, including vehicle flow or urban landscape are largely unaccounted for.

METHODS

We utilized a unique combination of vehicle emission measurements combined with simulations of traffic and vehicle variations, as well as urban topographies, to quantify health impacts of PM₁₀ reduction in a single district of Paris, France, for various methods of traffic improvement. Here we rank and evaluate improvements in non-accidental mortality for thirteen possible scenarios to reduce traffic related PM₁₀ emissions.

RESULTS

The maximum impact scenario requires all passenger vehicles to meet Euro 5 standards and excludes diesel vehicles, resulting in long-term decreases in non-accidental mortality of 148.79 people per year, or 104.40 per 100,000 people. Similar reductions hold for the scenario requiring a completely electric passenger fleet, with long-term annual reductions of 137.14 premature mortalities. Removing all diesel vehicles is the third most impactful scenario, preventing 135.55 deaths yearly.

DISCUSSION

PARTLESS provides comparisons between thirteen different traffic-related air quality reduction mechanisms in terms of improvements in mortality rates. Improving emissions standards, increasing electric vehicle use and removing diesel vehicles can prevent more than 148 deaths per year in this district alone. Further improvements in mortality reduction may require changes to the composition of vehicle components, asphalt or to the management of resuspended particulate matter.

Green and blue spaces and physical functioning in older adults: Longitudinal analyses of the Whitehall II study

There is increasing evidence of the health benefits of exposure to natural environments, including green and blue spaces. The association with physical functioning and its decline at older age remains to be explored. The aim of the present study was to investigate the longitudinal association between the natural environment and the decline in physical functioning in older adults. We based our analyses on three follow-ups (2002-2013) of the Whitehall II study, including 5759 participants (aged 50 to 74 years at baseline) in the UK. Exposure to natural environments was assessed at each follow-up as (1) residential surrounding greenness across buffers of 500 and 1000 m around the participants' address using satellite-based indices of greenness (Enhanced Vegetation Index (EVI) and Normalized Difference Vegetation Index (NDVI)) and (2) the distance from home to the nearest natural environment, separately for green and blue spaces, using a land cover map. Physical functioning was characterized by walking speed, measured three times, and grip strength, measured twice. Linear mixed effects models were used to quantify the impact of green and blue space on physical functioning trajectories, controlled for relevant covariates. We found higher residential surrounding greenness (EVI and NDVI) to be associated with slower 10-year decline in walking speed. Furthermore, proximity to natural environments (green and blue spaces combined) was associated with slower decline in walking speed and grip strength. We observed stronger associations between distance to natural environments and decline in physical functioning in areas with higher compared to lower area-level deprivation. However, no association was observed with distance to green or blue spaces separately. The associations with decline in physical functioning were partially mediated by social functioning and mental health. Our results suggest that higher residential surrounding greenness and living closer to natural environments contribute to better physical functioning at older ages.

Ambient ultrafine particles activate human monocytes: Effect of dose, differentiation state and age of donors

Exposure to ambient particulate matter (PM) has been linked to adverse pulmonary and cardiovascular health effects. Activation of both inflammatory and oxidative stress pathways has been observed and may be a probable cause of these outcomes. We tested the hypothesis that in human monocytes, PM-induced oxidative and inflammatory responses are interrelated. A human monocytic cell line (THP-1) was used to determine if dose and differentiation state plays a role in the cellular response after a 24hr exposure to particles. Primary human monocytes derived from eight female, non-smoker donors (aged: 21, 24, 27, 28, 48, 49, 54 & 60yo) were used to determine if the age of donors modulates the response. Cells were treated with aqueous suspensions of ambient ultrafine particles (UFP, defined as smaller than 0.2µm in size) or a media control for 24hr. After exposure, reactive oxygen species (ROS) formation was increased irrespective of dose or differentiation state of THP-1 cells. In the primary human monocytes, ROS formation was not significantly changed. The release of the proinflammatory cytokine, tumor necrosis factor alpha (TNF-α), was dose-dependent and greatest in differentiated compared to undifferentiated THP-1 cells exposed to UFP. In the Primary human monocytes, TNF-α secretion was increased irrespective of the age of the donor. Our results suggest that after a 24hr exposure to particles, general reactive oxygen species formation was nonspecific and uncorrelated to cytokine secretion which was consistently enhanced. Cytokines play an important role in orchestrating many immune responses and thus the ability of ambient particles to enhance robust secretion of a proinflammatory cytokine from primary human monocytes, and how this may influence the response to pathogens and alter disease states, needs to be further evaluated.

Air Pollution and Performance-Based Physical Functioning in Dutch Older Adults

BACKGROUND

Functional limitations are a major cause for needing care and institutionalization among older adults. Exposure to air pollution has been suggested to be associated with increased functional limitations in older people.

OBJECTIVE

Our objective was to assess the association between air pollution and physical functioning in Dutch older adults.

