India, Oct. 14 -- The Capital witnessed the pre-winter season's first whiff of "poor" air quality on Tuesday as the air quality index crossed the 200-mark, barely a week ahead of Diwali, even as forecasts showed no relief in the coming week. The CAQM announced it was invoking stage 1 of the graded response action plan, or Grap, which includes stronger monitoring of open burning and the use of dust suppression measures.

Data from the Central Pollution Control Board showed that at 4 PM, the 24-hour average AQI stood at 211-the first reading in this range since June 11, when it was 245. Experts said the deterioration in air quality is due to a dip in both wind speed and night temperature.

The situation is likely to worsen around Diwali, in...