Pollution levels worse in small towns: Study

NEW DELHI: Winter smog and the accompanying severe air pollution is a problem usually associated with Delhi-NCR, but a new analysis by the Centre for Science and Environment (CSE) has found that when pollution spikes during winter, all of northern India experiences smog episodes, with otherwise cleaner, small towns matching or exceeding pollution levels reported in Delhi-NCR.

The study, released on Thursday, also found that while there are episodes of smog in November across the entire northern region, it lingers longer in DelhiNCR and Uttar Pradesh for the rest of the winter as compared to Punjab and north Haryana.

“Atmospheric changes during winter that include inversion, calm conditions, change in wind direction and a seasonal drop in ambient temperature across north India entrap pollutants. This is further tripped into the ‘severe’ category by smoke from farm fires and Diwali firecrackers during November. But air quality improves from ‘severe’ to ‘poor’ and ‘moderate’ categories in cities of Punjab and North Haryana post stubble fire season but it remains in the ‘very poor’ category in NCR and UP till February,” the analysis found.

For the study, data from 127 continuous ambient air quality monitoring stations (CAAQMS) across 56 cities was analysed as part of the air quality tracker initiative of CSE’s Urban Data Analytics Lab. Annual and seasonal trends in PM2.5 concentration were analysed from January 1, 2019, till November 30, 2021--the findings showed that while Delhi’s average PM2.5 concentration during winter was nearly 4.5 times the national safe standard of 60 micrograms per cubic metre, smaller towns such as

Agra, Vrindavan and Firozabad fared much worse. “For instance, smaller cities such as Vrindavan, Agra, and Firozabad have a comparatively lower annual average of PM2.5 than Delhi but during the early winter of 2021, their weekly average PM2.5 levels exceeded that of Delhi. While the annual average level of Delhi is 97µg/m³ and that of Agra is 78 µg/m³ -- 20% lower --the weekly average in Agra touched 282µg/ m³ and exceeded Delhi’s weekly average of 270µg/m³ by 5%,” said the analysis. Similarly, the weekly average of Vrindavan’s PM2.5 was found to be nearly 286µg/m³ and that of Firozabad 272µg/m³. However, both Noida and Ghaziabad exceeded these levels. While Noida’s weekly average PM2.5 was 292µg/m³, Ghaziabad’s was 360µg/m³.

“This analysis has shined a spotlight on [small] cities for us. This shows even smaller cities with lower annual levels record pollution levels that are as bad or even worse than Delhi,” said Anumita Roychowdhury, executive director, research and advocacy, CSE, stating action against pollution was needed across a much larger area.

Atmospheric changes during winter across north India entrap pollutants. CSE ANALYSIS