Breathing like a smoker: Estimating relative risk of PM2.5, BC, and NO2 exposure in semi-urban India for better public perception

Despite being a leading cause of health issues, air pollution in smaller cities is often overlooked. To address this gap, annual monitoring of Fine Particulate Matter (PM_2.5), Black Carbon (BC), and Nitrogen Dioxide (NO₂) was conducted at a residential site in a semi-urban area and, for comparison, in an urban area. The sampling site was affected by multiple, co-located sources, including the National Highway (NH-19), traffic intersections, street vendor stalls, and other commercial areas, resulting in high exposure levels. The collected data were analyzed to understand the dynamics, variations, morphology, and chemical composition of particles; these levels were then assessed concerning passive cigarette smoke (PSC) exposure, evaluating potential health impacts. Four health outcomes—cardiovascular mortality (CM), lung cancer (LC), low birth weight (LBW), and decreased lung function (DLF) in school-aged children—were assessed to quantify the burden. The results indicate that even minimal concentrations can significantly affect human health, as a rise of 10 μg/m³ in PM_2.5 and NO₂, along with 1 μg/m³ in BC, is associated with mean increases and standard errors of 8.1 (3.98), 8.5 (4.48), and 3.03 (1.22) PSC per day across the four health outcomes, respectively. Seasonally, the post-monsoon period showed predominance due to extensive use of biomass and fossil fuels for heating and cooking in semi-urban regions, leading to an elevated prevalence of decreased lung function (DLF), with 18 passive cigarettes identified as the most significant risk factor among the various outcomes. This study emphasizes the need for population-based monitoring to issue public health advisories that protect vulnerable groups, especially in smaller cities such as Tundla, located in Northern India.