Maharashtra is anticipated to move from its current "vulnerable" orange zone to the "highly vulnerable" red zone in 2023 in terms of aerosol pollution, according to a study.
High aerosol amounts include particulate matter (PM2.5 and PM10) consisting of sea salt, dust, sulphate, black and organic carbon. If inhaled they can be harmful to people's health.
Aerosol Optical Depth (AOD) is the quantitative estimate of the aerosol present in the atmosphere and it can be used as a proxy measurement of PM2.5.
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The study -- “A deep insight into state-level aerosol pollution in India” -- by researchers Dr Abhijit Chatterjee, Associate Professor and PhD scholar Monami Dutta from Bose Institute, Kolkata, provides a national scenario of aerosol pollution with the long-term (2005–2019) trend, source apportionment, and future scenario (2023) for various Indian states. It was published in the peer-reviewed journal Elsevier in August this year, according to a press statement issued in Mumbai.
Maharashtra currently falls under the orange category which is a vulnerable zone with AOD between 0.4 and 0.5. However, the rising aerosol pollution is expected to push the AOD higher than 0.5 to enter into the most vulnerable (red) zone.
The values of AOD range from 0 to 1. 0. While 0 indicates a crystal-clear sky with maximum visibility, a value of 1 indicates very hazy conditions. AOD values less than 0.3 fall under the green zone (safe), 0.3-0.4 is blue zone (less vulnerable), 0.4-0.5 is orange (vulnerable) while over 0.5 is the red zone (highly vulnerable).
“According to our study, air pollution in Maharashtra has mostly been influenced by coal-based thermal power plants (TPP) in the past. Its capacity is increasing with the increase in demand for electricity. However, if the state continues to install the TPP capacity as observed in the past it would enter into the most vulnerable zone (mean AOD of the state will be higher than 0.5) which could result in an increase in morbidity rate, decrease in life expectancy along with other health issues of the people of Maharashtra,” Dr Chatterjee said.
Maharashtra can witness an AOD rise of about 7 per cent between 2019 and 2023, he said.
The study identified the main sources of aerosol pollution in Maharashtra to be thermal power plants, solid fuel burning and vehicular emissions.
The sources were assessed through three phases -- Phase I being 2005 to 2009, Phase II 2010 to 2014, and Phase III 2015-2019.
The contribution of emissions from TPPs increased from 31 per cent to 39 per cent between Phase I and Phase III (2005 - 2019), mainly due to the increase in capacity and dependence on coal-based power generation, the study said.
Over the years, the contribution of solid fuel burning to aerosol pollution has been declining from 24 per cent to 18 per cent while vehicular emissions have remained consistent throughout the three phases (14-15 per cent).
Maharashtra needs to turn down its TPP capacity by 41 per cent (10 GW) to move to the Blue Safe Zone, the study recommended.
“Maharashtra is highly influenced by Coal based ThermalPower Plants (In phase 3 i.e. from the year 2015-2019, the TPP contribution to air pollution is around 39 per cent. In order to control such threats, the State government should not only restrict further sanction of new TPPs but also should focus on reducing the current TPP capacity by at least 10 GW,” said Monami Dutta, the first-author of the study and Senior Research Fellow, Bose Institute, Kolkata.