Delhi's air improves, but still 'poor'

Delhi's air quality improved on Wednesday morning on the back of favourable wind speed but it remained poor.

The Air Quality Index (AQI) stood at 262 at 6 am, improving from 303 at 4 pm on Tuesday. It was 312 at 4 pm on Monday, the day of Diwali.

The neighbouring cities of Ghaziabad (262), Noida (246), Greater Noida (196), Gurugram (242) and Faridabad (243) reported "moderate" to "poor" air quality.

An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".

Delhi's particulate matter (PM) 2.5 pollution levels on Wednesday morning were three to four times above the national standard of 60 microgram per cubic metre for 24 hours.

The capital had recorded "very poor" air quality on Tuesday after residents in many parts of the capital flouted the ban on firecrackers on Diwali night, but the pollution levels for the next day were the lowest since 2015, thanks to warm and windier conditions that diluted its effect.

In the last two years, Delhi and its neighbouring areas had witnessed severe air quality post Diwali, which was celebrated in November, with intense smog enveloping the region for days as stubble burning peaks during the month while low temperatures and calm winds trap pollutants.

Since Diwali was observed early in the season this year, moderately warm and windier conditions prevented the rapid accumulation of pollutants from firecrackers and reduced the effect of stubble burning.

The 24-hour average AQI at 4 pm on Tuesday stood at 303, the lowest for the day after Diwali since 2015, when the Central Pollution Control Board started maintaining air quality data.

Delhi's AQI on the day after Diwali stood at 360 in 2015, 445 in 2016, 403 in 2017, 390 in 2018, 368 in 2019, 435 in 2020 and 462 in 2021.

According to the Delhi Pollution Control Committee, the capital registered a 64 per cent reduction in PM2.5 concentration and a 57 per cent drop in PM10 levels on Diwali this year as compared to last year.

It attributed the relatively better air quality this time to the reduction in stubble burning incidents in Punjab, better meteorological conditions and "less bursting of firecrackers".

The day after Diwali has seen the cleanest air this year in Delhi since 2015, but the national capital's air quality is still in the "poor" category, and the pollutants present in it can have deleterious health effects, especially for children.

Exposure to particulate matter like PM2.5 can make the children feel uneasy and even cause the problems in breathing, said Dr Jugal Kishore, Director, Professor and Head of Department of Community Medicine at Safdarjung Hospital, adding that the respiratory systems of children with allergies or asthma becomes sensitive to the particulate matter.

PM2.5 is even smaller in diameter than hair and can be inhaled into the respiratory system, travel through the airways, and eventually be transferred into the bloodstream. The effects of these chemicals on the body are numerous including a decrease in the amount of antioxidants within the body, thereby resulting in respiratory inflammation in the elderly and young children, he said.