According to recent analysis of a Delhi-based non-profit, Centre for Science and Environment(CSE), the North Indian cities see spike in winter pollution than the average of South Indian cities. Centre for Science and Environment(CSE) extensively analysed real-time and data from 99 cities to shed light on the winter air of 2019 and 2020.
According to the report, the most polluted cities this winter were located in Delhi-NCR, Uttar Pradesh, with Ghaziabad and Bulandshahar topping the list. The cities with the worst pollution rise includes Lucknow, Gurugram, Jaipur, Vishakapatnam, Agra, Navi Mumbai and Jodhpur, while Kolkata is the only megacity in this group. The cities that have met the national 24- hour standard (60 μg/m3) during the winter season are Santa, Mysuru, Vijayapura and Chikkamagaluru.

Out of 99 cities, only 19 showed substantial improvement in PM 2.5 levels, one of these was Chennai. In fact, Mysuru in Karnataka and Santa and Maiha in Madhya Pradesh are the cleanest cities in the country. However, Delhi experienced an increase in the seasonal average but a decline in the seasonal peak. It is important to note that, apart from the megacities, it is the smaller and the emerging cities that are becoming pollution hotspots.
The report said that the levels of PM 2.5 worsened in 43 out of 99 cities. PM 2.5 refers to fine Particulate Matter (smaller than 2.5 micrometers in diameter) that floats in the air, exposure to it is harmful to health, than any other pollutant. The particles are so minute that they cannot be seen through naked eyes. PM 2.5 and PM 10 are harmful as they can enter our lungs easily and cause severe respiratory problems.
Anumita Rouchowdhury, CSE’S Executive Director in charge of research and advocacy, said, “The northern Indo-Gangetic Plain is the most affected, as other regions also experience a rise, but with lesser intensity. However, the average level of PM2.5 during summer and monsoon in 2020 was considerably lower than the previous year due to lockdown, but the winter PM2.5 concentration has risen compared with 2019 in many cities.”
But the question is, why does air quality deteriorate during winter?
During winter, the level of PM2.5 is high. Polluting activities such as burning of biomass to warm up homes, burning stubble at the end of the harvest season, increase in the number of brick kilns are the major reason for high level of PM2.5 in winter. In addition to these, during winter the air near the atmosphere gets denser and cooler in contrast to normal condition in which warmer air mass is over lane by cooler air mass. The cool air trapped by warm air creates a kind of atmospheric lid known as inversion. Other factors such as vehicular and industrial emission led to rise in winter pollution.

The experts call for reforms and action in sectors such as industrial, power plants and waste management to control the rise in winter pollution and bend the annual pollution curve. Other measures to mitigate air pollution are-
1) Creating public awareness about the ill-effects of air pollution.
2) Making stringent vehicle emissions’ norms.
3) Improvement in traffic management.
4) Reducing road dust by changing road infrastructure.
5) Proper implementation of government initiatives to combat pollution.