The Covid-19 lockdown had swept clean Delhi’s air, significantly lowering the levels of pollutants temporarily, before “steadily rising back” with the opening up of businesses and transportation, an analysis by the Central Pollution Control Board (CPCB) shows.
The CPCB report, which was released Wednesday, states that in terms of particulate matter levels, PM2.5 had reduced by 24% during the pre-lockdown phase as compared to 2019, and nearly 50% during the first two phases of the lockdown. PM10 and NO2 showed a bigger drop of 60% and 64% respectively in the second phase of lockdown, also seen against similar period in 2019.
When compared against pre-lockdown levels, 38% and 33% reduction in PM2.5 and 37% and 30% reduction in PM10 was observed during the lockdown phase-I and phase-II in Delhi, the report adds.
The report, ‘Impact of Lockdown on Ambient Air Quality’, looks at air quality data in three phases: March 1-March 21, March 25-April 19 and April 20-May 3, and carries a comparative study of these periods with the corresponding time phases in 2019.
“The study revealed that sources associated with vehicular emissions, domestic/local coal combustion, waste incineration and urban organic aerosols reduced sharply from the pre-lockdown phase into lockdown phase-I and were found to steadily rise back with increasing relaxations in the lockdown,” the report states, quoting a study conducted by IIT Delhi and IIT Kanpur.
Overall, between March 25-May 3, the number of days with ‘Good’, ‘Satisfactory’ and ‘Moderate’ air quality index (AQI), as recorded by the CPCB, increased to 40 in 2020 as against 17 in 2019. There were no days with ‘Poor’, ‘Very Poor’ and ‘Severe’ AQI during this period in 2020 as against 23 in 2019.
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