The overall air quality index level stood in the 'moderate' category as of 6:30 am on Friday. An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'., Delhi News, Times Now