NEWS

Could Cloud Seeding Be The Best Answer To Delhi's Pollution Problem?

Delhi’s geography is the main reason why pollutants get trapped.

07/11/2016 7:58 AM IST | Updated 07/11/2016 9:24 AM IST
NEW! HIGHLIGHT AND SHARE
Highlight text to share via Facebook and Twitter
Hindustan Times via Getty Images
People wear pollution masks during the protest march for 'Your Right To Breathe' at Jantar Mantar, on November 6, 2016 in New Delhi, India.

During the monsoons, pollution meters show Delhi's air falling to safe levels. What happens in the winters is that that there's no water to wash away Delhi's dust and other pollutants. This is why unacceptably high smog occurs in the three months of November, December and January.

Experts are unable to agree on what causes how much air pollution in Delhi. Is road dust the main cause or is it cars or trucks? What the experts do agree on is geography.

Delhi's location is the reason why the movement of winds often traps air in Delhi. As temperatures drop, unmoving air doesn't let dust and other pollutants carried out of the city, the high pressure haze making use breathe these pollutants.

Hindustan Times via Getty Images
People wear pollution masks during the protest march for 'Your Right To Breathe' at Jantar Mantar, on November 6, 2016 in New Delhi, India.

Dr MP George, a scientist with the Delhi Pollution Control Committee, believes that thanks to geographical reasons, the best we could do is bring down air pollution to moderately high levels.

This is not to say the pollution isn't man-made. It's just that trapped air brings pollutants from neighbouring areas but doesn't take them away, in these three months.

According to Dr Prashant Kumar, co-author of a study on Delhi pollution last year, "The geography of Delhi results in the advection of air, or large-scale movement in the atmosphere, into the city from the surrounding areas, which can sometimes be significantly more polluted than the city centre itself. As a land-locked megacity, there are limited avenues for the flushing of polluted air out of the city, or its replacement with air from relatively unpolluted marine regions, which means that atmospheric transport from all directions, is likely to add to inner-city pollution."

ALSO READ: Delhi CM Arvind Kejriwal Announces Emergency Measures To Curb Smog

ALSO READ: Shifting Blame, Centre Calls Delhi's Garbage The Reason Behind Record Smog

ALSO READ: Delhi Pollution An 'Emergency', Says Environment Minister

This is not to say the pollution isn't man-made. It's just that trapped air brings pollutants from neighbouring areas but doesn't take them away, in these three months.

Incidentally, Beijing also suffers high pollution due to a geographical disadvantage. Like Beijing, Delhi must consider artificial rain to deal with the problem, as chief minister Arvind Kejriwal suggested yesterday.

When moist clouds come in contact with silver iodide or other such chemicals, they dissipate into rain. The chemicals could be fired into the clouds from the ground or, more effectively, dropped over the clouds from aircrafts. Called cloud seeding, this method of creating artificial rain has been around for decades.

This can work only if there are moist clouds in the atmosphere in the first place. Beijing has found the method to be so effective it uses it whenever there are international conferences or national days to be celebrated in Beijing. It was used, most famously, in the 2008 Beijing Olympics to bring about clear blue skies, not only to wash smog away but also to make sure it doesn't rain during the open-air ceremony.

Cloud seeding has been found to be environmentally safe. China has a full department of weather modification that has been cloud seeding extensively. There are those who think the Chinese government exaggerates claims of cloud seeding's success, but there is growing scientific evidence that it works.

Scientists in Pune are studying the feasibility of cloud seeding to address smog in Delhi. But India has done cloud seeding in the past, to help alleviate drought. As recently as 2003-04, an American company was hired for two rounds of 240 days of cloud-seeding in drought-struck Maharashtra. Tamil Nadu carried out cloud seeding to address drought for many years in the 1980s and early '90s.

Cloud seeding can't create clouds, and can't be a large-scale, long-term solution for any problem, smog or drought. To the extent it is possible, it can help. Falling droplets of water can clean the atmosphere by coagulating with the fine particles in the air, as an MIT study found.

Some still say rain may not wash away smog, because PM 2.5 consists of particulates too minute, but it is definitely worth experimenting. After all, we don't experience such smog during the monsoon months. Short of rain, spraying the streets with water should also help stop the movement of pollution particulates in the air.

There may be other problems peculiar to Delhi with artificial rain. It may artificially bring down temperatures even further in a city where the homeless die of cold and central heating is not a common feature in homes. Just a bit of rain clogs Delhi's sewage system, brings traffic to a halt.

More On This Topic