INDORE: The Air Quality Index in Indore, the country's cleanest city, breached the 400 mark on Friday, indicating that the air quality has reached the 'severe' category in Madhya Pradesh's financial capital.
According to the State Pollution Control Board data, the AQI in the city's Chhoti Gwaltoli area was pegged at 404 at noon, while the PM 2.5 (particulate matter) average was recorded at 255.26.
The average level of PM 10 in the city was 318.08. Chhoti Gwaltoli is a densely populated area of the city that sees heavy vehicular movement.
Dr Dilip Vaghela, an environmental expert and former official of the state pollution control board, told PTI, "The city started with loud Diwali fireworks from Thursday morning which continued till late night."
The situation continued in many areas on Friday also. This is the main reason for the air quality in the city reaching the severe category. The city's air quality usually remains in the "satisfactory" (AQI 51-100) category, the expert said.
According to the India Meteorological Department, the wind speed in the city was recorded at zero km per hour at 08.30 am on Friday.
Due to calm winds, pollutants could not get scattered here and there and settled in one place, further worsening the air quality in the city, Vaghela said.
According to a study by Clean Air Catalyst, a global coalition working to improve air quality, vehicular pollution and road dust are the highest contributors (70 per cent) to the deterioration of air quality in the city in normal times.
As per the MET department, an AQI between 0 and 50 is considered good, 51 and 100 satisfactory, 101 and 200 moderate, 201 and 300 poor,301 and 400 very poor, and 401 and 500 severe.
On the ground, however, Indore has been a model city for waste management.
In January, it was ranked as the cleanest city in India for the seventh year in a row under the Centre's annual Swachh Survekshan Awards.