Delhi’s air quality improves but still severe. On Friday morning, at around 8 am, the Air Quality Index — a measure of pollutants in the air — had come down to 418 after having shot up to 469 on Thursday.
An AQI value above 400 on a scale of 0 – 500 is interpreted as ‘severe’ pollution.
The levels of particulate matter — PM10 and PM2.5 — also saw significant improvement.
The concentration of PM10 in the air dropped to 386ug/m3 at around 8 am on Friday from around 499ug/m3 around 1 pm on Thursday. The level of PM2.5 also dropped from 321ug/m3 to 239ug/m3 around the same time. If PM10 and PM2.5 hit 500 and 300 it is considered as ‘emergency’.
“Concentration of particulate matter is now out of ‘emergency’ zone. It is likely to improve further during the day,” said D Saha head of the air quality laboratory at CPCB, the country’s apex pollution monitoring body.
s the sun came out and the winds picked up speed, visibility also showed signs of improvement. At Safdarjung, visibility improved from around 500m at 5.30am to around 700m at 8.30am. At Palam, the visibility, which had dropped to around 350m at 5.30am, improved to 400m at 8.30am.
Delhi’s air quality had plunged to ‘severe’ zone on Thursday after a gap of over a month. The last time the National Capital witnessed such foul air was on November 13.
Delhi had witnessed around six days of ‘severe’ pollution in December 2016. In December 2015, however, there were no severe days of pollution.
Emergency measures such as shutting down of schools, ban on construction activities and rolling out of odd-even road rationing are enforced if the levels of PM10 and PM2.5 stay above 500 and 300, respectively, for at least two consecutive days.>