Country with the worst air pollution

According to the IQAir 2020 World Air Quality Report, the country with the worst air pollution is Bangladesh, which has an average PM2.5 particulate pollution level of 77.1 μg/m³. This is a sharp decline on the level reported in 2018 (97.1 μg/m³), but still close to 8 times the maximum level considered acceptable by the World Health Organization.

The term "PM2.5" is used to describe airborne particulate matter with a diameter of less than 2.5 micrometres. The most common source for these fine particles is the smoke emitted by burning fuels for transportation and heating. Exposure to PM2.5 pollution is known to cause long-term health problems, particularly lung and heart disease.

Bangladesh's high levels of air pollution are the consequence of several factors. Firstly, Bangladesh has a lot of motor vehicles and few actively enforced emissions standards (although this is improving). Secondly, many homes in Bangladesh do not have any sort of central gas or electricity connection for heating and cooking, meaning that open fires and stoves are often used. Finally, there is little effective regulation of industry, with highly polluting factories able to operate in densely populated areas.