Spike in Delhi pollution as winter spiral begins
The air quality in Delhi plummeted to its worst levels since January as smoke from smouldering paddy fields in Punjab and Haryana drifted in, marking the beginning of what has been an annual environmental blight that is only predicted to worsen, with more farm fires likely and unhelpful meteorological conditions predicted to persist. The air quality index (AQI) slumped from an uncharacteristically clean 271 on Wednesday to 354 on Thursday, according to the 4pm bulletins released on both days by the Central Pollution Control Board. An AQI above 300 is considered “very poor” – the second worst band on the AQI scale. At least two regions in the city, Anand Vihar and Ashok Vihar, had an AQI above 400, which lies in the worst “severe” band. “Wind speeds have dropped significantly from October 26 onwards and we are seeing calm wind conditions at night time. Delhi saw calm wind conditions for nearly seven hours between 4.30am to 11.30am on Thursday, with this spell playing a significant role in accumulation of pollutants,” said RK Jenamani, scientist at IMD. This was Delhi’s highest AQI in over 10 months; on January 21, it was 365. Forecasts show similar calm conditions are expected to prevail until the end of the month now, largely keeping Delhi’s air quality in the “very poor” category. According to officials in Punjab, roughly about 8,100 farm fires have been recorded till now – 20% higher than what was recorded until October 27 last year, indicating a failure on the part of the state government to stem the tide – and a sharper spike is expected in the coming weeks since farmers in the south Malwa belt of the state, where farm fires are widespread, are only now beginning to clear their fields. Major rice-producing districts such Bathinda, Moga, Mansa, Muktsar and Faridkot have recorded only 20-40% harvesting, said an official of the state agriculture department on Thursday. In the last four of the five years, the number of fires in south Malwa accounted for close to 50% of the fires recorded in Punjab. Behind the deterioration in Delhi’s air quality was the perfect storm of conditions: the direction of winds changed to northwesterly that fed in a stream of smoke from fires, the number of fires itself spiked in recent days, local winds weakened that help blow away dust and tailpipe gases died down, and the temperature dipped, creating an “inversion” effect that causes pollutants to settle closer to the ground, instead of being dispersed higher into the sky. Anumita Roychowdhury, executive director, research and advocacy at the Centre for Science and Environment (CSE) said when the farm fire impact begins to be felt more strongly, “the AQI could considerably worsen. Till now, Delhi was seeing good wind speed, which was controlling the pollution levels. As soon as winds become calm, local emissions are enough to cause the AQI to reach ‘very poor’,” she said.
