‘Very poor’ AQI streak 20 days and counting

DElhi’s broadcast character remained in the ‘ real poor’ category on tues, extending a toxic run to 20 consecutive days and putting the Capital on course to record its second-longest pollution siege if similar air pollution persists till the weekend, as has been predicted.With 353 at 4pm on Tuesday, the Air Quality Index (AQI) has now been at 300 or above since November 6, the fifth-longest such streak recorded since the Central Pollution Control Board (CPCB) launched the index in April 2015. Forecasts show meteorological conditions are unlikely to improve before November 28, which would push the streak to 23 days — tying for the second-worst on record.The longest streak came last year, when Delhi logged 32 consecutive days of ‘very poor’ or worse air between October 30 and November 30, including a peak of 494 (severe) on November 18.The current stretch has included three severe air days between November 11-13, data shows. The streak began in early November as the winter pollution season took hold, but unlike previous years, farm fires have contributed far less to the crisis.The Decision Support System recorded a peak farm fire contribution of 22.4% on November 12, significantly lower than historical patterns. Last year, stubble burning accounted for 35.1% of Delhi’s pollution on November 1. The contribution peaked at 35% on November 3 in both 2023 and 2022, while reaching 48% on November 6 in 2021.By Tuesday, farm fire contribution had dropped to just 1.54%.Sunil Dahiya, founder and lead analyst at Envirocatalysts, said the prolonged streak exposes systemic failures in pollution control. “This long and consistent streak shows how the reactionary measures under the Graded Response Action Plan are not being implemented on the ground, leading to no emission load reduction,” he said.“The data also shows this has been happening for the past several years, so our baseload emissions have simply not come down. Whenever meteorological conditions turn unfavourable, there is stagnation and accumulation of pollutants. This necessitates reducing the overall PM2.5 load by tackling sources.”Dipankar Saha, former head of CPCB’s air laboratory, said the persistence of high pollution during predictable winter conditions points to inadequate implementation. “We know invariably, meteorological conditions will turn unfavourable in the winter months. In such a situation, we need stringent measures to be put in place and better on-ground implementation of measures, even if it inconveniences people,” he said.“This also shows despite efforts and policies to control pollution, our baseload is still very high and more action is needed moving forward.”The CPCB classifies air as ‘good’ when AQI is 50 or lower; ‘satisfactory’ between 51 and 100; ‘moderate’ between 101 and 200; ‘poor’ between 201 and 300; ‘very poor’ between 301 and 400; and ‘severe’ when it exceeds 400.The persistence of ‘very poor’ air has become a defining characteristic of this winter season. Experts attribute the sustained pollution to largely calm winds and frequent changes in wind direction, preventing dispersal of pollutants.“Over the last fortnight in particular, we have had variable light winds. Though it picks up marginally during the day between 8-10 km/hr, they have largely remained calm at night, which is when temperature is low. A frequent change of wind direction is also leading to accumulation of pollutants,” said Mahesh Palawat, vice president at Skymet.Palawat said conditions are unlikely to improve in the coming days, meaning an immediate reprieve is unlikely. The India Meteorological Department has said a western disturbance is not expected to impact northwest India until at least the end of the month. Forecasts show winds may marginally improve from November 28, touching 10-15 km/hr during the day, but are likely to become calm again at night.The Centre’s Air Quality Early Warning System offered even sparser hope for immediate relief. “Delhi’s air quality is likely to be in the ‘very poor’ category from November 26 till 28. The outlook for the subsequent six days shows the air quality is likely to be between ‘severe’ to ‘very poor’ category,” the system’s daily bulletin stated on Tuesday.The second-longest streak on record—23 days—occurred between December 17, 2018 and January 8, 2019. Delhi has logged two 21-day streaks: November 2-22, 2022 and January 11-31, 2024.The latest Global Burden of Disease (GBD) 2023 data has continued to flag high air pollution levels as a leading global health risk, stating it contributed to an estimated 7.9 million deaths worldwide in 2023 and an annual global economic cost of approximately $6 trillion due to health damages.The economic impact stemmed from lost productivity, increased health care costs, and premature deaths, particularly in countries impacted by high pollution levels. Delhi-NCR has consistently ranks among the world’s most polluted hotspots.