METHODS

We analyzed data on performance-based (walking speed, ability to rise from a chair, putting on and taking off a cardigan, balance test) and self-reported physical functioning for 1,762 participants of the Longitudinal Aging Study Amsterdam, who participated in measurement cycles performed in 2005/2006, 2008/2009, and 2011/2012. Annual average outdoor air pollution concentrations [nitrogen dioxide (NO₂), nitrogen oxides (NO_x), particulate matter with diameters ≤2.5μm (PM_2.5), ≤10μm (PM₁₀), and 2.5-10μm (PM_coarse), and PM_2.5 absorbance] at the home address at the start of the first measurement cycle were estimated using land-use regression models. Analyses were performed using mixed models with random participant intercepts adjusting for potential confounders.

RESULTS

Exposure to most air pollutants was associated with reduced performance-based physical functioning; for example, an interquartile range increase in NO₂ exposure was associated with a 0.22 (95% confidence interval: 0.03, 0.42) lower performance test score in fully adjusted models, equivalent to the difference in performance score between participants who differed by 9 mo in age. Exposure to air pollution was generally not statistically significantly associated with self-reported functional limitations, and not associated with a faster decline in performance-based physical functioning over the study period.

CONCLUSION

This study suggests that exposure to air pollution may adversely affect physical performance of older adults in the Netherlands. https://doi.org/10.1289/EHP2239.

EFAD transgenic mice as a human APOE relevant preclinical model of Alzheimer's disease

Identified in 1993, APOE4 is the greatest genetic risk factor for sporadic Alzheimer's disease (AD), increasing risk up to 15-fold compared with APOE3, with APOE2 decreasing AD risk. However, the functional effects of APOE4 on AD pathology remain unclear and, in some cases, controversial. In vivo progress to understand how the human (h)-APOE genotypes affect AD pathology has been limited by the lack of a tractable familial AD-transgenic (FAD-Tg) mouse model expressing h-APOE rather than mouse (m)-APOE. The disparity between m- and h-apoE is relevant for virtually every AD-relevant pathway, including amyloid-β (Aβ) deposition and clearance, neuroinflammation, tau pathology, neural plasticity and cerebrovascular deficits. EFAD mice were designed as a temporally useful preclinical FAD-Tg-mouse model expressing the h-APOE genotypes for identifying mechanisms underlying APOE-modulated symptoms of AD pathology. From their first description in 2012, EFAD mice have enabled critical basic and therapeutic research. Here we review insights gleaned from the EFAD mice and summarize future directions.

Exposure to ambient PM2.5 associated with overall and domain-specific disability among adults in six low- and middle-income countries

BACKGROUND

Exposure to particulate matter pollution is associated with various cardiopulmonary diseases, which are closely related with disability. The direct relationship between air pollution and disability, however, has not been fully explored.

METHODS

We used data from 45,625 participants in the Study on global AGEing and adult health in six low- and middle-income countries. The 12-item version of the World Health Organization Disability Assessment Schedule (WHODAS 2.0) was used to measure the disability with six domains (cognition, mobility, self-care, getting along, life activities, and participation in society). Participants' community addresses were used to estimate annual concentration of PM_2.5 using satellite data. We used linear mixed models to examine the effects of PM_2.5 on overall and domain-specific WHODAS scores.

RESULTS

Exposure to PM_2.5 was significantly associated with greater disability score (a higher score implies a greater disability); each 10μg/m³ increase corresponded to 0.72 (95% CI: 0.22, 1.22) increase in overall disability score. Compared with low PM_2.5 level (<14.33μg/m³), moderate (14.33-27.83μg/m³) and high exposure levels (>27.83μg/m³) were associated with 3.43 (95% CI: 1.43, 5.43) and 3.72 (95% CI: 1.59, 5.86) increase in disability scores. Among the six domains, cognition, mobility and getting along were found to be associated with PM_2.5. Stratified analyses found that women and older subjects were more sensitive to this effect.

CONCLUSION

Exposure to ambient PM_2.5 might be one risk factor of disability in the low- and middle-income countries, women and older adults are the vulnerable population; and among the six domains, cognition, mobility and getting along are more relevant to this effect.

Traffic-derived particulate matter exposure and histone H3 modification: A repeated measures study

BACKGROUND

Airborne particulate matter (PM) may induce epigenetic changes that potentially lead to chronic diseases. Histone modifications regulate gene expression by influencing chromatin structure that can change gene expression status. We evaluated whether traffic-derived PM exposure is associated with four types of environmentally inducible global histone H3 modifications.

