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Average concentration of harmful black carbon has spiked in parts of city over last decade

Black carbon emission in Bengaluru has gone up considerably over the last decade, researchers have highlighted.

Researchers from the Indian Institute of Tropical Meteorology, New Delhi, Visvesvaraya Technological University, Belagavi, Ghousia College of Engineering, Ramanagara, and Dayananda Sagar College of Engineering, Bengaluru, studied concentration of black carbon at five different locations in Bengaluru.

They noted that the average concentrations of this harmful pollutant have increased by around 55% in urban regions within five years from the time of the study, indicating the adverse impact of human activities. Black carbon values were measured at the City railway station, Peenya Industrial Area, Corporation Circle, Malleswaram, and Jayanagar from January 2019 to December 2019.

While the overall average concentration of black carbon was found to be 5.91 µg/m3, a higher concentration of 7.71 µg/m3 was recorded over the city railway station, and the lowest (3.69 µg/m3) was in Jayanagar.

Hotspots
Black carbon emission was also found to be 41% higher in heavy traffic and industrial locations than in residential areas, indicating that a large portion of the emission is mainly from fossil fuel combustion.

The concentrations of black carbon during monsoon were very low (3.4 µg/m3) as compared to winter (9 µg/m3) due to the washout effect.

Black carbon is a sooty material that comes from the incomplete combustion of fossil fuels, biofuels, and biomass. It is emitted from diesel engines, coal-fired power plants, cook stoves, and forest fires.

The study underlines that a higher mass concentration of black carbon indicates serious implications for the regional climate that need to be investigated and mitigated.

Immediate action is required to mitigate the emission into the urban environment in the southern part of India.

Experts say the harmful gas absorbs sunlight and generates heat in the atmosphere. It can cause respiratory diseases and harm the cardiovascular system.

While waste burning also emits a small amount of black carbon, diesel combustion is the major source.

“Black carbon is a component of PM2.5. People in Bengaluru are exposed to high levels of black carbon. A majority of the emission comes from diesel combustion - both generator sets and heavy vehicles.

When we conducted emission inventory for Bengaluru, diesel generator sets were found to be contributing 11% of the total PM2.5 concentration, and diesel trucks and cars led to 63% of the total PM 2.5 emissions,” said Dr. R Subramanian, sector head, of Air Quality, Centre for Study of Science, Technology, and Policy (CSTEP).

Getting rid of diesel vehicles is the only way out. Most of the black carbon emission is from BS II, III, and IV vehicles and as they get phased out in favour of BS XI vehicles, the emission should come down, opine experts.