Kolkata: In Kolkata, on Tuesday at 6 AM, the Air Quality Index (AQI) was 193, which is considered 'moderate' air quality, according to aqicn.org. The city's air quality became 'poor' on Monday when the overall AQI reached 206 (PM2.5 level), as reported by the US Mission India's NowCast Air Quality Index., Kolkata News, Times Now