Delhi: Drop in air quality but rain, winds to improve conditions over the week
Delhi’s air quality saw a marginal deterioration on Tuesday, with at least 11 of the 36 monitoring stations in the Capital recording air quality index (AQI) in the ‘poor’ category, up from seven stations a day ago, data from the Central Pollution Control Board (CPCB) showed.
However, India Meteorological Department (IMD) scientists said that the pollution situation in the Capital will improve in the coming days with wind speeds expected to pick up from Wednesday and light to moderate rain forecast on between October 17 and 18.
CPCB data showed that on Tuesday, the overall AQI in Delhi was 179, up from the 166 on Monday, both of which are in the ‘moderate’ category.
IMD scientists said that the brief deterioration in air quality was because of calm winds. “The winds were calm on Tuesday and the primary pollutant in Delhi was PM 10 (particulate matter of diameter less than 10 micrometres) or dust from local sources. Currently, the impact of stubble fires is not much. From Wednesday, wind speeds will pick up and pollution is likely to go down,” said a senior IMD scientist.
He also said that there is a forecast of rain in Delhi and neighbouring states, which will also result in an improvement in air quality.
“Since there are not much pollutants in the air now, the rains will help clear the pollution levels. Usually, if the pollution load in the atmosphere is high, and the humidity levels also increase, pollutants stick to it and settle close to the surface,” he explained.
Mahesh Palawat, vice-president (meteorology and climate change) at Skymet Weather Services, said that the wind direction over Delhi is expected to change from October 16, and light to moderate rains are likely over Delhi-NCR between October 17 and 18.
“At present, Delhi is receiving westerly winds. From October 16, the wind direction will change to easterly, which will also result in light to moderate rains in the city. The neighbouring states will also receive moderate to heavy rains,” Palawat said.
Scientists warned that though the impact of stubble fires is low in Delhi’s air for now, pollution will start rising in the coming weeks as temperatures drop and stubble burning activities pick up.
Data collated by United States’s National Aeronautics and Space Administration (Nasa) shows that between September 1 and October 11 this year, Punjab reported 918 stubble fires, much lower than 2,996 instances reported in the same period last year. In Haryana, 442 fires were reported between September 1 and October 11 this year, as opposed to 750 reported during the same period last year.
“Last five years of satellite data for stubble burning in Punjab and Haryana clearly shows late and slow starts of the season compared to previous years, potentially due to prolonged monsoon and change in policies. We will have to monitor the numbers in the coming weeks,” said Pawan Gupta, a research scientist at the Goddard Earth Sciences Technology and Research (GESTAR), Universities Space Research Association.