Smog Stories: Can Your Walls 'Eat' Pollution? Expert Explains Science Behind 'Smog-Eating Surfaces'

Smog Stories: As air pollution continues to choke Delhi, deliberations and debates continue on possible solutions to deal with the hazard. 'Smog-eating surfaces' have emerged as a unique and innovative solution beyond traditional pollution-control measures. The technology behind these surfaces is designed to actively reduce air pollution by breaking down harmful pollutants. Studies suggest that these surfaces can reduce nitrogen dioxide levels locally, especially in high-traffic areas.

The Daily Jagran spoke to Kaleshwar Mishra, co-founder, Green India Foundation, to understand what smog-eating surfaces are and how do they work.

What Are Smog-Eating Surfaces?

Explaining the science behind 'smog-eating surfaces', Mishra said, "These surfaces utilise a process called photocatalysis, fueled by a titanium dioxide coating that acts like reverse photosynthesis. When sunlight hits the surface, it triggers a reaction that captures nitrogen oxides and chemically converts them into harmless nitrate salts."

"Essentially, the building or road stops acting as a passive structure and begins functioning as a chemical sponge that scrubs the air and washes itself clean during rainfall."

In simple terms, the surface uses sunlight to "digest" pollution, hence the term smog-eating.

Where can this technology be used?

These surfaces can be applied to buildings, roads, pavements, tiles, and even paint, turning everyday urban structures into passive air-cleaning tools.

Highlighting the economic value of this technology, Mishra said, "Beyond the environmental altruism of creating a 'clean air island' for residents, the immediate economic benefit is the self-cleaning property of these materials. The same reaction that breaks down smog also decomposes organic dirt and prevents mold growth, meaning facades stay pristine longer with lower maintenance costs."

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Which countries and cities have used technology and where India stands?

Several countries around the world have experimented with smog-eating surfaces:

• Italy has installed photocatalytic concrete on roads and pavements.
• The Netherlands has tested smog-eating tiles in urban areas.
• Mexico City installed a smog-eating facade on a hospital building.

Currently, India has seen pilot projects using smog-eating paint on flyovers and public buildings but the large scale implementation is still far from reality.

Benefits of Smog-Eating Surfaces

• Passive pollution control: No electricity or machinery required.
• Urban scalability: Can be applied to existing infrastructure.
• Low maintenance: Sunlight and rain keep the process going.
• Aesthetic integration: Works as paint, tiles, or concrete without altering city landscapes.

Limitations and Concerns

Smog-eating surface technology is silver lining but not a silver bullet. Their effectiveness is limited to the immediate surroundings and depends heavily on sunlight, weather conditions and pollution levels.

Additionally, they cannot replace strong emission controls, cleaner fuels, or better public transport.

Their long-term durability, costs, and the environmental impact of byproducts, are a matter of concern although current research suggests these risks are minimal.

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Challenges in implementing technology

"We need massive surface area coverage to significantly impact city-wide air quality. Furthermore, the technology relies entirely on UV light and direct contact; if the surface is shaded or covered in ordinary grime like oil or gum, the photocatalytic reaction stops. It requires consistent exposure to light and maintenance to remain effective," Kaleshwar Mishra stated.

What residents can do with it?

Speaking about the initiatives that can be taken at resident-level, Kaleshwar Mishra said, "Residents don't have to wait for municipal infrastructure updates to make a difference; they can deploy this technology at the household level immediately. By choosing photocatalytic exterior paints for renovations, or using treated paving stones for driveways, individual homeowners can transform their properties into passive air purification stations."

(This article is part of the series 'Smog Stories'. To read more articles in the series, click here)