Delhi air a shade better, but emergency measures to stay

Showing marked improvement, air quality in the national capital was recorded as 'very poor' today, but the EPCA is not planning to lift the emergency measures such as ban on trucks and construction immediately.
The 24-hour average air quality index (AQI) of the Central Pollution Control Board (CPCB) was 308, which falls in the 'very poor' category, following a week-long smog episode when pollutants shot up to emergency levels.
The air quality may further improve tomorrow as light rains are expected, which will help in flushing suspended particulates away, Central Pollution Control Board (CPCB) member secretary A Sudhakar said.
According to CPCB and SAFAR scientists, the improvement has got much to do with the rise in mixing height (where air and suspended particulates mix), surface wind gaining speed, which aided rapid dispersion of pollutants, and measures implemented under the Graded Response Action Plan (GRAP).

"We are not relaxing anything as of now. The CPCB task force will meet tomorrow and the day after and suggest future course of action as drizzle is expected. Sudden relaxation and re-imposition becomes troublesome for enforcing authorities. So we will take further decisions only when the prevailing trend of improvement persists," Sudhakar told PTI.
The hourly-graph of the Central Control Room for Air Quality Management, which tracks the levels of PM2.5 and PM10, also reflected the improvement.

At 5 pm, PM2.5 and PM10 were at 259.8 and 389.2 micrograms per cubic metre respectively. Pollution is considered severe plus or emergency when these readings are above 300 and 500 respectively.

The corresponding 24-hour safe standards are 60 and 100.
A 'very poor' AQI comes with the warning that people may develop respiratory illness on prolonged exposure while exposure to 'severe' air affects healthy people and seriously impacts those with existing respiratory or cardiovascular diseases.
Currently, the severe plus measures of the GRAP, namely the ban on construction across the NCR and ban on all trucks (other than those carrying essential commodities) are in force.
According to the EPCA, these will remain imposed until air quality levels see improvement for at least 48 hours.