New Delhi, Oct. 31: The Indian Institute of Technology (IIT) Kanpur has said the cloud-seeding operation carried out over Delhi this week to trigger artificial rain and knock down toxic air was safe for people and the environment, stressing that the technique uses “minute quantities” of chemicals and cannot, by itself, solve the National Capital Region’s winter pollution crisis.
Prof. Manindra Agrawal, Director, IIT-Kanpur, whose team led the experiment, described cloud seeding as an “SOS measure”, something authorities can deploy only when pollution is very high and the weather offers the right kind of clouds. “The real solution lies in reducing emissions and controlling pollution at the source,” he said, drawing a line between emergency weather modification and long-term air-quality management.
Moisture missing, lessons gained
The Delhi government, working with IIT-Kanpur, ran two trial sorties on Tuesday over Burari, north Karol Bagh and Mayur Vihar. There was no rain. That, Agrawal said, was expected once scientists saw that the clouds over the capital did not carry the minimum 30–50% moisture needed to make seeding effective. “Since that was not available, we decided to wait until conditions improve,” he said, adding that the runs still generated data to fine-tune future operations, chiefly on how much seeding material is needed, what the cloud microphysics looked like over Delhi, and what impact it could have had at ground level.
This distinction is crucial for policymakers: the experiment did not fail because cloud seeding is unsafe; it under-performed because the sky did not cooperate.
‘Too little to harm’
Public health concerns over cloud seeding usually centre on silver iodide, a compound used globally to make cloud droplets coalesce. IIT-Kanpur’s field team sought to defuse precisely that anxiety.
Agrawal said the mixture they used mainly contained common salt and only a small amount of silver iodide. The figure he put out was specific: less than 1 kg of silver iodide over 100 sq. km, under 10 grams per sq. km. “That’s too little to have any harmful effect on humans, animals or vegetation,” he said.
Environmentalists have, in earlier debates, flagged the possibility of silver compounds accumulating in soil and water bodies. Agrawal’s rebuttal on Thursday was unambiguous: at the concentrations used in Delhi, such ecological risks do not arise.
Not a magic wand for Delhi’s smog
The disclosure is also a reality check for residents hoping for an overnight fix to the October-November haze. IIT-Kanpur has said clearly that cloud seeding cannot be the capital’s primary clean-air strategy; at best, it is a tactical tool that can be deployed in a narrow window, when pollution spikes and suitable clouds appear. “It is an SOS measure, something that can be used only when pollution levels are very high and suitable clouds are available,” Agrawal said.
That stance will resonate with air-quality researchers who have long argued that Delhi’s winter crisis is driven by emissions, transport, industry, construction dust, waste burning, and seasonal farm fires and that any weather-based intervention, however sophisticated, can only buy time.
‘Make in India’ layer
What gives this week’s exercise an added policy sheen is that the flares and seeding material were indigenously developed at IIT-Kanpur, which the institute has billed as a technology milestone. The institute had done earlier trials in Kanpur in 2017–18, but this was the first such experiment in the Delhi-NCR region, where both the stakes and the public scrutiny are higher.
An indigenous platform also means future operations, if the Delhi government chooses to repeat them in peak smog weeks, need not depend on expensive foreign kits, making emergency cloud seeding administratively easier.
Delhi’s pollution curve typically worsens in late October and November. Authorities often reach for short-term, visibility-friendly steps, odd-even for cars, bans on construction, water spraying, because those are legible to the public. Cloud seeding sits in the same basket of “seen to be doing something” actions. IIT-Kanpur’s intervention, however, tries to put a scientific guardrail around it: do it only when meteorology allows it, do it with measured quantities, and do not sell it as a cure.
The institute has said the operation was paused, not abandoned and that trials will resume once the cloud moisture meets the 30-50% threshold. That will allow the team to test the same seeding protocol in conditions closer to ideal and compare datasets. The immediate takeaway for Delhi’s pollution managers is that cloud seeding is viable, safe, and locally built, but conditional.
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