Dhaka air quality fourth worst among world’s cities

Dhaka has recorded the worst air quality of the winter season so far on Saturday, with the Air Quality Index, or the AQI, recorded by international air quality tech company IQAir at the “very unhealthy” level, even on the weekend.

At 11am on Saturday, IQAir said Dhaka’s AQI stood at 198, ranking fourth worst in the world in terms of air pollution. Only three cities ranked worse – India’s Kolkata, Delhi, and Mumbai.

The Bangladesh Department of Environment, which gives immediate updates on air quality, said that Dhaka’s AQI score was 201 at 11am, which is considered “very unhealthy”.

Air quality is usually measured by the amount of floating fine particulate matter, called PM-10, and the amount of floating ultrafine particulate matter, or PM 2.5, which is measured in micrograms per cubic metre (parts per million-ppm).

To get an accurate measure of the level of pollution, the AQI is prepared after considering the PM 2.5, PM 10, as well as sulphur dioxide, carbon monoxide, nitrogen dioxide, and ground level ozone.

AQI levels between 0-50 are considered good, 51-100 are considered moderate, 101-150 are considered unhealthy for sensitive groups, 151-200 are unhealthy for everyone, 201-300 are very unhealthy, and 301-500 are hazardous.

Keeping Dhaka’s air quality score within 200 during winter is the biggest challenge, said Ziaul Haque, director (air quality management) of the Department of Environment.

 “In the past, during winter, the AQI score usually ranged from 250 to 300, making it risky. This time, we are trying to keep it within 200, although keeping it at this level is a very difficult and challenging task.”

Twelve mobile courts are working across the country to control pollution. Out of these, eight are working around the clock in Dhaka and its surrounding districts.

Maintaining air quality is not the job of a single ministry. Along with transport, business and industry, it also involves the habits of the public, Ziaul said: “Pollution from the districts surrounding Dhaka also reaches Dhaka. We have set a deadline for six months to remove old vehicles that spew black smoke from the transport sector. Hopefully, the air quality will not get too bad this time. The public also needs to cooperate.''

The Department of Environment has decided not to grant any new permits and environmental clearances for brick kilns to control air pollution.

The agency's website has made an announcement regarding the “very unhealthy” air, saying that the air quality in Dhaka and its surrounding districts is occasionally going from “very unhealthy” to “hazardous”. It urged people to use masks when going out and for sensitive people to not go outside unless absolutely necessary.

The air quality in Dhaka and across the country deteriorates during the winter, which is also the dry season. The transport of sand and cement for construction work, the operation of brick kilns, and smoke from unfit vehicles leads to the worsening of the air pollution.