Dhaka's air quality continues to be worst in the world

The capital of Bangladesh ranked first among the world's cities with the worst air pollution on Wednesday (February 5), as Dhaka's air quality index (AQI) was found to be 269 (very unhealthy).

Dhaka has been occupying the top spot since February 2. 

On the second spot, Pakistan's Lahore had an AQI of 207, followed by India's Delhi at the third spot, with an AQI of 194.

'Good' AQI is between 0 and 50, where air quality is considered satisfactory, and air pollution poses little or no risk.

The AQI between 51 and 100 is termed 'moderate.' Pollution in this range may pose a moderate health concern for a very small number of individuals. People who are unusually sensitive to ozone or particle pollution may experience respiratory symptoms.

An AQI between 101 and 200 is considered unhealthy for sensitive groups.

 An AQI score between 151 and 200 is said to be 'unhealthy' while a range between 201 and 300 is considered 'very unhealthy.'

Meanwhile, the AQI range between 301 to 400 is ranked 'hazardous', posing serious health risks to residents.

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

Air pollution has always been a problem in Dhaka. Winter is often when the air quality deteriorates, and monsoon season is when it gets better.

According to the World Health Organization (WHO), air pollution kills an estimated seven million people per year throughout the world, primarily due to an increase in fatalities.

Health problems in children and adults can occur because of both short- and long-term exposure to air pollutants. Exposure to high levels of particulate matter, for example, can lead to reduced lung function, respiratory infections and aggravated asthma from short-term exposure.

On the other hand, long-term or chronic exposure to fine particulate matter increases the risk for diseases with a longer onset, like some noncommunicable diseases including stroke, heart disease, chronic obstructive pulmonary disease and cancer.