The densely populated capital of Bangladesh has once again topped the list of world cities with the worst air quality.
Dhaka's air quality index (AQI) at 6.29 am read 489, considered 'severe'.
An AQI between 201 and 300 is considered 'poor', while a reading of 301 to 400 is said to be 'hazardous', posing serious health risks to city residents. And an AQI between 401 and 500 is said to be 'severe'.
Pakistan's Karachi and India's Kolkata occupied the second and third spots in the list of cities with the worst air quality, with AQI scores of 173 and 166, respectively.
AQI, an index for reporting daily air quality, is used by government agencies to inform people how clean or polluted the air of a certain city is, and what associated health effects might be a concern for them.
In Bangladesh, the overall AQI is based on five criteria pollutants – Particulate Matter (PM10 and PM2.5), NO2, CO, SO2, and Ozone (O3).
Dhaka has long been grappling with air pollution issues. Generally, the capital's air starts getting fresh when monsoon rains begin from mid-June.
In 2021, the average daily AQI score was 261 in January, 231 in February and 211 in March, which hit the record high in the last five years.
The average AQI scores were 247, 193 and 170 in January-March 2017 respectively, according to the analysis made by Prof Dr Ahmad Kamruzzaman Majumder, Founder and Director of Centre for Atmospheric Pollution Studies (CAPS), Stamford University, Bangladesh.
During these five years, the air quality was relatively better in 2020 as the average AQI scores were 235 in January, 220 in February and 175 in March in the year.
In January 2021, the air quality in Dhaka was hazardous (score 300+) for seven days, very unhealthy (score 200-300) for 23 days and unhealthy (151-200) for one day.
In the last three months, the highest average AQI score was 365 on January 20 and the lowest 144 on March 11, 2021.
Although the hazardous air quality poses serious health risks to residents, little is being done to check air pollution.
People are advised to avoid all outdoor exertion when the air quality is hazardous, said Dr Majumder, also chairman of the Department of Environmental Science of Stamford University.
What experts say
Experts say the exposure to a high level of air pollution weakens people's respiratory and immune systems, causes various cold-related diseases, making them more susceptible to Covid-19.
The World Health Organization (WHO) has also recently cautioned that the cities which have a higher level of air pollution should reinforce their preparedness against the deadly corona pandemic.
Experts also say the use of masks by all must be ensured by enforcing law and motivating people as it is the most effective way to protect oneself from pollution and Covid-19.