It had a score of 402 at 10:50 am. The air was classified as ‘hazardous’ and in this condition, everyone may experience more serious health effects.

When the AQI value is more than 300, people are advised to avoid all outdoor exertion.

India’s Delhi, Kolkata and Mumbai have occupied the next three positions in the list with scores of191,179 and173 respectively.

The poor air quality of Dhaka, one of the most polluted cities of the world, has become a cause of concern for its resident as there is a correlation between severity of Covid-19 infections and long term exposure to air pollutants.

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

Also read; No respite from pollution as Dhaka’s air quality still ‘unhealthy’

In Bangladesh, the AQI is based on five criteria pollutants - Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.

World’s most polluted country

Bangladesh topped the list of the world’s most polluted countries in 2019 for PM2.5 exposure, according to an IQAir AirVisual report.

The 2019 World Air Quality Report is based on data from the world’s largest centralised platform for real-time air quality data, combining efforts from thousands of initiatives run by citizens, communities, companies, non-profit organisations and governments.

Air pollution consistently ranks among the top risk factors for death and disability worldwide. Breathing polluted air has long been recognized as increasing a person’s chances of developing heart disease, chronic respiratory diseases, lung infections, and cancer, according to the report.

Also Read: Air Quality Index: Dhaka ranks 2nd worst

As per the World Health Organization (WHO), the air pollution kills an estimated seven million people worldwide every year largely as a result of increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections.

Over 80 percent living in urban areas which monitor air pollution are exposed to air quality levels that exceed WHO guideline limits, with low- and middle-income countries most at risk, WHO estimated.

What 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, according to experts.

Also Read: Dhaka's polluted air makes Covid fight harder

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.

The also said 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.