Air pollution is a big problem for the people of the world . For a long time, the level of air pollution in different cities of the world is gradually increasing. Due to the abnormal increase in air pollution, the risk of death of various animals including humans is increasing. Air pollution is also increasing in the densely populated Dhaka.

Bangladesh ranked fifth with a score of 130 in the list published by IQAir, an international air technology company, at 10:40 am on Monday (07 October).

At the same time, Pakistan's Lahore tops the list of the world's most polluted cities, with a score of 171. Apart from this, Hanoi, the capital of Vietnam, is in the second position with a score of 159. India's Delhi is third with a score of 156 and Mongolia's Ulaanbaatar is fourth with a score of 152.

The Air Quality Index (IQAIR) is published by Switzerland-based air quality monitoring technology company. The AQI index is based on the moment-by-moment air quality and gives people information about how clean or polluted the air is in a particular city. And they inform whether any kind of health risk can be created or not.

An AQI score of zero to 50 is considered good. 51 to 100 is considered tolerable or moderate. And for sensitive groups, a score of 101 to 150 is considered unhealthy.

151 to 200 is considered unhealthy. Similarly, an AQI score of 201 to 300 is considered very unhealthy. And if it is more than 301 it is considered as disaster.

Air pollution poses serious health risks. It is harmful to people of all ages. However, air pollution is very harmful for children, sick people, elderly and pregnant women.

AQI in Bangladesh is determined based on 5 characteristics of pollution. They are Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone (O3).

According to a report by the Department of Environment and the World Bank in March 2019, the three main sources of air pollution in Dhaka are brick kilns, vehicle fumes and dust from construction sites.

According to the World Health Organization (WHO) , air pollution has increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections. It causes an estimated 7 million deaths worldwide each year.