Air Pollution

BackgroundThe relationship between prenatal exposure to low-level air pollution and child autism spectrum disorder (ASD) is unclear.ObjectiveTo examine associations of prenatal air pollution exposure with autism.MethodsWe analyzed data from 8,035 mother-child pairs from 44 United States cohorts in the Environmental influences on Child Health Outcomes (ECHO) Cohort. Fine particulate matter (PM2.5), nitrogen dioxide (NO2), and 8-h-max ozone (O3) levels were estimated at residential addresses during pregnancy. Parents rated children's autism-related traits using the Social Responsiveness Scale (SRS) (mean age 9.4 years, SD = 3.6) and reported physician-diagnosed ASD. We examined associations of the three air pollutants with SRS scores (10th, 50th, and 90th quantiles) using quantile regression and with ASD diagnosis using logistic regression. Models were run within census divisions, and coefficients were pooled in a meta-analysis.ResultsAverage (SD) pregnancy exposures were 9.3 μg/m3 (2.7) for PM2.5, 21.8 ppb (8.8) for NO2, and 40.3 ppb (5.5) for O3, with variations across census divisions. The median SRS T-score was 46 (IQR = 41 to 52), and 444 children (5.5%) had an ASD diagnosis. Higher PM2.5 was associated with higher SRS scores at the 10th quantile (β = 0.74, 95% CI: 0.09, 1.40) but not at the median or highest quantile. The association between PM2.5 and ASD diagnosis was highly heterogeneous, with associations present in the South Central, Mountain, and Pacific census divisions. Heterogeneity was also high in the association between NO2 and SRS at the median and only in the mid-Atlantic, West North Central, and South Atlantic census divisions. Higher O3 was associated with higher SRS scores at the median (β per IQR increment = 0.83, 95% CI: 0.05, 1.61) and highest quantile (β = 2.19, 95% CI: 0.06, 4.32) in the meta-analysis. Higher O3 also was associated with ASD.DiscussionAssociations with ASD outcomes were present even at low levels of air pollutants.

Ambient air pollution has been linked to elevated blood pressure (BP) in adults, but research is limited among children, particularly in sub-Saharan Africa (SSA). We investigated the potential effects of ambient fine particulate matter (PM2.5), black carbon (BC), and nitrogen dioxide (NO2) exposures on BP in school-aged children in Accra, Ghana's capital and one of the fastest growing cities in SSA. We performed a cross-sectional analysis among 919 (60% girls) schoolchildren aged 7-14 years across 90 elementary schools. Following NIH guideline, we define elevated BP as age, sex, and height specific systolic and/or diastolic BP values at ≥ 90th percentile. PM2.5, BC, and NO2 concentrations at homes and schools were estimated using spatiotemporal land-use regression models developed specifically for Accra using measurement data from 146 sites. Covariate-adjusted associations were estimated using multivariable mixed-effects linear and logistic regression models. The mean SBP and DBP among the children were 107.2 (9.7) and 69.1 (7.1) mmHg, respectively, with one-third of the children having elevated BP. Children's PM2.5 exposure at both home and school were 5-8 times the World Health Organization (WHO) annual guideline of 5 µg/m3, BC levels were above the maximum value in the "good practice statement for BC" (5.1 µg/m3), and NO2 concentrations exceeded the WHO annual guideline of 10 µg/m3 by 11-fold at some locations. Overall, PM2.5, BC, and NO2 were negatively associated with BP after adjustment for demographic and lifestyle covariates. For instance, a 10 unit increase in air pollution at homes was associated with a small decrease in SBP (PM2.5: -0.70 mmHg (95% CI -3.34, 1.94), BC: -4.61 mmHg (95% CI -9.59, 0.37), NO2: -0.19 mmHg (95% CI -0.60, 0.22) and DBP (PM2.5: -0.83 mmHg (95% CI -2.93, 1.28), BC: -4.35 mmHg (95% CI -8.19, -0.50), NO2: -0.14 mmHg (95% CI -0.46, 0.18)). Furthermore, home-level PM2.5 was associated with reduced odds of having elevated BP (OR 0.75 (95% CI 0.39, 1.41)), as was BC (OR 0.35 (95% CI 0.09, 1.39)). This study showed no evidence of pro-hypertensive effect of exposure to PM2.5, BC, and NO2 pollution among schoolchildren in Accra.

Mitigating ozone pollution remains a pressing challenge for megacities worldwide. Biogenic volatile organic compounds (VOCs) are proposed as pivotal precursors to urban ozone formation. However, direct observational evidence is scarce and the extent of this effect across cities is unclear. Here, by combining an unprecedented eddy covariance flux dataset from Beijing with modeling analysis, we find that urban vegetation contributes over half of organic reactivity essential for ozone production, predominantly driving ozone exceedances during hot periods. The unexpectedly high biogenic influences are attributed to the abundance of urban trees with strong emission potentials of VOCs within the city. Model extrapolations reveal that similar or even greater challenges exist for other cities across Asia and Oceania, where urban greening strategies often favor highly emitting trees. Our findings underscore the critical need for selective urban planning in greening programs to counteract a warming climate.

As a major component of air pollution, ambient particulate matter pollution has rarely been studied with respect to its global stroke burden. This study aims to evaluate the global stroke incidence, mortality, and health inequalities related to ambient particulate matter pollution from 1990 to 2021. Utilizing the Global Burden of Disease Study 2021, we analyzed global stroke-related mortality, disability-adjusted life years, and their age-standardized rates. The estimated annual percentage change was calculated using a linear regression model. Health inequalities were measured using the concentration index and slope index of inequality. Between 1990 and 2021, global ambient particulate matter pollution-related stroke deaths and disability-adjusted life years increased by 107% and 101% respectively, yet age-standardized rates declined. China experienced the largest increases in deaths and disability-adjusted life years, Vietnam had the fastest rise in age-standardized mortality rates, the Russian Federation saw the steepest declines in deaths and disability-adjusted life years, and Estonia had the most rapid drop in age-standardized mortality rate. Middle socio-demographic index locations accounted for 46% of the global stroke burden, with age-standardized mortality rates and age-standardized disability-adjusted life years surpassing those in high socio-demographic index locations. From 1990 to 2021, age-standardized disability-adjusted life years rose in low-middle socio-demographic index locations but fell in high socio-demographic index locations. While the concentration index signaled an improvement in global inequality, the slope index of inequality in 2021 worsened compared with that in 1990. Between 1990 and 2021, the global burden of ambient particulate matter pollution-related stroke declined. However, substantial disparities persisted across different regions, sexes, and nations. For ongoing and future research efforts, priority should be given to high-risk populations and regions, while also developing innovative interventions to further reduce the incidence of ambient particulate matter pollution-related stroke and enhance patient outcomes.