Pollution fight: painting roads, lasers among options

A high-level committee in its report to the Supreme Court suggests a slew of pilot projects in Delhi-NCR

Updated - December 17, 2019 01:40 am IST

Published - December 17, 2019 01:39 am IST - New Delhi

Painting roads with photocatalytic coating to clean air, using anti-smog guns at construction sites to reduce dust pollution and setting up of a 20 metre-high ‘smog tower’ with air purifiers are among the pilot projects suggested by a High Level Committee (HLC) to the Supreme Court to control air pollution in Delhi and NCR, said officials.

“In the report submitted to the Supreme Court on Thursday, the HLC also recommended using of wireless sensors and laser methods for monitoring pollution,” a senior official told The Hindu .

On November 25, the Supreme Court had directed to form the HLC and look into the feasibility of these technologies to control and monitor pollution. The HLC has members from Central Pollution Control Board (CPCB), Delhi Pollution Control Committee (DPCC), NEERI, professors from IIT-Delhi, IIT-Kanpur and heads of environmental departments of Delhi, Haryana, Punjab and Uttar Pradesh.

Painting roads

There are companies that develop photocatalytic paints, which can remove pollutants from the air in the presence of sunlight and ultraviolet (UV) rays. “It can be applied on a range of surfaces, such as roofing tiles or even on the surface of roads. Photocatalytic paints contain titanium dioxide [TiO2] which acts as a catalyst when exposed to UV rays and removes atmospheric pollutants,” the official said.

The catalyst converts the pollutants into other species. The committee has suggested that a pilot study may be taken up by institutions such as IISC and IIT-Kanpur in association with Ministry of Heavy Industries to find out the effectiveness of paints using nano materials for cleaning ambient air, including releasing of other undesirable compounds, according to officials.

“But there is a risk that nano materials may result in production of other undesirable species such as nitrous acid and formaldehyde, which will have adverse health impacts,” the official said. Such products have been used by Dubai municipality in parks and also in Mexico.

Smog tower

The HLC has also suggested that a pilot project of “smog tower”, as suggested by an expert panel of IIT-Delhi, IIT-Bombay and Department of Science and Technology, may be taken up.

A panel from IIT-Bombay and IIT-Delhi in association with the University of Minnesota had proposed a 20 metre-high smog tower. The proposal had stated that 65% reduction in pollution can be achieved on an average up to 700 metres from the the tower. It is expected to influence air quality of more than 1 km in the downwind direction, according to officials.

“The committee said in its report that smog towers, as per the current knowledge and experience, may not provide a viable solution to improve air quality on a large scale. But since there is a localised effect, we still want to try it. We are planning to try it in Connaught Place, but are yet to finalise it,” the official added.

Anti-smog gun

Anti-smog gun is a device that sprays nebulised water droplets into the air through high pressure propellers, which help particles to settle down.

“The committee, based on the finding of a study by the CPCB and DPCC, informed the court that anti-smog guns may be effective in controlling localised dust during the period of application and more suitable to high dust emission zones such as large construction sites,” the official said.

After a Supreme Court order on November 25, the CPCB and DPCC conducted tests in Delhi and Gurugram and found reduction in PM2.5 and PM10 levels in areas where the anti-smog guns were used.

Oxy furnace

Oxy furnace uses only oxygen as fuel instead of atmospheric air (which contains nitrogen), thus reducing the production of NOx by about 90% in industries.

“The report recommended that a study led by Ministry of Heavy Industries and Public Enterprises in association with Centre for Development of Glass Industry, National Institute of Foundry & Forge Technology (NIFFT) and others may be conducted to assess feasibility of implementation of oxy furnaces in glass, metallurgical and power industries in India,” the official said.

But the report also said that NOx is mostly released in urban centres from vehicles and not industries.

The committee has also recommended the use of chemical methods, including dust suppressants, to control air pollution.

Wireless Sensor Network

Wireless Sensor Network (WSN) technology to monitor air pollution is still in developmental stage and IIT and NEERI are reviewing its performance.

“The committee has informed that WSN may be used as an indicative monitoring tool for a few activities like mining, large construction sites, to supplement air quality data and report to regulator for conducting further investigation,” the official said.


LiDAR or Light Detection and Ranging is a high-end application of LASER-based technology for monitoring pollution. The HLC has recommended that this technology may be adopted for vertical monitoring at a few places to track transport of pollutants at higher altitude.

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