Delhi’s air quality recorded a marginal improvement on Saturday morning due to favourable wind speed but remained in the “poor” category. Similar situation was witnessed in NCR cities of Noida, Greater Noida, Ghaziabad, Gurgaon and Faridabad.
Government agencies said the air quality index (AQI) was likely to improve to the “moderate” category later in the day.
Delhi’s AQI was 263 at 9 am. The 24-hour average AQI was 296 on Friday. It was 283 on Thursday and 211 on Wednesday.
Similarly, the average 24-hour AQI at 4 pm on Saturday was 256 in Gurgaon, 246 in Faridabad, 238 in Ghaziabad, 231 in Noida and 228 in Greater Noida, according to CPCB’s Sameer app.
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”.
Calm winds and low temperatures trap pollutants close to the ground, while favourable wind speed helps in their dispersion. Delhi’s ventilation index — a product of mixing depth and average wind speed — was around 13,000 square metre per second on Saturday and is likely to be 6,000 square metre per second on Sunday.
