Kathmandu, the capital city of the country, has become the third most polluted city in the world. The air quality index (AQI) of Kathmandu, measured at 4:45 pm on Tuesday, reached 150.

According to Air Quality Air, a site that measures the world's air quality, Dhaka, the capital of Bangladesh, and Hanoi, the capital of Vietnam, are in the first place. Dhaka's AQI is 166 and Hanai's is 154. 

Since the last few days, Kathmandu's atmosphere has deteriorated and the air has become polluted. Similarly, on Monday, Kathmandu came to the first number of the world's most polluted city. 

In the absence of sufficient rain, the sky of Kathmandu Valley becomes polluted in winter. An AQI of 50 is considered satisfactory and 150 to 200 is considered unhealthy.

For a healthy environment, the amount of particles smaller than 2.5 microns in diameter (PM 2.5) in the air should be 5 micrograms per cubic meter or less. However, it is found that its maximum amount is 120.57 in Kathmandu. These particles contain nitrates, sulphates, black carbon, ammonium and dust particles which are considered very harmful for health.