Delhi air ‘very poor’ on Wednesday, may get better on Thursday

According to MeT officials, the concentration of pollutants fell slightly because of good wind speed during the day.

Delhi’s air quality continued to be in ‘very poor’ levels on Wednesday, despite predictions of increase in pollution. According to Met officials, good wind during the day has dispersed pollutants and prevented the air quality from getting fouler.

According to Met officials, the concentration of pollutants fell slightly because of good wind speed during the day. (Sanchit Khanna/HT PHOTO)

According to MeT officials, the concentration of pollutants fell slightly because of good wind speed during the day.

“During the daytime and evening on Wednesday, the wind speed was 10-12km/hour and thereby there was an improvement in the air quality after it worsened from Tuesday evening. On Thursday, air quality might improve a bit because of this windy condition,” Kuldeep Srivastava, a senior Met department scientist, said.

The day’s average Air Quality Index was 363, more than Tuesday’s 335, both classified as “very poor” by the CPCB. On Monday the AQI was 372, while on Sunday the reading was 305. The AQI is calculated on a scale of 0-500. An AQI between 0-50 is considered good, 51-100 satisfactory, 101-200 moderate, 201-300 poor, 301-400 very poor and 401-500 severe.

The levels of PM10 and PM2.5, however, kept fluctuating throughout the day. While PM10 showed little deviation from 357.8μg/m3 at 6am to 357.2μg/m3 at 6pm, the level of PM2.5 kept oscillating from 219.5μg/m3 at 6am to 220.3μg/m3 at 6pm.

Both PM10 and PM2.5 are ultra fine particles, the dominant pollutants in Delhi. The acceptable levels of PM10, the larger particulate matter, and PM 2.5, which measures the finer and more dangerous particulate matter, are 100μg/m3 and 60μg/m3, respectively.

The foggy conditions in the early hours will remain for the coming 3-4 days.

“On Wednesday, there was moderate fog with visibility going down to 400m. On Thursday, too, similar conditions are expected in the early hours with visibility set to be around 300-400m,” Srivastava said.

Earlier, on Tuesday, the MeT had predicted low winds, poor ventilation coefficient and stable atmospheric conditions which is likely to cause episodic severe air quality events, particularly in the evening and night till 29.12.2017. “In view of this, agencies concerned have been requested to remain alert and take all necessary measures for preventing emergency situation,” an official had said.

However, strong winds during the day have kept the air quality from worsening into “severe” levels.

On Thursday, partly cloudy sky is expected and the maximum and minimum temperatures would be around 25 and 08 degree Celsius respectively.

On Wednesday, the maximum temperature was 25.4 degree Celsius, five notches above normal, while the minimum temperature notched 7.6, one degree above what is normal this time of the year.