Air pollution in Punjab, India: insights and implications for air quality in the indo-gangetic plain

Utilizing data from real-time monitoring stations of the Central Pollution Control Board (CPCB), which encompass pollution activities in the region, including stubble burning and other anthropogenic sources, this study evaluates the National Air Quality Index (NAQI). The analysis examines spatial variations in seven key air pollutants—particulate matter (PM2.5 and PM10) and gaseous pollutants (NH3, NO2, O3, CO, and SO2)—across Punjab, India during three distinct phases: pre-lockdown, complete lockdown, and post-lockdown, providing insights into the shifts in air quality influenced by both natural and human-induced factors. The results showed that air quality was significantly improved during the lockdown. PM2.5, PM10, and NH3 saw the most substantial reductions (40–60%). The absolute drop in PM2.5, PM10, and NH3 was noted during peak morning traffic hours (08–10 Hrs) and late evening traffic hours (20–24 Hrs); however, the percentage reduction remained nearly consistent throughout the day. SO2 and O3 had a mixed pattern of increase and decline, with a modest increase at some sites and a considerable decrease at others. In the central region, there was a significant drop in NO2 and CO (50–60%). The decrease in PM2.5, PM10, NH3, NO2, and increase in O3 was related to population density. As a result, Punjab’s air quality has improved, with a significant drop in major pollutants; nonetheless, some regions have seen an increase in SO2 and O3. Changes in emissions, meteorology and atmospheric chemistry documented during the lockdown necessitate further examination.