Dhaka air among the worst

Dhaka city again ranked as one of the most polluted in the world yesterday, according to the air quality index prepared by the US Environmental Protection Agency.

In the rating, the Bangladesh capital ranked fourth in a list of the most polluted cities in the world with an index value of 195.

Kathmandu was rated the most polluted with a value of 208.

According to the index, the air pollution level across the world varies from hour to hour and day to day.

In late February of this year, according to the same index, Dhaka ranked as the most polluted city in the world with a score of 339 and its air was classified as “very unhealthy.”

The index has six categories indicating growing levels of public health hazards.

An air quality value over 300 indicates hazardous air while below 50 is considered to be healthy air. "Unhealthy" AQI is 151 to 200. At its current level, “everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects”.

Statistics of Bangladesh's Department of Environment show that the air quality index had the highest score of 501 in Dhaka on March 11. It was 338 in Gazipur and 308 in Narayanganj on the same day.

Among all the cities of the country, the highest pollution in March was recorded in Narayanganj with a score of 538.

According to medical experts, dust concentration in the air usually increases five times during the dry season, and dust particles from construction sites worsen the situation. Inhaling dust can severely damage the respiratory system and cause various lung diseases as well as viral and bacterial infection.

In Dhaka, air pollution level significantly comes down during monsoon, according to the department's findings.

Air quality ranging from 0-50 is considered good, 51-100 is moderate, 101-150 caution, 151-200 unhealthy, 201-300 is very unhealthy and 301-500 is extremely unhealthy.