New Delhi: Almost coinciding with the Supreme Court's landmark verdict on dealing with air pollution in Delhi, the skies in the city cleared up making way for a sunny Wednesday. Very unusual for the city during the winter, air pollution levels have been falling since December 7—according to both national air quality index (NAQI) monitored by Central Pollution Control Board (CPCB) and the earth sciences ministry (MoES).
Although a Greenpeace report based on the NAQI data indicated at higher monthly averages for November and December than 2014, the sudden improvement in the air quality this month is being felt by everyone. Several people even said they felt relieved and actually enjoyed being outdoors.
Delhi Pollution Control Committee's real-time air quality monitoring on Wednesday revealed that between 10am and 7.30pm, the PM2.5 levels ranged between 150 microgrammes per cubic metres and 39 micrograms per cubic metres. Even at Punjabi Bagh, the levels were between 196 and 70. At RK Puram, the lowest recorded was about 56 microgrammes per cubic metres around 2.30pm. The good news is that similar conditions are likely to persist for three more days followed by a western disturbance, according to Indian Meteorological Department (IMD).
Experts gave two explanations for this sudden improvement. GufranBeig, project director, System of Air Quality and Weather Forecasting and Research (SAFAR) under MoES, felt that there was a reduction in some emission sources. "I don't think the levels have fallen because of meteorological conditions. The reduction in truck numbers may have had an impact. There may have also been a reduction in vehicle numbers possibly due to the air pollution campaign. When temperatures are so low, the air quality doesn't improve like this," he said.
According to AnumitaRoychowdhury, head of Centre for Science and Environment's clean air campaign, if there is a 30% reduction in the truck traffic after the imposition of the environment compensation charge (ECC) by the Supreme Court, it will have an impact on air quality—even if very minor. "Trucks contribute to 30% of particulate matter (PM) emissions from the transport sector. They are a big contributor to Delhi's air pollution problem. But I am sure favourable weather also has a role to play."
The very chilly weather may have acted as a catalyst in bringing down the particulate matter pollution, suggested B P Yadav, director, IMD. "Particles don't remain suspended if it's very cold, so there is less fog. They convert into dew and settle on the ground surface. Also, earlier the winds were easterly which were light and stable but now the winds are from the northwesterly direction and are a bit stronger. The winds may be helping in dispersing the pollutants. You have to also remember that Delhi has started recording minimum temperatures of 5 to 6 degrees Celsius which aids in dew formation," Yadav explained.
