Delhi's air quality showed an unusual improvement on Sunday, thanks to increased wind speed, favourable for dispersion of pollutants. For the second consecutive day, the air quality index in the national capital remained in the 'poor category'.
The overall air quality index (AQI) was recorded at 262, which falls in the "poor" category, according to the Centre-run System of Air Quality and Weather Forecasting (SAFAR).
Delhi Pollution: Slight improvement in air quality; task force recommends stricter action in 'hotspots'
Six areas in the national capital recorded "very poor" quality air while 21 areas recorded "poor" air quality, according Central Pollution Control Board (CPCB) data.
The PM2.5 level (particles in the air with a diameter of less than 2.5 micrometres) was recorded at 124 and the PM10 level was recorded at 250, it said.
Ghaziabad, Greater Noida and Noida recorded "poor" air quality while Faridabad recorded "moderate" air quality, the CPCB data said.
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".
According to the SAFAR, the improvement in air quality is "unusual" for this time of the year.
"The major role is being played by late night faster wind speed which otherwise remains calm. However, the air quality is expected to keep oscillating between 'poor' and 'very poor' for the next three days," the SAFAR said.
Meanwhile, environment experts have said inducing artificial rain by cloud-seeding to wash away pollutants in Delhi may bring relief but only for a short duration, and the government should take systematic and coordinated actions to reduce air pollution at source.
They said measures to bring down air pollution levels should be undertaken without having a second thought, but there is also a need for a long-term and focused approach to address this problem.
With air pollution levels in Delhi often reaching alarming levels during winters, authorities have said they might induce artificial rain by cloud-seeding to wash away pollutants in the air.
They, however, did not say when do they plan to do that.
Environment experts said policymakers should pay attention to an aggressive shift away from polluting fuels and also focus on strict implementation of rules and regulations to control air pollution in Delhi.
"Cloud-seeding might give relief for a short span of time from air pollution by virtue of washing down the pollutants from air but for how long? It is nowhere near to a solution to pollution," Greenpeace India's senior campaigner Sunil Dahiya said.
"Once the pollutants are released into the air trapping them is going to be an energy-intensive process and can not be done at a largescale over sustained, longer time periods," he said.
Cloud-seeding is the process of combining different kinds of chemical agents, including silver iodide, dry ice and even table salt, in clouds to thicken them and increase the chance of rainfall.
In 2016, the government tried to explore the possibility of cloud-seeding for artificial rain but the plan never worked out.
"If the government is serious about reducing pollution levels and make the air breathable, systematic and coordinated actions to reduce pollution at source by adopting efficient pollution control technologies and systematically eliminating polluting sources is the only way.
"Strict implementation of rules and regulation to control pollution with aggressive shift away from polluting fuels of past should get the priority and attention of our policy makers," Dahiya said.
He said the Delhi government and the Union Environment Ministry have to be serious about coming out with a time-bound and target-oriented National Clean Air Action Plan for "absolute" pollution level reduction.
"We are in the midst of a health emergency and without any further delay we have to get on to executing the plan to control multiple sources attributing to air pollution. We sincerely hope that India will keep its commitment made in WHO’s air pollution and health conference to notify the NCAP by December 2018," Dahiya said.
Another expert maintained that since Delhi reels under severe pollution levels during winters, any measure which brings the levels down must be done "without second thoughts".
Aishwarya Sudhir, senior researcher, Climate Trends, said, "Delhi is still reeling under severe pollution levels, any measure that can bring down the pollution levels must be done without second thoughts.
"However, the larger question remains — the need for long-term, focused approach to address the problem at it's source, be it transport or crop burning," Sudhir said.