How Smog-Eating Paint Could Help Turn City Surfaces Into Pollution Fighters. Should Delhi-NCR Try This?

This story is part of “How Does It Work?” — The Better India’s series that takes the everyday things you see, use and rely on, and uncovers the clever technology, design and sustainable thinking that makes them work better. From the objects in your home to the systems around you, we break down the ideas behind them in simple, easy-to-understand language. Because innovation isn’t always about futuristic machines or complicated technology. Sometimes, it’s hiding in the things we use every day.

In just a couple of months, the air across Delhi-NCR will start feeling different.

The skies will turn hazier, morning walks may become less inviting, and checking the air quality index could become as routine as checking the weather. For many people, winter also means reaching for masks, keeping windows shut, and wondering whether that familiar layer of haze is fog, smog or a bit of both.

And this is not only a Delhi problem. Air pollution affects people across Indian cities, with pollutants such as fine particulate matter, nitrogen dioxide and other harmful gases contributing to respiratory and cardiovascular health risks.

But what if, alongside efforts to reduce these pollutants at their source, some of the surfaces around us could help break down a few of them too?

That is where smog-eating paint comes in.

What exactly is smog-eating paint?

Despite the catchy name, this is not ordinary paint that traps a layer of smog.

These are photocatalytic coatings — special surface coatings that typically contain a material called titanium dioxide (TiO₂). The material has been studied for photocatalytic applications since at least the 1980s, including self-cleaning surfaces and pollution control.

The idea is simple: use sunlight to trigger a chemical reaction on a painted or coated surface, allowing it to break down certain harmful pollutants that come into contact with it.

The concept has already been explored outside India. In the Netherlands, for instance, researchers have tested TiO₂-based coatings and concrete surfaces for reducing nitrogen oxides around roads.

Now, the idea is being studied in Indian conditions too.

In March 2026, the Delhi government signed an MoU with IIT Madras for a study of photocatalytic “smog-eating” surfaces. Researchers are examining whether TiO₂-based coatings on roads, pavements and other surfaces can help reduce pollutants such as nitrogen dioxide (NO₂) and volatile organic compounds (VOCs).

So, how does it actually work?

Think of titanium dioxide as a tiny chemical helper that wakes up when light falls on it.

When sunlight hits the TiO₂ in the coating, it provides the energy needed to trigger a photocatalytic reaction. This creates highly reactive particles on the surface. They interact with pollutants in the air, helping oxidise and transform them into less harmful substances.

For nitrogen oxides, for example, the reaction can ultimately convert them into nitrate compounds on the surface. VOCs can also be broken down through similar oxidation reactions.

In simple terms, the coating uses sunlight to turn a normally passive surface into a tiny chemical reaction zone.

That means a road, pavement, wall, or building surface could potentially do more than simply sit there. If enough suitable surface area is exposed to light and air, it could contribute to reducing certain pollutants around it.

Can it really clean Delhi’s air?

This is where the science gets interesting; photocatalytic coatings have shown promising results in laboratory experiments and some real-world demonstrations, but their performance outdoors can vary considerably. 

Sunlight intensity, humidity, temperature, wind, dust, and how long polluted air remains in contact with the surface can all affect the reaction. Reviews of outdoor studies have found widely varying results, which is why researchers recommend testing the technology under specific local conditions.

That is also why the IIT Madras-Delhi government study matters. Researchers plan to test the coatings under different lighting conditions and in Delhi-like pollution environments before assessing how they could be deployed.

And there is an important catch: smog-eating coatings are not meant to replace pollution control at the source.

Reducing vehicle, industrial, construction, and other emissions remains essential. The coating is being explored as an additional tool — one that could make the huge surfaces already surrounding us work a little harder for cleaner air.

So, the next time a wall or road looks like just another grey stretch of the city, imagine it doing something else too: using a little sunlight to help break down some of the pollutants floating around us.

Sources:

‘Can Paint Help Tackle Delhi’s Deadly Smog? Discover the Future of Air Purification’ by Sleepy Classes IAS.

Disclaimer : This story is auto aggregated by a computer programme and has not been created or edited by DOWNTHENEWS. Publisher: thebetterindia.com