Visibility dips as Delhi air quality in ‘severe’ zone again, 15 flights diverted
Delhi’s AQI touched 402 at around 8.30am on Friday. This is the third time in January that the pollution level has breached ‘severe’ category.delhi Updated: Jan 19, 2018 21:29 IST
Delhi’s air quality breached ‘severe’ mark once again on Friday morning as levels of particulate matter shot up because of low wind speed and high moisture. The capital also saw thick fog in the morning that affected flight schedule. By 10.30am, 25 flights had been cancelled and over 150 were delayed.
The Air Quality Index (AQI) — a measure of pollutants in the air — touched 402 at around 8.30am. On the AQI scale of scale of 0 – 500, a value between 300 and 400 indicates very poor pollution and levels beyond 400 indicate ‘severe’ pollution.
This is the third time in January 2018 that pollution level entered the severe category. While in January 2017 there was not a single day in which air pollution was ‘severe’, in January 2016 Delhi faced seven such days.
According to the Central Pollution Control Board data, the level of both PM10 and PM2.5 — the two dominant pollutants in Delhi’s air — have shot up close to emergency levels.
The concentration of PM10 was 473ug/m3 at 8am on Friday, which is close to the emergency level of 500. The concentration of ultrafine particles PM2.5 was at 273ug/m3, which is also close to the emergency mark of 300.
According to the Graded Response Action Plan emergency measures — such as shutting down of schools, ban on construction activities and odd-even road rationing — should be rolled out if the air quality remains in the severe zone for at least 48 hours.
“Low wind speed and high moisture levels are to be blamed for this. While moisture is responsible for trapping the pollutants that are being locally emitted, the low velocity winds cannot disperse them. Pollutants are accumulating in the air as a result of which air quality is deteriorating,” said D Saha head of the air quality laboratory of CPCB.
This also resulted in dense fog in the national capital. While visibility at Safdarjung dropped to around 200m at 8.30am, at Palam it was less than 50m.
The minimum temperature was at 7.4 degrees Celsius on Friday. On Thursday, Met officials said a western disturbance is approaching and that could trigger rain and thunderstorm on Tuesday.
“The rain could bring down the mercury by a few degrees. If the disturbance results in snowfall in the hills then there are chances that the chill could return,” a senior Met official said.
(With PTI inputs)