Delhi govt to use dust suppressants to combat poor AQI: what are they and do they work?
In 2019, the Delhi Pollution Control Committee had issued directions that all construction agencies will use dust suppressants to control dust emissions and road-owning agencies will use it on dusty patches.
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In 2019, the Delhi Pollution Control Committee had also issued directions that all construction agencies will use dust suppressants to control dust emissions and road-owning agencies will use it on dusty patches. (Representational Image) Dust suppressants will be used in Delhi to mitigate pollution from dust. This, however, is not the first time it has been used in the Capital and parts of NCR.
Dust suppressants may be salts of calcium or magnesium that can absorb moisture. Environment Minister Gopal Rai said the “dust suppressant powder” would be mixed along with water and sprayed on roads to keep the dust down for longer.
In 2019, the Central Pollution Control Board (CPCB) told the NCR states that they may consider using dust suppressants on excavated earth surfaces, piles of construction and demolition waste, and access roads in construction areas.
The CPCB wrote to states that a study was awarded by it on the use of dust suppressants, and its effectiveness was studied for the control of dust generation at certain roads and sites.
“Findings of the study indicate that use of dust suppressant along with water is relatively more effective in control of pollution than conventional methods of dust control i.e. water spraying. About 30% reduction in dust concentration (PM10, PM2.5, and PM1) was observed up to six hours for construction sites as well as roads with the use of dust suppressant,” the CPCB said. The effectiveness of the suppressant was evaluated at three sites in Delhi — construction of the Sarai Kale Khan Road, a building construction site at Narela, and a Dilshad Garden flyover construction site.
An advisory issued by the Delhi PWD in 2019 also noted that the “use of dust suppressants in water can be more effective than plain water sprinkling as it shows more efficiency to reduce particulate matter emission”. The advisory, which mentioned “magnesium chloride hexahydrate flakes,” added that the dust suppressant with bio-additives helps to reduce dust for five to six hours as compared to plain water which lasts for 15 to 30 minutes. Magnesium chloride absorbs moisture.
In 2019, the Delhi Pollution Control Committee had also issued directions that all construction agencies will use dust suppressants to control dust emissions and road-owning agencies will use it on dusty patches.
Anumita Roychowdhury, executive director, research and advocacy, Centre for Science and Environment, said, “We don’t have any information about its efficacy. They claim that if you mix the suppressant, the effect stays for longer, but we are not sure how much longer, and what effect this has in the long term. We haven’t really looked into this.”
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