NEW DELHI: Significant improvement in air quality was observed during the coronavirus-induced lockdown due to restricted anthropogenic activities, but such air quality management strategies come with considerable economic costs, the Central Pollution Control Board (CPCB) said on Wednesday.
According to the 'Impact of Lockdown on the Ambient Air Quality' report, released during the virtual celebrations of the 46th Foundation Day of CPCB, PM2.5 reduced by 24 per cent during the pre-lockdown phase and further reduced by almost 50 per cent during the lockdown phases as compared to levels observed during 2019.
The report was released by Minister of State for Environment Babul Supriyo, who praised the CPCB for its contribution in checking and spreading awareness about air pollution.
"CPCB has been working very diligently for the last four decades. It has played a very important part in India's growth. It created awareness and conscience about the importance of air we breathe," Supriyo said.
The CPCB report considered the pre-lockdown phase from March 1-21, Lockdown phase-I from March 25-April 19 and Lockdown phase-II from April 20 to May 3.
"Considerable improvement in air quality levels were seen as compared to the same time periods in last year. It has also been noted that air quality levels were improved even during the pre-lockdown period in 2020. This may be due to meteorological conditions as well as the fact that a few restrictions such as those on cinema halls, schools, colleges, etc. were already in place during the first half of March."
"In terms of Particulate Matter levels, while PM2.5 reduced by 24 per cent during the pre-lockdown phase, it further reduced by almost 50 per cent during both lockdown phases as compared to levels observed during 2019. PM10 reduced by a massive 60 per cent, with NO2 levels falling by 64 per cent, Benzene by 62 per cent and SO2 by 35 per cent, during the second phase of lockdown as compared to levels in the same time period in 2019," the report said.
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.
"Although significant improvement in air quality was observed during lockdown due to restricted anthropogenic activities, such air quality management strategies come with considerable economic costs.
Irreversible emission reductions through sustainable process changes and long-term objectives is crucial for achieving good air quality levels.
"However, as the impact of various anthropogenic activities is now being quantified, actions that can be integrated in business as usual scenarios need to be identified, with emphasis on reduction of emissions at source including dust control, vehicular emissions, industrial operations, etc," it said.
The report said that lessons learnt from the COVID-19 pandemic can be utilised to target source specific actions leading to maximum improvement in ambient air quality.
"Further, socio-economic development and industrialization also needs to be in tandem with the carrying capacity of a city," it said.
According to the report, across India, workplaces mobility dropped by 56.7 per cent and by 81.3 per cent in Delhi during lockdown period (from March 24 to April 30) from the baseline average (from February 15 to March 23) which also corroborates with the period of least contribution to PM2.5 levels from traffic emissions.
"Across India, transit station mobility i.e. visit to public transport facilities dropped by 66 per cent (up to April 30, 2020) and by 77.7 per cent in Delhi from the baseline average," the apex pollution control body CPCB said.
The report said that during lockdown phase-I wherein maximum restrictions were imposed, contribution of vehicular emissions reduced to 5 per cent from 19 per cent during pre-lockdown phase.
"It was also observed that contribution from vehicular emissions to inorganic species in PM2.5 were found to be an appreciable amount (14 per cent) only in the pre-lockdown phase, while for all consequent phases the factor was found to contribute only in trace amounts. Similarly, both the coal combustion and waste incineration factors, which were found to be originating from local/domestic sources decreased steadily," it said.
As per the report, during the lockdown, in Delhi, the number of 'Good', 'Satisfactory' and 'Moderate' AQI (Air Quality Index) days increased to 40 in 2020 against 17 in 2019, and there were zero 'Poor', 'Very Poor' and 'Severe' AQI days in 2020 against 23 in 2019.
The air pollution reduction trend in NCR towns was similar to that of Delhi with reduction in certain pollutants, more prominent in NCR towns.
"Over 50 per cent reduction in PM2.5 and PM10 levels were observed during the first phase of lockdown in most neighbouring towns with sharp improvement in Gurugram with 61 per cent reduction in PM10 levels and Ghaziabad with 54 per cent reduction in PM2.5 levels as compared to 2019 levels," the report said.
"PM10 levels further reduced by over 60 per cent in Gurugram, Noida and Ghaziabad, in the second phase of lockdown, as compared to 2019 levels, in all likelihood due to restriction on dust generating activities," it said.
The report has been prepared under the supervision of Prashant Gargava, Member Secretary, CPCB in collaboration with IIT Delhi and IIT Kanpur.