The downward spiral of deteriorating air quality has continued across the National Capital Region as air quality in part of North India has now dropped to ‘severe’ category from ‘very poor’. Air pollution breached ‘severe’ levels for the first time this season in Delhi and it marks a sharp deterioration caused by a double whammy of toxic fumes left over from illegal Diwali fireworks and stubble burning in neighbouring states.
Two days after Diwali, the Central Pollution Control Board (CPCB) said in their bulletin that Delhi’s overall air quality index (AQI) was 400 in contrast to 368 on October 28. 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’. By the night of October 29, the AQI of the National Capital climbed to 421 as lower temperatures led heavy pollutants to sink closer to the ground. Pollution levels in Ghaziabad, Noida and Greater Noida are much worse as their AQI levels were 446, 439 and 428 respectively. Further, Gurugram and Faridabad were in the ‘very poor’ category at 368 and 387 respectively.
Experts and scientists said that the post-Diwali air on October 28 was the cleanest in three years but the pollution remained in the ‘very poor’ category, with the PM2.5 level rising to 18 times the safe limit. According to scientists at pollution forecasting agencies, the air is likely to worsen over the coming days since a north-westerly wind is bringing with it smoke from Punjab and Haryana, where crop stubble burning is at its peak this week.