In addition to particulate matter due to dust storms, the rising ozone levels have added to the pollution burden in Delhi-NCR.

PM2.5 and tropospheric ozone are the two indicators used to quantify exposure to outdoor, or ambient, air pollution in the GBD project as stated in the WHO report “State of Global Air 2018”.

Ozone in the upper atmosphere or stratospheric ozone is good ozone and protects from the harmful UVB rays of the sun. The thinning of this layer due to destruction by chemicals is seen as a hole, called ‘ozone hole’ through which the harmful UV rays reach the earth.

A depleted ozone layer in the stratosphere allows the ultraviolet rays of the sun to reach the earth exposing mankind, flora and fauna to its harmful effects. 

It is the ground level ozone or tropospheric oxygen, which is a harmful air pollutant and affects human health. Ground level ozone is formed when chemical reactions occur between pollutants nitrogen oxides and VOCs from industrial emissions, vehicle exhaust in sunlight.

Traffic emissions constitute more than half of the ozone precursors. Ozone along with particulate matter also forms smog.

Breathing ground level ozone can damage the lung tissue and reduce lung function of anyone and can especially worsen pre-existing respiratory conditions like bronchitis, emphysema and asthma. Children, elderly, outdoor workers are most at risk of breathing air containing ozone.

Dr KK Aggarwal

Padma Shri Awardee

Vice President CMAAO

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA