Study finds El Niño reshaped India's winter PM2.5 pollution pattern

Key facts

• A study titled 'Air quality in flux: The baffling ENSO transition in India', published in the journal Atmospheric Pollution Research in October 2026, found that La Niña and El Niño conditions altered atmospheric circulation, PM2.5 transport pathways and weather conditions across India.
• During the La Niña winter of 2022-23, PM2.5 levels in north India fell by up to 30% from the 2019-22 average, while Mumbai's average PM2.5 spiked by about 45%.
• In the El Niño winter of 2023-24, the pattern reversed, with PM2.5 rising in north India and falling sharply in peninsular India.
• During La Niña 2022-23, stronger winds dispersed stubble-burning and local emissions, transporting pollutants southwards and raising PM2.5 in cities such as Mumbai and Thiruvananthapuram.
• Under El Niño 2023-24, weaker winds over northern India caused stagnation, with Jaipur recording about a 50% increase in PM2.5 and Delhi over a 10% spike compared with the 2019-22 average.
• In Jaipur, rainfall was more strongly linked to lower PM2.5 during 2022-23, while surface pressure became more important during 2023-24, causing pollution spikes after rain.
• Backward air-mass trajectory analysis showed Jaipur received air from polluted northern regions during the El Niño winter, while Hyderabad received more marine and southern air.
• The study found PM2.5 variations ranging from about a 40% decline to a 70% increase from 2019-22 average levels despite no major changes in emissions or pollution-control policies.
• Study author and atmospheric scientist Gufran Beig cautioned that the two studied years were unusual and not predictive of future winters, though this year's El Niño is likely to be the strongest on record.