Cloud seeding not feasible, says Central Pollution Control Board amid Delhi pollution crisis

New Delhi: The Central Pollution Control Board has said the feasibility of cloud seeding as an emergency measure to battle winter pollution in northern India will be limited, citing insufficient moisture and reliance on pre-existing clouds, an RTI query has revealed.

The CPCB shared its observations on a cloud seeding proposal by IIT Kanpur, which aims to combat Delhi's severe air pollution crisis through artificial rainfall.

The information was shared in response to a Right to Information query filed by activist Amit Gupta on October 24.

According to the CPCB, cloud seeding faces significant challenges due to insufficient moisture in the air and the dependency on pre-existing clouds influenced by Western Disturbances.

"As per IIT Kanpur (proponent), the mandatory requirement of successful cloud seeding is the availability of appropriate clouds with enough moisture content (clouds having 50 per cent or higher moisture content).

"In northern India, winter clouds are often influenced by Western Disturbances, and the moisture content in the air remains low, limiting the scope of successful operations," the CPCB stated in its reply.

The board's comment comes against the backdrop of the Delhi government seeking emergency measures to combat a sharp rise in the city's pollution.

Reportedly, Delhi Environment Minister Gopal Rai has written to his Union counterpart Bhupender Yadav four times, urging the Centre to consider cloud seeding as a potential solution and convene a meeting on the matter.

Meanwhile, CPCB said the estimated cost of the proposed experiment will be approximately Rs 3 crore. The proposal includes a minimum coverage area of 100 sqkm and involves five sorties (cloud seeding attempts).

As part of the proposal, a presentation was made by Dr Manindra Agrawal and his team from IIT Kanpur to the Delhi government on November 8, 2023.

The presentation outlined the involvement of 12 key agencies, including Defence, Home, and Environment.

IIT Kanpur conducted cloud seeding trials during the summer of 2017, reportedly achieving successful precipitation in six out of seven attempts.

The trials primarily aimed at developing a cost-effective strategy for cloud seeding by optimising both seeding agents and flying platforms. While the experiments resulted in successful precipitation, the type and intensity of rainfall remained difficult to control.

The proposed trials in Delhi aim to build on the findings of those trials.

A recent report said that light-intensity rains (2.5-15.5 mm) in Delhi on three days in November last year brought the PM2.5 concentrations from 315 micrograms per cubic metre air to 95 micrograms per cubic metre air during the period.

PM10 levels too reduced from 501 micrograms per cubic metre air to 167 micrograms per cubic metre air over the same period.

All the same, the cloud seeding proposal has sparked mixed reactions among environmental activists.

Amit Gupta, who filed the RTI, urged the government to conduct the trials without delay.

"It's high time we tried this measure because nothing else seems to be working for Delhi's pollution crisis. If IIT Kanpur has achieved success with cloud seeding, our government should too. The central government must provide the necessary clearances for the experiment," he said.

On the other hand, environmentalist Verhaen Khanna dismissed the experiment as an ineffective and potentially harmful solution.

"The better option is to stop producing pollution in the first place and prevent tree-cutting in Delhi. Today, hundreds of trees are being felled, which would otherwise help reduce pollution," he said.

Khanna also raised concerns about the use of silver iodide, the chemical used in cloud seeding, warning of its harmful effects on humans.

"Whoever is promoting cloud seeding should first make a video of themselves consuming silver iodide – the same chemical that will be sprayed into clouds. This chemical could cause nausea, diarrhoea, skin burns, and even cancer, especially in children and senior citizens exposed to it through food, skin, or the environment," he said.