On Saturday, it ranked 24th in the world for air pollution, down from 1st in February
With fewer vehicles plying Dhaka's roads—because of the Eid holidays—and frequent rainfall, Dhaka's air quality has improved.
It has ranked 24th on the world Air Quality Index (AQI) – a considerable leap from the top position it generally occupies among cities with the worst air pollution.
On real-time rankings, Dhaka scored 71 on Saturday, according to AirVisual, which monitors global air quality. It was classified as "moderate."
Just a month ago, on May 9, Dhaka ranked as the third-worst polluted city; while on February 19, it topped the index, with the air classified from "very unhealthy" to "hazardous," respectively.
Meanwhile, Dubai in United Arab Emirates was ranked the city with the worst air quality, with a score of 158; and Brazil's Sao Paulo came second with a score of 148.
As one of the most densely-populated countries in the world, Bangladesh has been struggling with air pollution for a long time. Dhaka continuously ranks among the world’s most polluted cities.
Brick kilns, vehicles run on fuel containing high levels sulphur, as well as construction work, have all been identified as major sources of air pollution.
Air quality further declines during the dry months—from October to April—but improves during the monsoon.
The United States Environmental Protection Agency developed the Air Quality Index (AQI) to measure air quality. The AQI is divided into six categories, indicating increasing levels of harm to one’s health.
An AQI value over 300 represents hazardous air quality, and air quality below 50 is good.
The index is based on the five criteria of pollutants regulated under the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulphur dioxide, and nitrogen dioxide.
The AQI debuted in 1968, when the National Air Pollution Control Administration undertook an initiative to develop an air quality index, and to apply the methodology to Metropolitan Statistical Areas.