India / Air quality slips into severe zone, may get even worse in Delhi today

Reduced wind speed, dense fog and low temperature pushed the air quality in Delhi into ‘severe’ category on Friday. The overall air quality index (AQI) in Delhi was 432 on Friday, a considerable spike from Thursday’s 362, which is considered to be in the ‘very poor’ category. At 7.30pm, the air quality at several monitoring stations had already dropped to the emergency zone. The AQI at Okhla phase 2, Mundka, Pusa, Vivek Vihar, Ashok Vihar, Nehru Nagar and Jawaharlal Nehru Stadium monitoring stations had crossed the 450 mark.

The particulate matter levels also showed an upward curve throughout Friday. At 1am on Friday, the PM 2.5 (particulate matter with diameter less than 2.5 micrcometres) levels was recorded 233ug/m3. By 8pm, the levels were 273ug/m3, just a few points away from the emergency mark of 300ug/m3. The PM 10 (particulate matter with diameter less than 10 micrometres) also shot up to 402ug/m3. The emergency mark for PM 10 levels are 500ug/m3.

Scientists at the India Meteorological Department (IMD) said that from Thursday evening the winds have remained calm and the dense fog spells in the morning and night are making the situation worse. The low mixing height, which is trapping pollutants closer to the ground, and the moisture in the air are also providing the perfect conditions for the air quality to deteriorate.

A senior scientist at the IMD said that the forecast is possibility of light rain from late Friday night and Saturday, which will bring some relief for the pollution levels.

“From tomorrow (Saturday) afternoon the AQI is expected to improve. The temperature will increase tomorrow, but from Monday there will be a dip in temperature again,” the scientist said.

System of Air Quality and Weather Forecasting and Research (SAFAR), ministry of earth science’s weather and air quality forecasting centre, also said that wind speeds will remain low till Saturday afternoon, after which the rain in certain parts of Delhi-NCR will improve conditions.

“AQI is likely to deteriorate further in severe category till tomorrow (Saturday) afternoon. Decrease in minimum temperature is forecasted, conditions are favourable for dense fog formation. Increase in wind speed is forecasted and there is a possibility for scattered rain over Delhi region by tomorrow night,” the forecast read.

It added, “The improvement in Air Quality Index will depend on the strength of rainfall. It should be noted that slight drizzle can deteriorate air quality. On 22nd December wind speeds are forecasted to pick up further and AQI is likely to improve to the middle end very poor category. By 23rd December AQI is forecasted to improve to middle to lower end of very poor category.”