CSE finds ground-level ozone pollution in Delhi-NCR all-year problem, persists at nights too

Source: The post is based on the article “CSE finds ground-level ozone pollution in Delhi-NCR all-year problem, persists at nights too” published in the DTE on 5th June 2023

What is the News?

According to the Centre for Science and Environment’s (CSE) analysis, the ground-level ozone pollution affecting parts of the Delhi-National Capital Region (NCR) was lower this year than in the last five years, but the duration of its exceedance was higher.

The report was based on data from the Central Pollution Control Board (CPCB). The analysis highlights the duration and geographical spread of Ozone Pollution, its impact during different seasons, and the underlying causes.

What is ground-level ozone and its impact on health?

Ground-level ozone is a colourless and highly irritating gas that forms near the Earth’s surface, typically within two miles above the ground. It is also known as Tropospheric ozone.

The WHO Air Quality Guidelines for ambient (outdoor) ozone is 100 μg/m3 (~50 ppb) measured as an 8-hour maximum moving average within a day.

What are the key findings of the CSE analysis on ground-level ozone pollution?

Exceed in duration: Many parts of the Delhi-NCR region witnessed ground-level ozone exceeding the national standards on 87 out of 92 days between March and May in 2023. Elevated ozone levels persist even hours after sunset in NCR, this is contrary to expectations.

Not limited to seasons: Ozone pollution is not limited to specific seasons. Even during winter months, Delhi-NCR experienced excess ozone levels on multiple days in January 2023.

High vulnerable areas: New Delhi and South Delhi areas were the most affected by ground-level ozone pollution.

Note: In winter months cold and foggy conditions inhibit ground-level ozone formation.