As the concentration of pollutants in the capital dipped after Monday’s rainfall, experts are now worried about the impact of crop residue burning in Punjab and Haryana.
Officials at the System of Air Quality and Weather Forecasting and Research (SAFAR) said Delhi’s air, which has so far seen minimal impact of crop residue burning, will see a more heightened effect till Friday.
Rain, which lashed several parts of the city on Monday evening, however, helped lower the concentration of particulate matter, which was the primary pollutant for the past several days, said officials.
The analysis of air quality figures in the first 14 days of May in the years 2017, 2018 and 2019 shows that dust is usually the primary pollutant during this time of the year.
In 2017, the average air quality index value of the city during the period was 280. In 2018, it improved to 194, but has deteriorated to 266 this year.
Officials at the Delhi Pollution Control Committee (DPCC) said the primary reason behind the dip is the dry season.
“May usually sees bouts of light rain and squalls. This year, however, the first rain that the city saw was on Monday. In cities, dust from roadsides and construction sites is among the primary causes of pollution. These can be controlled by regular rains. With high temperatures, dust comes off loose and winds whip it up in the air. The wind system over the past week has also brought to the city a lot of dust from the western parts of the country. Sprinkling would be helpful at this time,” said a senior DPCC official.
As per data, Delhi saw three dust storms and four squalls each in May 2017 and 2018. In 2016, there was only one dust storm and eight squalls. A squall sees strong winds and is accompanied by light rain, and sometimes dust.
Squalls are more common as compared to dust storms. This year, however, there has been no squall in the first two weeks of the month. On Monday, an IMD official had said: “The whole of this week is expected to see light rain or thunderstorms. The month of May is also when these occurrences are more common because of the interaction of hot air in the area with any cooler wind system that enters it. The clash of the two systems — local and regional — leads to thunder and dust storms,” said an IMD official.