Delhi’s skyline, once a familiar sight of vibrant city life, has been shrouded in a persistent, toxic haze every autumn for years. This October, with the air quality index (AQI) soaring above 300—well into the ‘very poor’ category—residents and officials alike were desperate for a solution. The latest hope? Cloud seeding, a technology that’s as much the stuff of science fiction as it is of scientific controversy.
On October 28, 2025, the Delhi government, in collaboration with the Indian Institute of Technology (IIT) Kanpur, launched an ambitious cloud seeding experiment. The plan was simple in theory: disperse a carefully crafted mix of chemicals into the clouds, coaxing them to release rain that could wash away the city’s airborne pollutants. With a budget of Rs 3.21 crore earmarked for five such trials, the stakes were high and the expectations even higher.
But reality, as it often does, proved more complicated. According to The Economic Times, three rounds of cloud seeding had been conducted by late Tuesday, October 28. A Cessna-206H aircraft, loaded with eight flares per sortie, crisscrossed the skies between Khekra and Burari, covering a swath 25 nautical miles long and 4 nautical miles wide. The flights, which began at 12:13 pm and again at 3:45 pm, dispersed a mix of silver iodide and other salts designed to nudge the clouds into letting loose their precious cargo.
Yet, as IIT Kanpur confirmed, no rain fell in Delhi itself by 9 pm that night. Neighboring areas like Noida and Greater Noida recorded only negligible rainfall—0.1 mm and 0.2 mm, respectively, according to a private weather app cited by The Times of India. The operation, despite its scale and cost, failed to deliver the much-anticipated showers over the capital.
The science behind cloud seeding is intriguing but fraught with uncertainty. As The Indian Express explained, the technique involves dispersing substances—typically silver iodide or sodium chloride—into moisture-laden clouds to encourage precipitation. While it’s been deployed in places like China, the United States, and the UAE to address drought, its use in combating air pollution remains rare and scientifically inconclusive. Its effectiveness, experts say, hinges on the right atmospheric conditions: sufficient cloud cover, adequate humidity, and favorable winds.
Delhi’s trials, unfortunately, were hampered by low moisture levels. IIT Kanpur noted that the humidity in targeted clouds hovered between 10 and 20 percent—far from ideal for successful seeding. "The process is highly dependent on the right atmospheric conditions," the institute stated. Without enough moisture, even the best-engineered interventions can fall flat.
Still, the experiment wasn’t entirely without effect. Monitoring stations across Delhi captured real-time changes in particulate matter and moisture levels. IIT Kanpur reported a measurable reduction of 6 to 10 percent in PM2.5 and PM10 concentrations during the trials. For instance, PM2.5 levels dropped from 221-230 micrograms per cubic meter to 203-207 at locations like Mayur Vihar, Karol Bagh, and Burari. PM10 levels also saw a decrease, from around 206-209 to 163-177 micrograms per cubic meter.
How significant are these numbers? That depends on whom you ask. Some, like Delhi’s environment minister Manjinder Singh Sirsa, hailed the operation as a “huge step to mitigate pollution.” Sirsa emphasized the government’s commitment to scientific solutions, crediting the support of Chief Minister Rekha Gupta and Prime Minister Narendra Modi for enabling bold climate action. The government, he said, is also pursuing other measures, such as converting the city’s entire bus fleet to electric vehicles, in its multi-pronged approach to cleaner air.
Yet, skepticism abounds among scientists and environmentalists. Mukesh Khare, professor emeritus at IIT Delhi, cautioned that without actual rainfall, the benefits of cloud seeding for air quality remain questionable. "Natural rain can reduce PM2.5 concentration depending on the raindrop size, their density and fall velocity. However, clouds are generally devoid of humidity during winters in Delhi," Khare explained to The Times of India. He suggested that the observed reductions in particulate matter might be due to other factors, such as the temporary increase in humidity making particles heavier, rather than the settling effect of rain itself.
The broader context, as highlighted by The Indian Express, is that Delhi’s pollution problem is neither new nor mysterious. Decades of research have pinpointed its sources: agricultural residue burning in Punjab and Haryana, vehicular emissions, industrial activity, and dust from construction. Each autumn, meteorological conditions—specifically, temperature inversion—trap these pollutants close to the ground, turning the city into a gas chamber.
Despite this well-established science, policy responses often veer toward the symbolic or the short-term. Over the years, Delhi has experimented with smog towers, anti-smog guns, odd-even vehicle schemes, and now, artificial rain. These emergency measures, while grabbing headlines, rarely address the systemic roots of the crisis.
What’s needed, experts argue, is not more high-visibility experiments but sustained, science-based governance. Long-term solutions include strict enforcement of emission norms, a transition to cleaner fuels and technologies, improved public transport, better waste management, and—crucially—regional coordination, especially on crop residue burning. Institutions like the Commission for Air Quality Management (CAQM) must be empowered to drive transparent, data-driven decisions across state lines.
Technology can help, but only as part of a larger strategy. Innovations like low-cost air quality sensors, AI-driven emissions monitoring, and satellite-based forecasting offer valuable tools, but their impact depends on integration into a robust governance framework. As the Indian Express opined, “Delhi’s fight against air pollution is as much about coordinated governance and implementation as it is about science.”
For now, Delhi’s cloud seeding experiment stands as both a testament to scientific ambition and a sobering reminder of the city’s complex air quality challenge. More trials are planned, with IIT Kanpur pledging to conduct up to nine within the current budget. But unless these efforts are paired with systemic reforms and regional cooperation, even the most advanced technologies will offer only fleeting relief.
Delhi’s residents, meanwhile, continue to hope for clear skies—not as a result of emergency interventions, but as a sustained right grounded in sound policy and collective action.
