New Delhi: The three-day streak of poor air quality ended Saturday, with the AQI marginally improving to 191 in the higher end of the ‘moderate’ category. The improvement was due to a change in wind direction to easterly and an increase in wind speed. However, air quality is likely to deteriorate to ‘poor’ again Sunday.Delhi’s AQI turned poor for the first time this season on Oct 21 at 245, prompting the Commission for Air Quality Management (CAQM) to impose stage I of Graded Response Action Plan. The AQI was 223 Thursday and 230 Friday. “The change in wind direction from north-westerly to easterly reduced the transport of pollution from outside Delhi. An increase in wind speed also helped disperse pollutants, improving air quality,” said an official.However, the respite is temporary as the air quality is likely to remain in the poor category from Sunday to Tuesday.The AQI was 185 at 9 am but deteriorated to 191 at 4 pm, as per Central Pollution Control Board’s (CPCB) 24-hour average bulletin. At 8 pm, it was 188.Dipankar Saha, former head of the CPCB’s air laboratory, said air quality typically deteriorates during the post-monsoon season due to stagnant conditions and changes in wind direction. “The atmosphere’s capacity to disperse and dilute pollutants decreases compared with summer and the monsoon season. The transport of emissions from upwind regions further adds to the pollution load in Delhi and its surrounding areas. As a result, air quality tends to worsen during winter period,” he said.This Oct so far has recorded three poor days, 19 moderate days and two satisfactory days. In Oct last year, Delhi reported 11 poor days and seven very poor days.Meanwhile, the maximum temperature Saturday was 32.9 degrees Celsius, one degree above normal. The minimum temperature was reported at 18.3 degrees Celsius, one degree above normal.
