NEW DELHI: Air quality in the national capital plunged to the 'very poor' zone on Tuesday, for the first time this season. While at present the share of smoke from stubble burning to the overall pollution levels in the city is low, it is mainly local pollutants, dip in mercury and the festive rush behind the spike in levels, scientists and officials said. Post-Diwali the air quality is likely to worsen to the deep end of 'very poor'.
As per the Central Pollution Control Board (CPCB), the overall air quality index (AQI) on Tuesday was 303 in the lower end of the 'very poor' zone. According to the Union Ministry of Earth Sciences' (MoES) air quality and weather forecasting system, the AQI is likely to remain in the 'very poor' zone over the next two days.
"The impact of stubble burning at present is low due to southeasterly winds. However, during November 4-6, the expected share of stubble burning in the city’s overall PM2.5 levels is likely to go up ranging from 20 per cent - 38 per cent," the bulletin stated.
Officials said that while the city government has imposed a blanket ban on sale and purchase of firecrackers, these still burst on Diwali day and even after that, causing a major spike in pollution levels.
Because of delayed rains, the peak stubble burning activity in Punjab and Haryana is likely to coincide with the Diwali week, which could result in a short and severe smog episode.
A senior official from the Delhi government's environment department said that at present the wind-direction is still southeasterly and there is a forecast of a Western Disturbance, which may result in light rainfall in some parts of the region on Wednesday.
"While stubble burning instances are on a rise, it’s just that the winds are not coming from the northwest and hence the spike in pollution levels that we are seeing is mainly of localised pollution and the festive rush. However, we may move to the higher end of the 'very poor' zone by the weekend," said the official.
According to officials in the IMD, the wind direction is likely to change to northwesterly around November 4. "Air quality is likely to remain in the lower end of very poor over the next two days, but is likely to worsen from November 4 itself with a transition in wind direction. The transition itself causes calm conditions, which is not favourable for dispersion of pollutants," said RK Jenamani, senior scientist, IMD.
Bad air amid festivities
303: Very poor AQI
Last time when air quality was in 'very poor' zone this year: June 9 (305)
6 per cent: Contribution of stubble burning to PM 2.5 levels