Meghalaya's Byrnihat was the most polluted city in India in January this year with a monthly average PM2.5 concentration of 214 µg/m³, according to a Centre for Research on Energy and Clean Air (CREA) report. It was followed by Delhi, with a monthly average PM2.5 of 165 µg/m³, and Bihar's Hajipur, with a monthly average PM2.5 of 121 µg/m³.