The study revealed that the concentration of nitrogen dioxide, nitrogen oxide and carbon monoxide came down during the lockdown by 33.7%, 53.8% and 27.25% respectively, as the Covid-19 lockdown and subsequent restrictions, helped Hyderabad reduce the atmospheric pollutants considerably.
Researchers carried out a comparative study on the pollutant concentrations during the pre-lockdown (February 1 to March 23, 2020) and lockdown period (March 24 to April 30, 2020) to those of the pollutants in the previous years (2018 and 2019). Carbon monoxide, nitrogen oxides and ozone were monitored along with meteorological parameters like temperature, relative humidity and solar radiation over Hyderabad to arrive at the results.
“Covid-19 lockdown improved the air quality by the reduction in air pollutants leading to increased ozone concentration,” the study said.
Besides IICT, the research team is drawn from the Academy of Scientific and Innovative Research (AcSIR), Ghaziabad. The research study by Sarat Kumar Allu, Aparna Reddy, Shailaja Srinivasan, Rama Krishna Maddala and Gangagni Rao Anupoju was published in the latest issue of science journal, ‘Environment Processes’.
According to the study, during the lockdown the concentrations of carbon monoxide, nitrogen dioxide and nitrogen oxide showed significant declining trends.
“Carbon monoxide has shown a maximum concentration of 349.68 ppb by volume during the pre-lockdown period, which decreased to a minimum of 192.5 ppb during the lockdown period. This can be attributed to less movement of light motor vehicles, motorcycles and heavy-duty vehicles. It can be observed that the carbon monoxide concentration was at peak at 11 am in the day in all three months,” the study stated.
The researchers noted that nitrogen oxide concentration showed a lower concentration of 3.1 ppb during the pre-lockdown period, which continued till first week of April 2020. In the case of nitrogen dioxide, the concentrations were 25.6 ppb during pre-lockdown and 6.3 ppb during lockdown period.
The study found that the concentration of ozone marginally decreased from February 25 to March 15 (19.5 ppb to 17.5 ppb) and then increased by over 50% by attaining a maximum of 48.4 ppb during the lockdown period.
“This increase in ozone concentration was primarily due to the downtrend in concentrations of nitrogen oxides, carbon monoxides, photochemical titration reaction of nitrogen oxides, carbon monoxide, volatile organic compounds, and methane with meteorological conditions,” the researchers said.