Titanium dioxide coatings, “self-cleaning” substances used for removal of air pollution, were found to increase the levels of nitrogen oxide, causing ozone pollution.
A study by environmental scientists at Indiana University, published this week in the Journal of the American Chemical Society, claims that instead of removing harmful particles from the atmosphere, titanium dioxide converts ammonia into nitrogen oxide.
The findings suggest that the severity of ozone formation is much greater at areas where the “self-cleaning” chemical was used.
To date, it has been thought that titanium dioxide is a compound that can help the car industry meet the strict air quality standards. When in contact with pollutants, the compound acts as a photocatlyst, breaking down the harmful molecules of ammonia, nitrogen oxides and others as such. These properties of the chemical have been embraced by the industries, using it in paints and surface coatings.
Unluckily, the magic substance that had the potential to prevent pollutants enter the atmosphere, does not prove to be all that harmless. At least not according to Jonathan D. Raff, assistant professor in the School of Public and Environmental Affairs at IU Bloomington and lead author of the study.
Raff claims that the property of titanium dioxide to act as a catalyst in the incomplete breakdown of ammonia to nitrogen oxide, have been overlooked. Reason being that other scientists have mainly focused on much higher concentrations of pollutants, which apparently have caused the confusion.
The problem becomes bigger with the fact that titanium dioxide is used to remove odour-causing organic compounds, and it has even been suggested as a geo-engineering substance that could be introduced to the upper atmosphere.
Hopefully, the team will be able to gain much further understanding in the actual process of breaking down of ammonia using titanium dioxide, and soon they will manage to develop much more effective techniques for pollution control.
