Air Pollution Solutions: Can Roof Tiles Reduce Pollution?

Air pollution is now the 4^th highest cause of death around the world, contributing to over 7 million deaths globally each year. Many of us are making small changes to help to reduce the amount of pollution in the air, but some people are going the extra mile.

In our six-part series, we’re looking at some of the more innovative solutions to air pollution, including the Smog Free Project and CityTrees. This post focuses on a project by students at the University of California aiming to create pollution-fighting roof tiles.

Cleaning the air

A group of engineering students in California designed, created and produced a coating for roof tiles that can absorb and break down nitrogen oxides, which are particulates often associated with smog. The students estimate that when applied to an average-sized residential roof, the coating could break down enough nitrogen oxides in a year to equal those emitted by a car driving 11,000 miles.

Nitrogen oxides are produced when some fuels are burned at high temperatures. The particles then react with organic compounds in the air and, when in the presence of sunlight, can create smog.

Effective & affordable

In Southern California, where the students conducted their research, around 500 tonnes of nitrogen oxides are emitted every day, contributing to premature deaths, animal fatalities and environmental damage. Every day, around 21 tonnes of the particulates could be eliminated, if 1,000,000 roofs were coated.

The pollution-combatting coating is made out of titanium dioxide (TiO2), a compound often found in cosmetic sunscreens due to it’s light-scattering properties. The students calculated that, to cover an average-sized roof with the TiO2 coating, it would cost around $5 per roof, which converts to just under £3.

How it works

The university students conducted an experiment to see whether their theory, that the coating would break down nitrogen oxides, would stand true. They coated two identical clay roof tiles with different amounts of TiO2 and placed them inside a miniature atmospheric chamber.

The chamber was connected to a source of nitrogen oxides, as well as a device that monitors the levels of the particulates. Using ultraviolet light to simulate sunlight, the students could activate the TiO2 and allow it to break down the nitrogen oxides.

They found that the TiO2 coated tiles removed between 88-97% of the nitrogen oxides, no matter how much coating was used.

Environmental priority

Combatting air pollution can help reduce the amount of water, thermal and soil pollution, leading to a cleaner and brighter environment all-round. But roof tiles aren’t the only option. In our next post, we’ll explore the benefits of city centre vehicle bans. Want to know more about potential solutions to pollution? Take a look at the article ‘Venturi Orifice Steam Traps Reduce Energy Costs and CO2 Emissions’.