Scientific Community Worried About Kolkata’s Rising air Pollution Level

Kolkata: Dr Gufran Beig, a noted meteorologist, scientist and winner of the Shanti Swarup Bhatnagar Award, has raised the alarm about the air quality of the Eastern Metropolis of Kolkata. 

Talking to Newsclick, Beig said, “At present, the air quality of Kolkata remains well within the National Ambient Air Quality Standards (NAAQS) for 262 days and violates the safe limit for 103 days in a year as compared to Delhi’s 139 days within NAAQS and 226 days above standards.”

“This tends to suggest that Kolkata’s air quality is relatively better than Delhi. However, if emissions from the top three sectors contributing to PM 2.5 (particulate matter), e.g. transport, industry and waste burning, are not controlled, Kolkata will catch up to Delhi sooner than later,” he said. 

PM 2.5 are deadly fine particles emitted from the transport and allied sectors and are the most significant contributor to the city’s already deteriorating air quality, as shown by a recent study on the emissions inventory of Kolkata’s air quality. The study was published jointly by a team of scientists of Utkal university led by Dr SK Sahu and the National Institute for Advanced Studies led by Beig. The meteorologist is also the founding project director of the System of Air Quality Weather Forecasting and Research (SAFAR). 

It is the first time the researchers have mapped the sources of particulate matter (PM) pollutants like PM 10 and PM 2.5 with a resolution of 400 metres. This means that the city can have information on sources of pollution for every 400 by 400 metres grid area.

Researchers and air quality experts believe that emission estimates in such high resolution have the potential to serve as an essential information base for scientists, policymakers, the National Clean Air Programme and the West Bengal Pollution Control Board.

Air has suspended particulate matter of different sizes. Many of these are a complex mixture of dust, pollen, soot, and smoke and are hazardous. Of this, PM 2.5 is the smaller kind, with a diameter of not more than 2.5 micrometres. PM 2.5 is considered to have a significant health impact as it can stay in the air for days or weeks and is small enough to invade the lung’s airways. PM 10 is a relatively bigger, coarse particle with a diameter of 10 micrometres or smaller.

The study titled “A Comprehensive High Resolution Gridded Emission Inventory of Anthropogenic Sources of Air Pollutants in Indian Megacity Kolkata” was published in the reputed international journal “SN Applied Science of Springer Nature”. 

According to the study, the increase in fleet volume and the movement of an ageing vehicle fleet are the primary reasons for road transport emissions. Densely condensed small to medium-scale industrial unit zones are also reasons for elevated industrial emissions in Kolkata. A total of 14 sources of anthropogenic emissions were explored for Kolkata as part of the study, including sectors like wind-blown dust, transport, industry, power plants, households, slums, street vendors, crop residue burning cow dung, diesel generators, municipal solid waste burning, construction, incense sticks, mosquito coils and crematoriums.

As per research, transport (22%), followed by industry (18%) and power plants (15%) are the top three sectors in PM 10 emissions, whereas transport (32%), industry (18%) and municipal solid waste burning (16%) were the top three sources for PM 2.5 emissions.

Beig said, “The emerging sector like municipal solid waste burning has become one of the most prominent sources of emissions. Regulations on prohibition and banning of uncontrolled open burning of municipal solid waste should be implemented. Easy accessibility and consumption of low-cost solid fuels as the primary fuel for residential and commercial cooking activities in slums make it another responsible emerging sector.”

According to the West Bengal Pollution Control Board and Kolkata Municipal Corporation, Kolkata generates around 4000–4500 metric tonnes of solid waste per day. This bulk of waste is entirely dumped at its only landfill site i.e. Dhapa. Located towards the eastern fringes of the city, this landfill site is spread across about 35–50 hectares and has been functional since the 1980s. 

Currently, in India, around 23% of total municipal solid waste generated is treated, 43% is landfilled and the rest 34% is openly burned to prevent the dumping ground from overflowing with waste. Considering this, as there is no municipal solid-waste-to-energy plant within Kolkata city, it was assumed that about 70% of the waste is dumped and the rest 30% is openly burnt right away.

One of the important recommendations made by the scientists is that Dhapa should possibly have another alternative approach to treating the waste and ageing commercial vehicles should be discarded from the city’s traffic system.

Another study by the Energy Policy Institute at the University of Chicago has formulated the air quality life index (AQLI), a pollution index that translates PM 2.5 pollution into the most critical metrics. Developed by Economist Michael Greenstone and his team, the AQLI is rooted in recent research that quantifies the relationship between long-term human exposure to air pollution and life expectancy.

According to AQLI, West Bengal is India’s seventh most polluted state, with an average PM 2.5 concentration of 65.4µ/m3. If West Bengal were to reduce its average PM 2.5 pollution to the level prescribed by the World Health Organization guideline (5µ/m3), it would be adding 5.9 years to the life of its average residents. If it is reduced to the national standard, it would still add 2.5 years to people’s life expectancy.

The AQLI report also indicates that the air quality in the entire state deteriorated by more than 90% between 1998 -2020.

According to Dr Deepanjali Majumdar, senior scientist of NEERI, West Bengal has seven of the 132 non-attainment cities under the National Clean Air programme. Kolkata, Howrah, Haldia, Barrackpore, Durgapur, Asansol and Ranigunge are the non-attainment cities in the state. The primary aim of the programme is to take the 2017 pollution level as the base and have a 20% to 30% reduction in it by 2024. Under this pollution source, an apportionment study and a micro action plan are being created, keeping in mind the city-wise variations.

Talking to Newsclick, Majumdarappealed that “Air Pollution is a problem that should be mitigated in the interest of all residents, and it affects all socio-economic strata. As a citizen, people should take immediate action if they see garbage burning, and they should restrain themselves from doing so as well.”