Since the implementation of the Delhi government’s odd-even policy, the first figures collated by the Centre-run Central Pollution Control Board (CPCB) have shown that levels of particulate matter (PM) 2.5 witnessed a drop since January 5 in a majority of air monitoring stations. This comes after an initial spike in PM levels was witnessed during the first few days of the scheme.
Scientists at CPCB said that while weather conditions have helped disperse particulates, especially in the last two days, the drop would not have been possible without controlling of emissions. According to data from CPCB’s eight automatic monitoring stations and seven manual stations, at least half the stations saw a spike in the 24-hour average levels of PM 2.5 from 8 am to 8 pm between December 30 and 31, and January 1 and 2.
At R K Puram for instance, while the average levels measured 292 and 291 micrograms per cubic metre in the last two days of 2015, the levels spiked to 407 on January 1. After it fell to 326 on January 3, it again jumped to 377 on January 4. But between January 5 and 8, the levels dropped from 429 to 259 .
At the IHBAS station in Dilshad Garden, the average levels were 226 micrograms per cubic metre on January 30 which rose to 256 on January 1. But by January 3, it dropped to 247.
At the Punjabi Bagh station, a peak in pollutants was seen on January 7. From 370 micrograms per cubic metre, average levels of PM 2.5 levels spiked by a 100 points. But on January 8, average levels dropped sharply to 272 micrograms per cubic metre.
At Anand Vihar — characterised by high values of particulates as per monitoring by Delhi Pollution Control Committee (DPCC) in the last 10 days — CPCB’s data shows the levels have fluctuated. But between January 6 and 8, a drop was seen in the average levels — from 507 to 366.
Dr Dipankar Saha, additional director and in-charge, Air Laboratory Division at CPCB, said that while meteorological factors have helped improve air quality to some extent, emission control has also helped. “Meteorological factors play a vital role during transition days of any season. This has helped us in the past two days. Had there been increase in emissions, the situation would have been worse. In this experiment, an attempt was made to reduce emissions,” he said.
Meanwhile, DPCC scientists maintained that based on mobile air quality monitoring, the change in air quality has been reflected in the drop in peak levels of particulates. But as per CPCB data, the peak levels remain unchanged. Only the 24-hour average levels have shown a drop. Many stations also showed distinct spikes in peak values.
At Anand Vihar, the peak PM 2.5 values between January 1 and 3 were between 576 and 569 micrograms per cubic metre. Between January 4 and 6, it jumped to between 641 and 633. At Punjabi Bagh, the peaks spiked from 406 to 496 during the same period.