Ozone, PM10 key contributors to Delhi’s pollution this month

New Delhi: Ozone and PM10 have become lead pollutants in Delhi in the past few days. Central Pollution Control Board’s data shows that the prominent pollutant of the city on most days in April is not PM2.5.

The overall air quality of the capital was in ‘moderate’ category on Tuesday, but it is expected to deteriorate to ‘poor’ category on Wednesday.

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On Tuesday, the lead pollutant of Delhi’s air quality was ozone, according to CPCB’s bulletin. Ground-level ambient ozone is produced from complex interaction between nitrogen oxides and volatile organic compounds (VOCs) that are emitted from vehicles, power plants, factories, and other combustion sources and undergo cyclic reactions in the presence of sunlight to generate ground-level ozone, stated a study by Centre for Science and Environment last year. However, VOCs can also be emitted from natural sources, such as plants.

Gufran Beig, founder project director, System of Air Quality and Weather Forecasting And Research, the forecasting body under the union ministry of earth sciences, said, “In summer, temperature soars and wind blows faster. The major source of emission in summer becomes wind-blown dust. Hence, PM10 remains the lead pollutant mostly.”

He added, “If the temperature goes beyond 40 degrees Celsius, production of ozone accelerates and often ozone becomes the lead pollutant. The tiny particles, PM2.5, due to their light weight are blown away and go up or flushed away horizontally.”

According to the portal on real-time source apportionment, the share of soil and road dust in Delhi’s air quality was the highest at 29% on Monday. The real-time source apportionment project was started by Delhi Pollution Control Committee in collaboration with IIT Kanpur.

The air quality early warning system for Delhi said the air quality, which remained in ‘moderate’ category on Tuesday, is likely to deteriorate to ‘poor’ category on Wednesday and Thursday.