NEW DELHI: Delhi’s air quality improved slightly on Monday due to favourable wind speed while it improved drastically to reach ‘poor’ level from ‘severe’ in other cities of the National Capital Region.
The city’s 24-hour average air quality index (AQI) was 253 on Monday. It was 396 on Sunday, 337 on Saturday, 357 on Friday, 423 on Thursday, 433 on Wednesday and 418 on Tuesday. The average 24-hour AQI at 4 pm on Monday was 256 in Ghaziabad, 237 in Greater Noida, 225 in Noida, 296 in Faridabad and 226 in Gurugram, according to CPCB’s Sameer app. Presence of pollutants PM 2.5 and PM 10 also remained high in the five immediate neighbours of Delhi.
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. The CPCB states that an AQI in the ‘poor’ category may cause breathing discomfort to people on prolonged exposure. The average AQI on Sunday was 407 in Ghaziabad, 418 in Greater Noida, 405 in Noida, 404 in Faridabad and 359 in Gurugram. The AQI for each city is based on the average value of all stations there. Noida, Faridabad, Ghaziabad have four stations each, while Gurgaon has three and Greater Noida two, according to the app.
Officials at the India Meteorological Department (IMD) said favourable wind speed, up to 15 kmph, aided in the dispersion of pollutants. On Sunday night, Delhi’s air quality had entered the “severe” category briefly as’light rainfall in neighbouring areas increased moisture content in the air. “Water droplets suspended in the air and made pollutants heavier which do not get dispersed easily even with a moderate wind speed,” an IMD official said.
With PTI inputs