POST TIME: 22 November, 2019 00:00 00 AM
Dhaka air quality 3rd worst after Delhi, Lahore

Dhaka air quality 3rd worst after Delhi, Lahore

Bangladesh capital Dhaka was ranked third worst city in the Air Quality Index (AQI) yesterday with a score of 199 at 9am, indicating that the air quality was ‘unhealthy’. Pakistan’s Lahore and India’s Delhi occupied the first and second positions with a score of 417 and 338 respectively on the day.

For the past few days, the three major cities in Bangladesh, India and Pakistan have been registering the top three slots in terms of worst air quality. Dhaka ranked the worst in AQI for the third consecutive day on Tuesday. The air quality is categorised as good when the AQI score remains between 0-50 while the air is moderate when the number is 51-100.

When the score is between 101 and 150, the air is classified as unhealthy for sensitive groups. But a score between 151 and 200 means that the air is unhealthy and when the number is between 201 and 300, the air is classified as very unhealthy.

When the AQI value is between 201 and 300, every city dweller may begin to experience health effects.

Children, adults, and people with respiratory diseases are advised to avoid outdoor exertion while everyone else is suggested to limit outdoor exertion in this situation.

The AQI, an index for reporting daily air quality, tells people how clean or polluted the air of a certain city is, and what associated health effects might be a concern for them.

Bangladesh’s overcrowded capital has been grappling with air pollution for a long time.

“The air quality of Dhaka is not good, but it's in no way comparable with that of New Delhi,” Md Ziaul Haque, director (air quality management) of the Department of Environment said recently.

He said air quality usually declines during the dry months — from October to April — but improves during monsoon. “It becomes worse in the winter. Last winter, we had AQI readings of over 400 in Dhaka, but that was for just a few days,” he added.

The AQI index is based on the five criteria of pollutants—ground-level ozone, particulate matter, carbon monoxide, sulphur dioxide and nitrogen dioxide. AQI was introduced in 1968, when the National Air Pollution Control Administration of the US undertook an initiative to develop an AQI and apply the methodology to metropolitan statistical areas.

In Dhaka, Haque said, brick kilns were the major source of air pollution. “These kilns are mostly operated during the dry season as it is hard to run them during monsoon because of frequent rains.”

Also, construction work that kicks up dust, poorly-maintained vehicles that emit excessive harmful particles and toxic gases, and industrial air pollution are to be blamed for the pollution, the DoE director noted.

“Last year, half the air pollution in Dhaka was caused by brick kilns, while construction work contributed around 25 per cent and vehicle emission 10–12 per cent,” he said.

A five-year survey, conducted by the DoE, found that Narayanganj has the most polluted air, followed by Dhaka. Third is Gazipur, followed by Rajshahi, Chattogram, Khulna, and Barisal. The survey was conducted between 2013 and 2018 with funds from the World Bank (WB). Dr Mahadi Abdur Rauf, an associate professor of Northern Medical College, said the consequences of air pollution are pretty evident.

“Tens of thousands of people suffer from respiratory diseases per year in the country,” he added.