How Photocatalytic Coating Turns Buildings into Air Purifiers

Created By RISC | 2 weeks ago

Last modified date : 2 weeks ago

PM2.5 never seems to really go away… So what can we do?

Fine particulates with a diameter of 2.5 microns or less—30 times smaller than the width of a human hair—can enter our bodies through our respiratory system and even reach our bloodstream. Exposure to PM2.5 can cause eye, nose, and throat irritation. Breathing can become difficult and we might feel chest pain. Long-term exposure may increase the risk of cardiovascular diseases and respiratory conditions such as chronic obstructive pulmonary disease (COPD).

Outdoor air pollution and PM2.5 are classed in Group 1 (Carcinogenic to Humans) by the International Agency for Research on Cancer (IARC). There is enough evidence to confirm their role as carcinogens. PM2.5 causes lung cancer, according to research.

We can protect ourselves from PM2.5 with N95 masks or air purifiers with HEPA filters (H10–H14), able to trap particles as small as 0.3 microns with an efficiency of 85%–99.995%.

But did you know that some building materials reduce dust?

Photocatalytic coating is a surface treatment that can reduce pollution. This coating often contains titanium dioxide (TiO2). When it’s exposed to sunlight, a chemical reaction on the surface generates hydroxyl radicals (OH·) and superoxide anion radicals (O2-·). These radicals break down air pollutants including dust, gases, bacteria, viruses, and mold. The pollutants form carbon dioxide (CO2) and water (H2O), making them harmless to health. Research has shown that titanium dioxide can decompose up to 92% of the carbon content in PM2.5 while releasing carbon dioxide, effectively reducing the harmful impact of PM2.5.

Photocatalyst coatings are already widely applied to construction materials such as glass, roofing materials, and wall paint. These coatings help surfaces clean themselves by preventing the accumulation of dust and pollutants. They also inhibit the growth of bacteria and mold. And they help cool buildings, ultimately reducing energy consumption.

Story by: Supunnapang Raksawong, Materials Researcher in Sustainable Building Material, RISC

References:
IARC Monographs. Outdoor Air Quality Volume 109
Dr. Piboon Jinawat. "Photocatalyst Building Materials." National Academic Conference, Architectural Paradigm, 2015
Misawa K, Sekine Y, Kusukubo Y, Sohara K. Photocatalytic degradation of atmospheric fine particulate matter (PM2.5) collected on TiO2 supporting quartz fiber filter. Environ Technol. 2020 Apr;41(10):1266-1274.