New Delhi: Delhi’s air quality turned ‘severe’ on Tuesday for the first time this season with stubble burning intensifying in neighbouring states, authorities said. The overall Air Quality Index (AQI) at 3 pm was 401, falling in the ‘severe’ category, the highest this season, Central Pollution Control Board officials said. An AQI between 0 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’.
The Centre-run System of Air Quality Forecasting And Research (SAFAR) attributed the spike to “heavy stubble burning in the last 24 hours and calm winds”. About 28 per cent of pollution by PM2.5 (presence of particles in the air with a diameter of less than 2.5 micrometres) on Tuesday was caused due to regional factors like stubble burning, SAFAR officials said. The Indian Institute of Tropical Meteorology (IITM) also spotted a large number of biomass fire spots through satellite imageries in neighbouring states of Delhi.