The association of asthma and air pollution: Evidence from India

Association of short-term exposure to PM2.5 and its components with hospital admission for asthma in Shanghai: a time-stratified case-crossover study

INTRODUCTION

Associations between PM2.5 and the risk of asthma admission have been established in previous researches. However, evidence about the specific impacts of PM2.5 components on asthma-related hospitalizations across different populations and environments is limited and inconsistent. The purpose of this study was to examine the association between short-term exposure PM2.5 and its components with asthma hospital admission.

METHOD

A total of 930 people hospitalized for asthma were included in the study in Shanghai between December 2018 and December 2022. Air pollution data were assigned to individuals based on their residential address using the Tracking Air Pollution (TAP) platform. A time-stratified case-crossover design and a conditional logistic regression model were used to estimate the risk of asthma admissions related to exposure to PM2.5. We also conducted stratified analyzes by age, gender, and season.

RESULTS

Each 10 μg/m³ increase in PM2.5, BC, NO3-, NH4+, SO42- and OM at lag-5 day were associated with increased risk of asthma admission, with ORs of 1.04(1.00,1.08), 2.59(0.99,6.76), 1.17(1.02,1.33), 1.33(1.06,1.66), 1.28(1.05,1.55) and 1.16(0.98,1.37), respectively. Stratified analysis showed that PM2.5 and its components had a more significant impact on the risk of asthma admission for women; individuals aged ≥ 65 years, and during cold seasons at lag-5 day. The results remained stable in the sensitivity analysis.

CONCLUSION

Short-term exposure to PM2.5 and its components (NO3-, NH4+, SO42-) increases hospitalization risk in asthma patients, particularly among women, elder and those admitted during cold seasons. It provides new insight for reducing the asthma burden associated with particulate air pollution.

Long-term exposure to ambient PM2.5 and population health: evidence from linked census data

Particulate matter suspended in the air that is comprised of microscopic particles with a diameter of 2.5μm or less (PM2.5) is among the most impactful pollutants globally. Extensive evidence shows exposure to ambient PM2.5 is associated with a wide range of poor health outcomes. However, few studies examine long-run pollution exposures in nationally representative data. This study exploits Census data for Northern Ireland, linked to average PM2.5 concentrations at the 1x1km grid-square level during the period 2002-2010. We combine outcome measures in 2011 with data on complete residential histories. Before adjusting for other covariates, we show strong relationships between PM2.5 exposure, self-rated general health, disability, and all available (eleven) domain-specific health measures in the data. Associations with poor general health, chronic illness, breathing difficulties, mobility difficulties, and deafness are robust to extensive conditioning and to further analysis designed to examine sensitivity to unobserved confounders.

Examining the impact of air pollution, climate change, and social determinants of health on asthma and environmental justice

PURPOSE OF REVIEW

In this review, we discuss the current literature examining the impact air pollution and climate change has on asthma onset, control, and exacerbation. This review also addresses the risk of exposure to specific disproportionately affected communities, highlighting health disparities in exposure and asthma outcomes.

RECENT FINDINGS

Recent studies have shifted from highlighting the associations between asthma exacerbations and indoor and outdoor air pollution. Studies are now focused on confirming the association of asthma incidence from these same exposures. Many studies have linked particulate matter to adverse asthma outcomes, however, the pollutant exposures that pose the greatest risk and the effect of natural disasters fueled by climate change are under current study. Some studies have observed that the true burden that pollutant exposures have on asthma outcomes occurs at the intersection of exposure and vulnerability. Future studies in this area will address social determinants of health, societal factors such as redlining and other systemic racism practices.

SUMMARY

Although decades of research support the causal link between gaseous and particulate air pollution and the exacerbation of preexisting asthma, recent studies suggest air pollution can cause incident (new onset) asthma. Studies have started to focus on the underlying drivers of poor outcomes in asthma. Many of the structural impediments to high quality asthma care at the society level (e.g. poverty, redlining, systemic racism) also are risk factors for worsened climate events and air pollution exposure. The individuals in these disproportionately affected groups are doubly affected by worsened exposure and worsened access to care for the resultant asthma exacerbations or incident asthma. More research is needed to understand the specific climate and air pollution mitigation efforts where disproportionately affected communities would derive the most benefit.