With a dip in temperature, the air quality index (AQI) of many cities in Bihar turned ‘poor’ on Sunday.

Bhagalpur recorded ‘very poor’ air quality with an AQI of 324, while Arrah, Sasaram, Saharsa, Araria, Rajgir and Patna recorded ‘poor’ air quality.

The Central Pollution Control Board (CPCB) ‘Air Quality Index’ (AQI) bulletin of December 30 till 4 pm of 238 cities stated that Bhagalpur recorded an AQI of 324 (very poor level). Six other Bihar districts where the AQI was in the poor category on December 30 were Arrah (292), Sasaram (285), Saharsa (262), Araria (259), Rajgir (245) and Patna (208).

The AQI is an assessment of the air quality taking into account eight pollutants - PM 2.5 (particulate matter less than 2.5 microns), PM 10 (particulate matter less than 10 microns), nitrogen oxides, sulphur dioxide, ozone, carbon monoxide, ammonia and lead.

An AQI between zero and 50 is considered “good” (minimal impact), 51 and 100 “satisfactory” (minor breathing discomfort to sensitive people), 101 and 200 “moderate” (breathing discomfort to people with lungs, asthma and heart diseases), 201 and 300 “poor” (breathing discomfort to most people on prolonged exposure), 301 and 400 “very poor” (respiratory illness on prolonged exposure), and 401 and 500 “severe” (affects healthy people and seriously impacts those with existing diseases).

Commenting on deteriorating air quality in the state, Bihar State Pollution Control Board (BSPCB) Chairman Devendra Kumar Shukla told PTI on Sunday, “It is true that the air quality has deteriorated in certain cities in the state. It is because of climatic conditions…. This deterioration in air quality is primarily due to northwesterly winds carrying pollutants from stubble fires, coupled with calmer wind conditions and dipping temperatures”.