As it grapples with toxic smog, the Delhi government has turned to an unusual solution to tackle its air pollution problem.
Water mist cannons, or "anti-smog guns," have been tested in Anand Vihar, an area in northern Delhi that's one of the Indian capital's most polluted regions.
A machine sprays atomized water up to 230 feet into the air
It aims to merge with dust particles and replicate effects of rain to lower pollution level
A machine is connected to a water tank and mounted on a flatbed truck and sprays atomized water -- in which liquid is broken up into smaller droplets -- up to 230 feet into the air.
The idea is that the droplets merge with dust particles, replicating the effect of rain. Rain lowers levels of air pollution by bringing particulates in pollution down to the ground.
In 2015, use of the machines was widely reported in China, and they could soon become a familiar site on the streets of Delhi.
A daylong trial was carried out Wednesday by the Department of Environment and the Delhi Pollution Control Committee, part of the city's governing Aam Aadmi Party.
Delhi Environment Minister Imran Hussain, who witnessed the tests, told CNN affiliate News 18 that "the idea came about in a series of meetings, where even helicopters sprinkling water on the city were suggested."
If the trial is successful, the machines will be used across the city when pollution levels rise, according to Hussain.
'Systemic changes' advocated
But many remain skeptical of this solution.
"These only work in a very local situation like a construction site, if you want to douse the dust, then you do this for an immediate and instantaneous effect, but this is not what you would use to control air pollution," Anumita Roychowdhury of the Delhi-based Centre for Science and Environment think tank told CNN.
Pollution control measures should give you sustained improvement over time, she said. "The government needs to focus on systemic changes, infrastructural changes so that they can effectively control pollution across the city."
Known as the Fog Cannon, the machines are made by Cloud Tech, an Indian firm based in Haryana state, which borders Delhi.
On Cloud Tech's website, the company says the Fog Cannon is designed to "tackle the problem of airborne dust particles generated by open mining activities, demolition work and bulk material handling" as well as localized sources of dust, as highlighted by Roychowdhury.
Among the world's worst
Air quality measurements provided by the Delhi Pollution Control Committee track smog levels across the city in real time.
Those levels are based on the concentration of fine particulate matter, PM2.5, per cubic meter. The microscopic particles, which are smaller than 2.5 micrometers in diameter, are considered particularly harmful because they are small enough to lodge deep into the lungs and pass into other organs, causing serious health risks.
The World Health Organization considers a PM2.5 density above 25 micrograms per cubic meter within a 24-hour period as unsafe. In Delhi, an "emergency" level is anything above 300. In November, when a white haze descended on the city, levels topped 1,000 at one point.
The situation is aggravated by Delhi's geography.
The landlocked city sits in a natural bowl and is surrounded by industrial and agricultural hubs.
Without a coastal breeze, like that of Mumbai and Chennai, much of the pollution settles.
In addition, every winter, farmers across fertile neighboring states set fire to their fields to clear them for the next season.
Known as stubble burning, millions of tons of crop residues are set afire.
Though the practice was made illegal in Delhi, Haryana, Uttar Pradesh and Rajasthan following a December 2015 government order, its implementation hasn't been successful.
Roychowdhury, however, is adamant that the strengthening of pollution laws will lead to results.
In October, Delhi rolled out its first Graded Response Action Plan that states what measures must be taken when the concentration of pollutants reaches certain levels. For example, emergency levels mean PM2.5 concentration values above 300 for 48 hours or more. At this level, trucks are banned from entering Delhi, construction work must be halted and schools are shut.
"The city is now legally bound to implement the Graded Response Action Plan, and the other is the Comprehensive Action Plan. This means the government now has an emergency plan as well as one for systemic changes. So, now the entire focus needs to be on getting them implemented with absolute discipline and urgency," Roychowdhury said.
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