Delhi’s air saw a marked decrease in the volume of pollutants due to strong wind movement, a day after the city’s air quality moved into the ‘severe’ zone for the first time this year.
‘Severe’ pollution levels seriously impacts those with existing respiratory or cardiovascular diseases, while ‘very poor’ AQI comes with the warning that people may develop respiratory illness on prolonged exposure.
The Central Pollution Control Board (CPCB), which had attributed Friday’s high pollution levels to calm wind movement and a low mixing height (where air and suspended particles mix), said the situation will improve further if favourable conditions prevail. “The wind speed is expected to pick up and reach up to nine km/hour, which is adequate for the dispersion of suspended particulates. Yesterday and the day before, wind speed and mixing height were extremely low, which led to rapid build up of pollutants near the surface,” said Dipankar Saha, CPCB’s air lab head.
Six of the eight stations maintained by SAFAR (System of Air Quality Forecasting and Research), had air quality index (AQI) in the ‘very poor’ category, a shade better than ‘severe’. Among the stations maintained by the CPCB, nine of 17 were in the ‘very poor’ category, while the rest recorded ‘severe’ air quality. At 12 pm on Saturday, the 24-hour rolling average of PM 2.5 and PM10 ultra-fine particulates were 206 and 357 microgram per cubic metre (µg/m3) respectively, as against Friday’s 407 and 595. Their 24-hour safe standards are 60 and 100 µg/m3.
The CPCB had, on Friday, recorded an air quality index of 403 µg/m3 in Delhi, 402 µg/m3 in Noida and 412 µg/m3 in Ghaziabad, all in the severe zone or the most polluted category. Though pollution levels in the city breached emergency levels on Diwali and the day after, pollution monitoring agencies concurred that the city was relatively better off compared to last year’s post-Diwali period.
(With PTI inputs)