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Low ozone concentration over Guwahati compared to other urban locations in India

Scientists at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, have evaluated the near-surface ozone in the Brahmaputra River Valley and found a relatively low concentration of ozone over Guwahati compared to the other urban locations in India, a statement said on Saturday.

Their work has been published recently in the journal ‘Atmospheric Pollution Research’.

ARIES is a research institute under the Department of Science and Technology (DST).

“Scientists evaluated the near-surface ozone in the Brahmaputra River Valley (BRV) and found a relatively low concentration of ozone over Guwahati compared to the other urban locations in India,” the statement said.

Tropospheric, or ground-level ozone, is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC).

It usually increases when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight, impacting human health.

In the study led by Umesh Chandra Dumka (a scientist with ARIES) along with A S Gautam (professor at Hemvati Nandan Bahuguna Garhwal University), Suresh Tiwari (scientist Indian Institute of Tropical Meteorology) and Prof. Philip K Hopke (adjunct professor, University of Rochester School of Medicine and Dentistry, USA) and Prof R K Chakrabarty (Washington University, USA) and other team members analysed the variability of ozone and other air pollutants over the Brahmaputra river valley region.

It also assessed seasonal, day of the week, and characteristics of ozone to identify the emission source of ozone and its precursors, especially methane (CH4) and NMHCs, along with study the relationships between the meteorological parameters, ozone and its precursors in a tropical setting, the statement added.

The examination of nitric oxide, nitrogen dioxide, and ozone concentrations in this study suggested that this site is well influenced by local sources such as adjacent major national highway.

During the daylight hours, the site is in or nearly in a photo-stationary state, indicating a low impact of organic species on the ozone concentrations.