Maha cities see rise in ozone levels during lockdown: Nat’l Clean Air Programme
Despite the decline in traffic pollution during the lockdown imposed due to the Covid-19 pandemic, 10 cities in Maharashtra are reporting an increase in urban ground-level ozone, a harmful pollutant, according to a recent study. The Mumbai Metropolitan Region (MMR), comprising Mumbai, Thane, Navi Mumbai, and Kalyan, witnessed a 24.8% spike in urban ozone during the first three phases of the lockdown over two months (March 24 to May 24), according to an analysis released as part of the National Clean Air Programme (NCAP) tracker on Tuesday by Mumbai-based air quality research group Respirer Living Sciences (RLS) and Delhi-based communications initiative, Climate Trends.
The 10 cities in the state which saw an increase in ground-level ozone are Mumbai, Navi Mumbai, Thane, Kalyan, Chandrapur, Aurangabad, Nagpur, Nashik, Pune and Solapur. The Maharashtra Pollution Control
Board (MPCB) confirmed the findings were accurate.
Surface ozone (O3) is a photochemical oxidant which is formed when volatile organic compounds and oxides of nitrogen (NOX) chemically react in the presence of heat and sunlight. Ground-level ozone is harmful to humans as it can aggravate asthma, cardiovascular diseases, and other ailments.
The latest study found a 10.3% rise in ozone across 10 Indian cities during the first two months of the lockdown. Among monitoring locations across the state,
Khadakpada in Kalyan has shown the highest average ozone levels at 70 micrograms per cubic metre (μg/m³) against the safe limit of 80μg/m³ (for 24 hours), followed by the Maharashtra Industrial Development Corporation’s Khutala station in Chandrapur at 64μg/m³. While the concentration ranged between 23-37μg/m³ for MMR, a 50% increase in average O3 levels was witnessed when compared to 2019. Comparatively, a 50% reduction for Mumbai and 58% for Thane was witnessed for nitrogen dioxide (NO2) levels.
NO2 is formed while burning of coal and vehicular exhaust.
“The analysis indicates that when NO2 levels remain low, surface ozone is higher as photochemical production can become more efficient during summer months,” said Ronak Sutaria, founder and director, RLS. “Breathing air with high ozone poses risk for people with asthma and other lung ailments, especially for children, older adults, and those active outdoors such as daily wage workers.”
MPCB said it was investigating the spike in the pollutant by comparing readings from different stations. “Based on our preliminary data collection, ozone is going up across Maharashtra cities,” said SC Kollur, chief scientist, MPCB. “It may be a secondary pollutant arising from the reduction of other major pollutants. Industrial areas do witness such spikes but the increase for major cities comes as a surprise. We have to analyse the source.” For Mumbai, MPCB plans on studying background data from the Borivli station to check reasons for an increase in ozone.