METHODS

The Beijing Truck Driver Air Pollution Study included 60 truck drivers and 60 office workers examined twice, 1-2 weeks apart, for ambient PM₁₀ (both day-of and 14-day average exposures), personal PM_2.5, black carbon (BC), and elemental components (potassium, sulfur, iron, silicon, aluminum, zinc, calcium, and titanium). For both PM₁₀ measures, we obtained hourly ambient PM₁₀ data for the study period from the Beijing Municipal Environmental Bureau's 27 representatively distributed monitoring stations. We then calculated a 24h average for each examination day and a moving average of ambient PM₁₀ measured in the 14 days prior to each examination. Examinations measured global levels of H3 lysine 9 acetylation (H3K9ac), H3 lysine 9 tri-methylation (H3K9me3), H3 lysine 27 tri-methylation (H3K27me3), and H3 lysine 36 tri-methylation (H3K36me3) in blood leukocytes collected after work. We used adjusted linear mixed-effect models to examine percent changes in histone modifications per each μg/m³ increase in PM exposure.

RESULTS

In all participants each μg/m³ increase in 14-day average ambient PM₁₀ exposure was associated with lower H3K27me3 (β=-1.1%, 95% CI: -1.6, -0.6) and H3K36me3 levels (β=-0.8%, 95% CI: -1.4, -0.1). Occupation-stratified analyses showed associations between BC and both H3K9ac and H3K36me3 that were stronger in office workers (β=4.6%, 95% CI: 0.9, 8.4; and β=4.1%, 95% CI: 1.3; 7.0 respectively) than in truck drivers (β=0.1%, 95% CI: -1.3, 1.5; and β=0.9%, 95% CI: -0.9, 2.7, respectively; both p_interaction <0.05). Sex-stratified analyses showed associations between examination-day PM₁₀ and H3K9ac, and between BC and H3K9me3, were stronger in women (β=10.7%, 95% CI: 5.4, 16.2; and β=7.5%, 95% CI: 1.2, 14.2, respectively) than in men (β=1.4%, 95% CI: -0.9, 3.7; and β=0.9%, 95% CI: -0.9, 2.7, respectively; both p_interaction <0.05). We observed no associations between personal PM_2.5 or elemental components and histone modifications.

CONCLUSIONS

Our results suggest a possible role of global histone H3 modifications in effects of traffic-derived PM exposures, particularly BC exposure. Future studies should assess the roles of these modifications in human diseases and as potential mediators of air pollution-induced disease, in particular BC exposure.

Advances in Understanding Air Pollution and CVD

The MESA Air (Multi-Ethnic Study of Atherosclerosis and Air Pollution) leveraged the platform of the MESA cohort into a prospective longitudinal study of relationships between air pollution and cardiovascular health. MESA Air researchers developed fine-scale, state-of-the-art air pollution exposure models for the MESA Air communities, creating individual exposure estimates for each participant. These models combine cohort-specific exposure monitoring, existing monitoring systems, and an extensive database of geographic and meteorological information. Together with extensive phenotyping in MESA-and adding participants and health measurements to the cohort-MESA Air investigated environmental exposures on a wide range of outcomes. Advances by the MESA Air team included not only a new approach to exposure modeling, but also biostatistical advances in addressing exposure measurement error and temporal confounding. The MESA Air study advanced our understanding of the impact of air pollutants on cardiovascular disease and provided a research platform for advances in environmental epidemiology.

Exposure to air pollution as a potential contributor to cognitive function, cognitive decline, brain imaging, and dementia: A systematic review of epidemiologic research

BACKGROUND

Dementia is a devastating condition typically preceded by a long prodromal phase characterized by accumulation of neuropathology and accelerated cognitive decline. A growing number of epidemiologic studies have explored the relation between air pollution exposure and dementia-related outcomes.

METHODS

We undertook a systematic review, including quality assessment, to interpret the collective findings and describe methodological challenges that may limit study validity. Articles, which were identified according to a registered protocol, had to quantify the association of an air pollution exposure with cognitive function, cognitive decline, a dementia-related neuroimaging feature, or dementia.

RESULTS

We identified 18 eligible published articles. The quality of most studies was adequate to exemplary. Almost all reported an adverse association between at least one pollutant and one dementia-related outcome. However, relatively few studies considered outcomes that provide the strongest evidence for a causal effect, such as within-person cognitive or pathologic changes. Reassuringly, differential selection would likely bias toward a protective association in most studies, making it unlikely to account for observed adverse associations. Likewise, using a formal sensitivity analysis, we found that unmeasured confounding is also unlikely to explain reported adverse associations.

DISCUSSION

We also identified several common challenges. First, most studies of incident dementia identified cases from health system records. As dementia in the community is underdiagnosed, this could generate either non-differential or differential misclassification bias. Second, almost all studies used recent air pollution exposures as surrogate measures of long-term exposure. Although this approach may be reasonable if the measured and etiologic exposure windows are separated by a few years, its validity is unknown over longer intervals. Third, comparing the magnitude of associations may not clearly pinpoint which, if any, pollutants are the probable causal agents, because the degree of exposure misclassification differs across pollutants. The epidemiologic evidence, alongside evidence from other lines of research, provides support for a relation of air pollution exposure to dementia. Future studies with improved design, analysis and reporting would fill key evidentiary gaps and provide a solid foundation for recommendations and possible interventions.