The air quality in the national capital remained in the "very poor" category, with the overall Air Quality Index (AQI) recorded at 381..Thirteen Delhi monitoring stations reported severe air quality, while 25 recorded very poor levels, according to CPCB's Sameer app..Pollution levels in the Yamuna have worsened since March this year, primarily by untreated sewage and industrial effluents..For the first time in India, hundreds of citizens gathered on Sunday to protest the national capital’s dangerously polluted air..Delhi Police arrested 22 for blocking roads, using chilli spray on officers, during an air quality protest at India Gate's C-Hexagon..The air pollution levels across North India are higher than the national average, according to Centre for Research on Energy and Clean Air (CREA)..Delhi worst in PM2.5 pollution; 447 districts breach national air quality norm: Report.Follow The New Indian Express channel on WhatsApp Download the TNIE app to stay with us and follow the latest