Delhi’s average AQI falls, but everyday air gets more polluted, says study | Delhi News

The city recorded the fourth poor day of the month as the air quality index (AQI) worsened to 229 Wednesday

New Delhi: Delhi’s air quality showed an apparent improvement this autumn, but a closer look at the numbers reveals a more complicated picture. The city experienced fewer extreme pollution days, while its typical day became more polluted, a new analysis reveals.The assessment by Climate Trends, a research-based initiative, compared Delhi’s air quality between Sept 15 and Oct 23 across 2024, 2025 and 2026. It found that the mean air quality index, the average of daily AQI readings across the period, fell 15.8%, from 169.3 in 2025 to 142.6 in 2026. However, the median AQI, which represents the middle reading and better reflects a typical day, rose 14.1%, from 135 to 154.The number of days with AQI above 200 dropped from 10 in 2025 to just three in 2026, while the maximum daily AQI fell from 353 to 245. Yet the median AQI rose from 135 to 154, even as the mean fell from 169.3 to 142.6. The figures suggest that Delhi experienced fewer severe pollution episodes, but its typical daily air quality did not improve.The findings also challenge the tendency to explain Delhi’s autumn pollution primarily through stubble burning in neighbouring states. Satellite-detected crop-residue fires in Punjab and Haryana fell marginally from 201 in 2025 to 193 in 2026, a decline of 4%. Yet the same-day correlation between fire activity and Delhi’s AQI weakened sharply, from 0.62 to 0.17.Weather conditions offered no straightforward explanation for the improvement. According to the analysis of NOAA’s Global Forecast System data, Delhi’s mean wind speed increased by 2.1% in 2026, potentially aiding dispersion. However, the planetary boundary layer height fell 4.3%, while accumulated precipitation declined 78.2% compared with 2025.The analysis suggests that changing emissions and atmospheric conditions may both have contributed to the lower average AQI, but it cannot establish the precise contribution of individual factors. Traffic, industry, road and construction dust, and other regional combustion sources remain important parts of the pollution picture.The findings caution against treating a lower average AQI as proof that Delhi’s air has become consistently cleaner, the analysis emphasises. Fewer severe pollution episodes are encouraging, but the rise in median AQI underlines the need to understand and address the sources affecting residents’ everyday exposure, it adds.