NO2 exposure and lung function decline in a cohort of adults in Mysore, India

Abstract

Abstract Increasing air pollution in low- and middle-income countries (LMICs) may be contributing to worsening respiratory health, yet to date most relevant studies have been conducted in industrialized nations. Particularly, there are few studies for India, the world’s second most populated country, and on this country’s poorest populations, who may be at the highest risk. We investigated the influence of long-term nitrogen dioxide (NO2) exposure at residential location on lung function decline over a 5-year period in a cohort of low-income adults in Mysore, Karnataka, India. In 2012–2014 and in 2017–2018, we conducted standardized interviews and performed in-home field spirometry before and after bronchodilation. We estimated annual average NO2 in 2017 based on interpolation of seasonal air pollution sampling and used linear mixed effects models with a person-specific random effect to estimate NO2 versus lung function cross-sectionally at baseline and longitudinally, adjusting for potential confounders (age at baseline, sex, smoking status, and long-term seasonality). Among healthy participants (with no COPD or asthma based on lung function tests), NO2 levels were associated with a decline in lung function pre- and post-bronchodilation (−21.7 ml [95% CI: −42.1, −1.3] for FEV1 and −22.2 ml [95% CI: −46.8, 2.3] for FVC pre-bronchodilation, −25.2 ml [95% CI: −48.4, −4.1] for FEV1 and −26.6 ml [95% CI: −51.1, −2.2] for FVC post-bronchodilation) per interquartile range (10 ppb) increase in NO2. Longitudinal impacts of air pollution on lung function were not statistically significant. Results suggest that air pollution exposure is associated with worse lung function among apparently healthy individuals among urban poor communities in India. Future studies should further characterize time-varying air pollution exposures and collect further longitudinal health data in these understudied communities.