Assessing the impact of forest fires on air quality in Northeast India

Abstract

This study investigates the impact of forest fires on air quality in India's northeastern (NE) region, focusing on Guwahati, Tezpur, and Aizawl. The North-Eastern Forest cluster, contributing 36% to the total forest cover, emerges as a hotspot with the highest number of fire detections (40%). Population growth and shifting cultivation practices have intensified the frequency of fires. The study spans 2013–2016, assessing PM₁₀, PM_2.5, ozone (O₃), carbon monoxide (CO) and nitrogen oxide (NO_x) concentrations in the three NE cities. Guwahati consistently recorded PM₁₀ concentrations above National Ambient Air Quality Standards (NAAQS), indicating persistent air quality challenges. Tezpur and Aizawl maintained concentrations below NAAQS, with Aizawl displaying Good to Satisfactory air quality on a significant portion of observed days. During forest fire (FF) events from 2013 to 2016, PM₁₀, PM_2.5, O₃, CO, and NO_x concentrations rose, suggesting a direct correlation between FF and deteriorating air quality, especially when FF counts were above 100. During these events, a shift in air quality levels was observed, affecting most parameters in Aizawl and varying for other cities. Diurnal patterns during FF events indicated increased pollutant levels. The most prominent change was observed in PM₁₀ in all stations. Backward air–mass trajectory analysis confirms the influence of NE-India as a significant pollution source during FF. This study underscores the urgent need for targeted interventions to mitigate the impact of FF on air quality in the NE region, emphasising the intricate relationship between ecological practices, forest fires and atmospheric conditions.