Dutch researchers have found that pavers containing titanium dioxide – a common ingredient in sunscreen – can significantly reduce harmful airborne pollutants from vehicle emissions in urban areas. -Photo: Science Direct

Surfacing advances are improving water quality and reducing urban heat island effects as more builders discover the benefits of permeable and porous pavements. New research could add air purification to the growing list of paver possibilities.

Findings published by the Eindhoven University of Technology in the Netherlands found that surfaces treated with a photocatalytic – that is, an element that accelerates a chemical reaction when exposed to light – can substantially reduce airborne pollution on a normal city street.

The university's experiment was conducted over a one-year period, on two adjacent streets in Hengelo, eastern Netherlands. Researchers measured the air quality of a 100-meter stretch of standard pavement on one street against a 150-meter "test street' of concrete pavement containing titanium oxide, a photocatalytic that removes pollutants like nitrogen oxide (NOx) from the air and converts them into inert nitrates.

Both streets were measured for levels of NOx, and the test street managed to reduce air pollution by up to nearly half (45 percent) in ideal weather conditions, and by nearly a fifth (19 percent) over a whole day.

"This latest research shows the potential of chemically engineered surfaces to further improve our quality of life, especially in major urban areas where traffic emissions are high," said David Brown, chief executive at the Institution of Chemical Engineers.

Auto emissions are a major cause of NOx gases, and the potential for reducing air pollution with photocatalytic surfaces has been known for several years. Permeable surfacing containing titanium oxide – an active ingredient in sunblock, incidentally, that can be easily converted into a spray – was used by architect Richard Meier on the concrete exterior of the Jubilee Church in Rome in 2003, and similar material was installed in Chicago's Mary Bartelme Park in 2010. Both sites have also reported improved air quality, and the results of the Eindhoven University tests could provide a scientific basis for increased use of treated surfacing.

The full text of the study, published June 15 in the Journal of Hazardous Materials, is available at this link.