10 worst polluted cities in country from Bihar

PATNA: All the top ten cities with worst air quality in the country on Sunday were from Bihar. Patnaites breathed the worst air of the season as its air quality index (AQI) plunged to 402 in the 'severe' category due to poor dispersion of pollutants owing to weak winds, moisture incursion, drop in temperature, road dust or dust from construction sites and vehicular emission.
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According to the Central Pollution Control Board (CPCB), Patna AQI was worse than 367 (very poor) a day before.

Begusarai recorded the worst AQI level at 474, closely followed by Darbhanga (446), Katihar (442), Siwan (429), Purnia (404), Saharsa (404), Patna (402) and Samastipur (399). Greater Noida and Ara had AQI at 398 and Bhagalpur at 388 while Delhi had it at 353.
As per the CPCB, severe AQI level can affect healthy people and seriously impact those with existing diseases.
Patna air quality turns 'severe'
The AQI was in 'very poor' category also at Muzaffarpur (383), Aurangabad (348), Munger (344), Sasaram (341), Bettiah (334), Motihari (322), Hajipur (312), Araria (305) and Gaya (301). The very poor level of pollutants can cause respiratory illnesses on prolonged exposure.
Pradhan Parth Sarthi, president of Indian Meteorological Society (Patna Chapter) and steering committee member of Bihar State Action Plan of Climate Change, attributed three metrological factors to the rise in air pollution - temperature inversion that exists during the winter time, absence of windy conditions or calm wind and partly cloudy sky. "All these factors also determine the level of concentration of PM10 (particulate matter less than 10 micron) and PM 2.5 (particulate matter less than 2.5 micron)," he said.
He said in eastern UP and Bihar, the temperature remains very strong in winter as it is closer to the foothills of the Himalaya. Temperature inversion is a meteorological phenomenon that develops when cool air is trapped at the ground under a layer of warm air. The average concentrations of PM 2.5 in the city stood at 199 micrograms per cubic metre (g/m3).