Air quality in Bangladesh: A matter of great concern

Hopefully, we learned many lessons from the ongoing Covid-19 pandemic. One of them is the importance of oxygen for our survival. Normally it is available free of cost. As a matter of fact, we take the supply of oxygen for granted. Recently, however, we heard stories of Covid-19 patients with breathing difficulties moving from one hospital to another in search of oxygen. At one stage, oxygen became so scarce that many patients had to pay tens of thousands of taka as hospital bills only for the supply of oxygen. Yet we are alarmed to find how we have been polluting the air that is our main source of oxygen supply.

Air quality in Bangladesh was the worst in the world, while its capital Dhaka, was the second most polluted city in 2020, in terms of air pollution, said a global report (DS, March 18, 2021). “South Asia remained the most polluted region of the world with Bangladesh, India and Pakistan sharing 42 of the 50 most polluted cities worldwide,” according to IQAir’s global air quality data platform in its World Air Quality Report 2020. The three countries just mentioned, are also at the top of the list of countries with the worst air quality.

The report published recently said that the average annual PM 2.5 concentrations in Bangladesh was 77.1 microgrammes per cubic metre (mcg/m3) of air, which is seven times above WHO’s exposure recommendation. PM refers to particulate matter in air. It consists of a mixture of solid and liquid particles suspended in the air. While particles with a diameter of 10 microns (micrometres) or less, denoted as PM 10, can penetrate and lodge deep inside the lungs, the smaller particles with a diameter of 2.5 microns or less, denoted as PM 2.5, are the more damaging to health as they can penetrate the lung barrier and enter the blood system.

Researchers from IQAir, a global air quality information and Swiss-based tech company, analysed pollution data from 106 countries, specifically measuring PM 2.5 that can cause serious health risks. “An estimated 13-22 percent of deaths in this region are linked to the health effects of air pollution exposure, with associated estimated costs equating to 7.4 percent of the region’s GDP,” the report said. Obviously, the cost due to air pollution is huge.

Chronic exposure to particulate matter (PM 10 and PM 2.5) can cause cardiovascular and respiratory diseases, as well as lung cancer. There is a close correlation between exposure to high concentrations of small particulates (PM 10 and PM 2.5) and increased mortality or morbidity. Conversely, when concentrations of small and fine particulates are reduced, related mortality will also go down. This correlation helps policymakers to plan the population’s health improvements if air pollution is reduced.

Small particulate pollution has health impacts even at very low concentrations. Therefore, the WHO 2005 guideline limits aim to achieve the lowest achievable concentrations of PM. The air quality guideline values for PM 2.5 are 10 mcg/m3 for annual mean and 25 mcg/m3 for 24-hour mean. The corresponding values for PM 10 are 20 mcg/m3 and 50 mcg/m3..

According to the report, only 24 out of 106 monitored countries met the WHO’s annual guidelines for PM 2.5 in 2020, even though air quality improved globally due to the Covid-19 pandemic. “The year 2020 brought an unexpected dip in air pollution. In 2021, we will likely see an increase in air pollution due to human activity again,” said Frank Hammes, CEO of IQAir. Here we find a correlation between air quality and the Covid-19 pandemic. Human activities were curtailed significantly in many countries due to the lockdowns. This means that there were less discharge of exhaust from automobiles and fossil fuel based power plants, fewer pollutants from industries and less construction works. Obviously, these are the major sources of air pollution in most countries.