Pollution soars in many cities, but Delhi breathes a little better than last year

NEW DELHI: Air quality deteriorated after Diwali fireworks in many cities including Delhi, Kolkata, Chennai and Hyderabad, but favourable weather and muted use of crackers made the morning-after easier on the lungs, particularly in the National Capital Region, which was certainly polluted but not as alarmingly as last year.

The good news for Delhi is that carbon monoxide and nitrogen dioxide were at safe levels after Diwali, while ozone was at moderate levels. However, small particles suspended in the air (PM2.5) and larger particulate matter (PM10) were at ‘severe’ to ‘very severe’ levels.

The Air Quality Index (AQI), a measure of extent of pollution, rose to the dangerous level of 500 points around midnight in parts of many cities, including the large metropolitan cities as well as Jaipur, Ahmedabad and Lucknow, although the 24-hour average was between 250 and 400, which is also hazardous. The AQI is considered good at 50 points. If the index rises above 400, it is officially regarded as a health emergency.


Delhi’s air was better than the post-Diwali period last year because people burst fewer crackers following the Supreme Court’s order banning their sale, and better wind condition than last year.

After the 2016 Diwali, Delhi’s AQI was more than 700 as the city gasped under a dark haze created by pollution from firecrackers and smoke from the burning of crop residue in Punjab and Haryana.

To make matters worse, the wind was too feeble to blow away the pollutants, prompting many people to wear masks outdoors.

This year, similar adverse weather conditions hit Chennai, which saw a fourfold rise in pollution compared with last year. The wind was not strong enough to clear the air in the southern city. Bengaluru was better off with moderate levels of pollutants.

Mumbai is also facing adverse weather conditions because the wind is not blowing from the sea to the city, which brings clean air, but the other way.

Mumbai and Ahmedabad are forecast to improve from “poor” to “moderate” in two days, while Delhi is expected to improve from “severe” to “very poor” by Sunday. In Kolkata, intermittent rain and breeze quickly cleared the air, although some parts of the metropolis saw air quality index shoot to 500, according to official data.

The System of Air Quality and Weather Forecasting and Research (Safar), which operates under the Ministry of Earth Sciences, has observed that emissions from crackers have fallen sharply in Delhi this year. “It appears that Delhi is successful in reducing more than 50% firecracker emissions as compared to 2016,” it said.

The capital region has seen interesting trends this year, it observed. “Residential areas which are full of greenery and relatively cleaner in normal course, now started to show high pollution indicating that probably firecracker emissions are highest in these areas,” it said.

Air quality improved significantly in Delhi’s satellite town of Noida, which was the most polluted region in NCR last year. It now ranks second among the least polluted parts of the region, according to Safar.

The most polluted parts of the capital were the airport and Delhi University, while Pusa Road and Aya Nagar were relatively cleaner.