India has tested cloud seeding over its smog-filled capital for the first time, spraying a chemical from a plane to encourage rain and remove deadly particles from the air.
Cloud seeding involves using planes to spray salt or other chemicals into clouds to cause rain.
New Delhi city authorities, in collaboration with the Indian Institute of Technology Kanpur, launched a test on Thursday afternoon aboard a Cessna light aircraft over the Burari region, north of the city.
“A test flight was conducted… during which cloud seeding flares were fired,” Delhi Minister Manjinder Singh Sirsa said in a statement on Thursday.
“This flight was the test flight to verify cloud seeding capabilities, aircraft readiness and endurance, evaluation of equipment and flare capabilities for cloud seeding, as well as coordination between all agencies involved.”
This precedes the planned rollout of the program. Delhi Chief Minister Rekha Gupta said that “if conditions remain favourable, Delhi will experience its first artificial rain on October 29.”
Read: Indian Diwali smog chokes Punjab
It was unclear exactly what chemical was used in the test to encourage rain.
New Delhi and its vast metropolitan area of 30 million people are regularly ranked among the world’s most polluted capitals, with acrid smog blanketing the horizon every winter.
Cooler air traps pollutants close to the ground, creating a deadly mix of emissions from crop burning, factories and heavy traffic.
Levels of PM2.5 – carcinogenic microparticles small enough to enter the bloodstream – sometimes reach up to 60 times the UN daily health limits.
Pollution increased this week after days of fireworks to mark Diwali, the Hindu festival of lights, sending PM2.5 levels soaring to more than 56 times the limit.
This came after the Supreme Court this month relaxed a blanket ban on fireworks to allow the use of less polluting “green” crackers, developed to reduce particulate emissions. As of dawn on Thursday, PM 2.5 levels were 154 micrograms per cubic meter in parts of New Delhi, according to monitoring body IQAir, just over 10 times the World Health Organization limits.
A study revealed in September that the noxious air is even blackening Delhi’s iconic 17th-century Red Fort.
Learn more: The capital adopts a new strategy to fight smog
Scientists have warned that the UNESCO World Heritage site is gradually being disfigured by a black crust, according to a study published in the journal Heritage by a joint team of Indian and Italian researchers.
Invented in the 1940s, the system has been seeding clouds for decades to alleviate drought, fight wildfires and even disperse fog at airports. China used it in 2008 to try to stop rain from falling on the Olympic stadium in Beijing. But research on the effects of cloud seeding on neighboring regions is mixed — and some evidence suggests it doesn’t work very well, even in the target area.
