Heavy presence of NO2 making Dhaka air poisonous


Nitrogen dioxide has become a cause for serious concern as the concentration of the pollutant in Dhaka’s air is increasing while it is decreasing across the world.

This pollutant has implications for the production of “ozone” — another gaseous pollutant that can be harmful to human health.

A flagship study, conducted by the US-based organisation Health Effects Institute, said exposure to NO2 can irritate airways, aggravate existing respiratory diseases, raise the risk of asthma development in children, and increase the frequency and severity of asthma symptoms in children and adults.

South Asia is among the few regions in the world where NO2 levels are increasing in some areas.

Between 2000 and 2019, NO2 exposure in South Asia increased by 22 per cent, while global averages decreased by 5 per cent.

Data shows that in 2019, five cities in Bangladesh were among the top 20 cities with the highest NO2 levels in the region.

The cities exceeded the WHO Annual Air Quality Guideline for NO2 (10 µg/m3), with Dhaka having the highest level in the country at 23.6 µg/m3, followed by Chattogram with 21.3 µg/m3, Sylhet with 13.5 µg/m3, Rajshahi with 13.1 µg/m3, and Khulna with 11.0 µg/m3.

Meanwhile, Kathmandu (Nepal), Hyderabad (India), Bengaluru (India), and Karachi (Pakistan) had the highest NO2 levels in the region, in that order.


The report said a total of 31 per cent of fine particulate matter in the region comes from residential sources, including the use of solid fuels for heating and cooking.

Additionally, a growing fleet of personal vehicles and continued reliance on coal for energy production pose the challenge of increasing levels of NO2 and PM 2.5.

As many as 564,739 vehicles were due for regular fitness checks but did not take clearance as of April 30, according to Bangladesh Road Transport Authority data.

More than 50 lakh vehicles are plying the streets, and most of them are old.

Experts said that incompetent combustion of fuel, old and unfit vehicles, and low-quality fuel are the key reasons for the rise of NO2 levels in the air.

The air quality improves in the rainy season in Bangladesh due to showers, but in recent years it has been observed that the air quality remains poor even in the rainy season too.

Over the years, vehicles have become a major concern for air pollution in the big cities, and that’s why we see that air quality does not improve at an expected level in the rainy season.

No effort is seen to improve the air quality in Bangladesh.