Air quality in the national capital region was in the severe category on Tuesday morning. The air quality index, AQI was recorded 414 at 10 AM. On Monday, the air quality was in the ‘very poor’ category.
An AQI between Zero to 50 is considered ‘good’, 201 to 300 ‘poor’, 301 to 400 ‘very poor’ and 401 to 500 ‘severe’. Above 500 falls in the ‘severe plus’ category.
With the onset of winter, a dip in the minimum temperature is making the air cold and heavy leading to accumulation of pollutants close to the ground.
The government’s air quality monitor, System of Air Quality and Weather Forecasting and Research (SAFAR), said pollution levels in Delhi-NCR (National Capital Region) are expected to enter the ‘severe plus’ or ’emergency’ category on Wednesday.
Meteorologists said the national capital recorded on Tuesday morning a minimum temperature of 11.7 degrees Celsius, the season’s lowest so far. It is two notches below normal for this time of the year.
A dip in wind speed and temperature makes the air cold and denser, leading to accumulation of pollutants, said Kuldeep Srivastava, head of the India Meteorological Department’s regional weather forecasting centre.
According to the Central Pollution Control Bureau (CPCB), Delhi’s overall air quality index (AQI) read 425 at 4 pm on Tuesday. It was 360 at 4 pm on Monday.
The levels of PM 2.5 — tiny particulate matter less than 2.5 microns in diameter that can enter deep into the lungs and even the bloodstream — shot up to 292 micrograms per cubic metre, around five times the safe limit of 0-60 micrograms per cubic metre.
The levels of PM10 increased to 436 micrograms per cubic metre, more than four times the safe limit of 100 micrograms per cubic metre. Most of the 37 air quality monitoring stations across Delhi recorded air quality in the severe category.