Nagpur air gets cleaner after lockdown, finds NEERI study
   Date :19-Apr-2020

Citys greenery _1 &n
 City’s greenery is thriving amid lockdown to contain COVID-19. Even air quality has improved in Nagpur city as number of vehicles plying on roads has come down since March 21. (Pic by Satish Raut)
 
 
Staff Reporter :
 
A study by CSIR-National Environmental Engineering Research Institute (CSIR-NEERI) has found that the air quality of Nagpur has ‘improved sharply’ during lockdown in the wake of COVID-19 outbreak. The improvement in air quality has been attributed to stringent travel restrictions and shutting down of non-essential activities including those of air polluting sectors. CSIR-NEERI carried out a study on ‘Impact of the lockdown on air quality of Nagpur’. Dr Neel Kamal, Principal Scientist, CSIR-NEERI, analysed the data collected before and after the lockdown to probe into the air quality of Nagpur. A press release issued by CSIR-NEERI stated that the data collected from Continuous Ambient Air Quality Monitoring Station (CAAQMS) installed at Civil Lines, Nagpur was analysed to evaluate the air quality of Nagpur before and after the lockdown.
 
The monitoring period before the lockdown was February 20 to March 20 when all activities were normally in operation. In order to compare and derive conclusions with regard to the air quality of Nagpur, monitoring was also done during the lockdown between March 21 and April 17. Since the lockdown was imposed, the air quality in Nagpur has shown drastic improvement due to eradication of local pollutants generated from various activities. The lockdown led to a significant reduction in the major criteria air pollutants namely PM10, PM2.5, and nitrogen dioxide (NO2). PM or Particulate Matter is a mixture of solids and liquid droplets floating in the air.
 
The daily mean value of PM10 observed reduced from 61 µg/m3 to 47 µg/m3. PM2.5 level came down to 23 µg/m3 from 31 µg/m3. NO2 lowered down to 25 µg/m3 from 48 µg/m3. The fall of NO2 indicates that vehicles were not plying on roads and the existing guidelines on lockdown measures were strictly complied with, stated CSIR-NEERI on Saturday. The major air polluting activities in Nagpur have been emissions from vehicles, re-suspension of road dust due to movement of vehicles, fuel usage in hotels, construction activity, thermal power plants of Koradi and Khaparkheda, stated CSIR-NEERI.
 
Hourly variation of PM2.5 indicated the absence of these air polluting activities in Nagpur during lockdown, pointing out minimal air pollution in Nagpur. CSIR-NEERI study found that after 6 pm, PM2.5 level increased due to temperature inversion that restricted vertical movement of pollutants. CSIR-NEERI quoted Dr Neel Kamal as stating that PM10 and PM2.5 concentrations during lockdown could be considered as background levels for the city, excluding the impact of power plant. Background concentration is the ambient level of pollution that is not affected by local sources of pollution. The data further reveals that the wind flow at 240 m height above ground was from North-West and South-West during February to April 2020.
 
Therefore, Dr Neel Kamal reckoned that this wind flow caused the power plant emissions to move away from Nagpur city towards Kamptee area, thereby keeping Nagpur city’s atmosphere clean. The daily average of sulphur dioxide (SO2), which is an indicator of fossil fuel combustion, was found 9 µg/m3 before the lockdown and 2 µg/m3 during the lockdown, which is far below the regulatory limit of 80 µg/m3 recommended by Central Pollution Control Board, Delhi. Dr K V George, Senior Principal Scientist and Head, Air Pollution Control Division, CSIR-NEERI, also was associated with this study.