Why ozone prominent pollutant over past two days in Delhi

Last Updated09/05/2023

Ozone has once again been identified as a prominent air pollutant in Delhi when AQI was in the ‘moderate’ category.
At some air quality monitoring stations, ozone levels have crossed the hourly standard of 180 µg/m3 set by National Ambient Air Quality Standards, while it remained within standards at others.

Ozone (O3) high in the Earth's atmosphere protects us from the sun's harmful radiation.
But ozone at ground level (tropospheric ozone), is an air pollutant that harms people and plants.
Ground-level ozone is a colourless and highly irritating gas that forms just above the earth's surface.

It is called a "secondary" pollutant because it is produced when two primary pollutants react in sunlight and stagnant air.
These two primary pollutants are nitrogen oxides (NOx) and volatile organic compounds (VOCs).
These precursor primary pollutants are each produced primarily by a variety of human activities, including burning of fossil fuels and various industrial processes. Certain types of volatile organic compounds can also be emitted from natural sources.

Ground-level ozone is known to have significant effects on human health.
Exposure to ozone has been linked to premature mortality and a range of morbidity health issues.
It can significantly impact vegetation and decrease the productivity of some crops.
It can also damage synthetic materials, cause cracks in rubber, accelerate fading of dyes, and speed deterioration of some paints and coatings.