Concerns are raised that even people who have not suffered direct damage from the large wildfires in the country could experience aftereffects. Wildfires destroy ecosystems and cause human and property damage while also resulting in severe fine dust pollution. The United States, which faces large wildfires every year, has seen its average annual fine dust pollution increase by 30 to 50% in recent years.
Scientists have developed an inexpensive indoor air purifier that can remove pollutants caused by wildfires. Compared to traditional air purifiers that primarily use high-performance HEPA (High-Efficiency Particulate Air) filters, the expense has been reduced by up to one-eighth, while maintaining similar pollutant removal efficiency.
Richard Corsi, dean of the University of California, Davis (UC Davis) College of Engineering, disclosed research results on 'DIY (Do It Yourself) air filters' at the American Chemical Society (ACS) spring meeting on the 24th. Professor Corsi named the air filter 'CR (Corsi-Rosenthal) box' after himself and his co-developer, Jim Rosenthal, a researcher.
The CR box consists of four air filters commonly used in heating, ventilation, and air conditioning systems, along with a cardboard box and a fan that draws air in and sends it toward the ceiling. The research team stated that due to the simplicity of the components, the manufacturing expense is only one-third to one-eighth of that of existing commercial HEPA filter air purifiers.
The research team created the CR box due to the recent surge in wildfires impacting indoor air quality. The smoke generated by wildfires spreads with the wind, infiltrating homes, schools, and offices. If such air pollutants are not properly handled, they can cause harm to human health.
The researchers installed CR boxes in four locations on the UC Davis campus to test their durability and performance. They operated the CR boxes for 2,500 hours, roughly equivalent to two semesters. The CR box demonstrated performance comparable to that of HEPA filters. It was found to be more effective in removing fine particles sized between 0.35 and 1 µm (micrometers, where 1 µm is one-millionth of a meter). Generally, smoke particles generated from wildfires are smaller than 1 µm, while dust and pollen range from 0.5 to 3 µm in size.
The CR box removed not only external air pollutants that entered but also particles emitted by people talking indoors. The air filtration system functioned adequately as long as the CR box was within 2.44 meters of people.
The research team plans to improve the CR box to reduce noise significantly compared to existing commercial air purifiers and also to remove other air pollutants such as ozone and smog. Professor Corsi noted, 'The most satisfying aspect of the CR box is that the people involved in creating it gained a sense of fulfillment from making something that helps themselves, their families, and their students.'
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