People in Bangladesh every day inhale an alarming amount of black carbon, a particle not only harmful to human health but also responsible for global warming.
But it is hardly monitored in the country though there has been a national action plan in place since 2018.
Black carbon has many damaging consequences upon inhalation, including increased rates of cancer, scarring of the lung tissue and heart damage as it can enter the blood stream via the lungs.
There is no permissible level for black carbon in the air.
In Dhaka, its amount is 10 to 15 micrograms per cubic metre, compared with 0.1 to 0.5 microgram per cubic metre in cities of developed countries, Dhaka University Professor Abdus Salam, an air pollution researcher, said.
Prof Salam added that they found burning of biomass - wood, dried leaves, garbage and agricultural waste - most responsible for black carbon emissions in Bangladesh. Transportation with coal burning accounts for the rest.
Black carbon, which does not last long in the atmosphere, is a key component of fine particles, or particulate matter 2.5 (PM2.5) - tiny particles or droplets in the air that are 2.5 microns or less in width.
Dr Tanvir Ahmed, a civil engineering professor at Buet, said black carbon is not routinely monitored in Bangladesh, therefore its concentrations from direct measurements are not available. But it can be assumed that if PM 2.5 rises, black carbon too goes up proportionately, he added.
Black carbon has a number of disastrous consequences on the environment and climate, as well as affecting the temperature within a city, having knock-on effects on the quality of people's lives, according to IQAir, a Swiss air quality technology company.
"And with large accumulations of this taking place due to its heavy release from factories, brick kilns and vehicles, it would be found in high amounts permeating both the atmosphere and roads across Bangladesh," it said in its 2021 World Air Quality Report.
The report puts Bangladesh on top among the most polluted countries in terms of air quality while Dhaka is the second most polluted capital in the world after New Delhi.
Researchers say the poorer the quality of air is, the more black carbon exists in the environment.
Prof Salam said though black carbon is a major air pollutant, the government has done little to tackle its emission despite embarking on a national action plan. If it is controlled, the temperature of the country could be reduced by at least 1 deg C, he also said, recommending immediate measures.
- This story was published by the Daily Star in March.