NEW DELHI: Both PM2.5 (Fine Particulate Matter) and NOx (Nitrogen Oxide) levels in Varanasi have remained above Central Pollution Control Board’s (CPCB) safety limit for the last three years consistently, an analysis by NCAP (New Car Assessment Program) Tracker, an air pollution policy monitoring platform, has established.
CPCB prescribes 40 ug/m3 annual average as the safety standard for both PM2.5 and NO2 (Nitrogen Dioxide) levels. PM Modi’s Parliamentary Constituency requires air pollution management in its smart city plans.
PM2.5 in the city for three consecutive years till 2021 has been 96, 67 and 61 respectively. The year 2020 is counted as an anomaly period by most experts, when evaluating air pollution, due to lockdown impacts on emitting sources. For 2021 the data has been taken till 12 December. Meanwhile, NO2 levels have been 55, 31, and 53 ug/m3 respectively for the last 3 years.
Vehicular emissions are one of the key sources of nitrogen dioxide pollution, along with sources like fossil-fuel-based power plants, incineration plants, wastewater treatment facilities, glass and cement production facilities, and oil refineries.
The data has been evaluated from Continuous Ambient Air Quality Monitoring Systems (CAAQMS) set up in Varanasi. In 2021, two monitors were added in June and another in July making it a total of 4. But as these three monitors do not make up about 70% of monitored days for the annual average, so only the monitor that was present in 2019 and 2020 is considered for annual comparisons.
The WHO’s prescribed safety limits for NO2 are 25 ug/m3 for daily average and 10 ug/m3 for annual. In India, the meteorological condition is highly conducive for rapid conversion of the precursor gases like nitrogen dioxide and sulphur dioxide (NO2 and SO2) to secondary PM2.5. Hence, to control PM2.5, the emission control of the precursor gases is necessary. Local-level exposure to NO2 leads to a range of environmental and health impacts as well.
Aarti Khosla, Director, Climate Trends said, “This data gives a clear idea of what goes into making PM2.5 particulate and that we must have this knowledge before taking steps to reduce pollution. Focusing on such information should allow the local and state governments, the Centre, as well as citizens, to know where to act. Having year-long above-average concentrations of nitrogen dioxide which is evidently in busy traffic or high-density industrial areas shows where action should be.
Varanasi as one of the Smart Cities is undergoing massive infrastructure project development, the power shortages are compensated for by diesel gensets like most tier 3 towns in India and unlike the 15 years limit for scrapping old vehicles in Delhi, Uttar Pradesh’s transport scrappage policy allows for 20 year old vehicles to ply on the roads. With limited resources for monitoring and compliance, vehicles older than 20 years may also be plying on the city roads and interior lanes, adding to transport emissions in the city.
A 2018 source apportionment study by Banaras Hindu University (BHU) on local and distance sources of urban PM2.5 in Varanasi identified traffic as the major probable local source which contributed the maximum to high PM levels followed by paved road dust and local combustion activities. Land use regression analysis also identified traffic variables such as heavy vehicle intensity, distance from the highway, traffic intensity (within 500 m buffer), and percentage of green cover as major factors influencing PM2.5 distribution in the city.
Along with meteorological factors, NO2 and Carbon Monoxide (CO) were also identified as major gaseous air pollutants which modified PM concentrations in the holy city.
Prof S N Tripathi, Civil Engineering Department, IIT Kanpur & Steering Committee Member, National Clean Air Programme, MoEFCC said, “The air pollution level seems to be exceeding the safe limits prescribed by CPCB. Dense monitoring using sensors under smart city projects can help track and mitigate pollution sources. E buses can also help in reducing vehicular pollution in a substantial way.”
As continuous monitoring in the city started only in 2015, a study conducted jointly by BHU and Indian Institute of Technology (IIT) Delhi examined 15 years of satellite and climatology data for Varanasi establishing a rapid (1.5-3%) per year increase in PM2.5 in the period, with 87% days in a year experiencing persistence of PM2.5 levels above the national air quality standards. It translates to a burden of 5700 annual premature deaths (0.16% of the population), of which 29%, 18%, 33%, 19%, and the remaining 1% are attributed to ischemic heart disease, stroke, chronic obstructive pulmonary disease, acute lower respiratory infection and lung cancer respectively.