Breathing Guwahati air in winters is like smoking 25 cigarettes: Study
Black carbon, which is formed by incomplete combustion of fossil fuels, wood and other fuels, is part of fine particulate air pollution and contributes to climate change
Residents of Guwahati, nearly 2,000 km away from Delhi where people are experiencing alarming air pollution level these days, are not too far away from the biohazard as a study has shown that the city, which is the gateway to northeast India, is also prone to such high pollution levels, especially in winter.
A study by researchers at Indian Institute of Technology-Guwahati (IITG), published last year in the Urban Climate journal, showed that exposure to black carbon (BC) pollution in Guwahati in winter might cause health risks equivalent to passively smoking 25 cigarettes every day.
“The health risk estimate due to atmospheric BC in equivalent amounts of passive cigarette smoking was 25, indicating that reduction in BC is necessary through quick management strategies,” the study by professor Sharad Gokhale and research student Sameer Singh of IIT-G’s civil engineering department stated.
Black carbon, which is formed by incomplete combustion of fossil fuels, wood and other fuels, is part of fine particulate air pollution and contributes to climate change.
When inhaled, BC is deposited in lungs and can cause acute health problems including premature deaths, several studies have revealed. Black carbon is a short-lived pollutant with a lifetime of a few days to weeks, and it also affects cloud formation and rainfall pattern.
The study carried out real-time BC measurement in Guwahati during winter from January to March 2020. It found that BC concentration due to biomass burning was high throughout evening to night time as a result of cooking and heating during winter.
The BC concentration was high during night and early morning hours due to emissions from burning of fossil fuels by trucks and buses. The study found that while fossil fuels contributed to 70% of BC pollution in Guwahati, the rest 30% was due to biomass burning due to cooking, heating, etc.
The mean value of BC in Guwahati during the period of study measured at wavelength of 880 nm was 10 ± 4.72 micrograms per cubic metre (µg/m3).
“The level of black carbon concentration in Guwahati during winter was found to be very alarming. Unless measures are taken through policy intervention these values could keep on rising,” Gokhale said.
While the figures and the situation are alarming, experts say BC concentration can be brought down significantly by reducing emissions at source. Another study done by the same team during different phases of lockdown in 2020 due to COVID-19 indicated this.
While lockdown was done in four phases from March 25 to May 31, sampling for the study was done in six phases – one pre-lockdown stage (from February 12 to March 21), four lockdowns and a post-lockdown stage (from June 7 to July 3).
The study published this year in the Journal of Earth System and Science found that BC concentration was the maximum during pre-lockdown and post-lockdown when there were no constraints on industrial, vehicular or other anthropogenic activities.
According to the study, the BC level due to the burning of fossil fuels was reduced to 67% in the first phase of lockdown and 74% in the second phase. On the other hand, the BC fraction due to biomass burning was found to be reduced from 0.78 to 0.51, the study found.
“The sudden decrease in BC concentrations during the various lockdown phases showed that the control at the origins of anthropogenic activities could improve air quality,” the study said.
“If measures like emphasis on the use of more CNG and electric vehicles are taken, BC concentrations can be reduced significantly, which in turn will improve air quality and also help in bringing down health problems,” Gokhale said.