Activated carbon filter air purifier8/11/2023 The products are not regulated, and there are few data on their VOC removal rates, the researchers note. “So there’s this concern in the atmospheric chemistry community that maybe some of these cleaners that claim to be oxidizing away the VOCs are actually generating these harmful byproducts.” “Oxidation of VOCs is what leads to a lot of important pollutants in our atmosphere, such as ground-level ozone or secondary fine particulate matter,” Kroll explains. Most consumer-grade air cleaners contain filters or sorbent materials that can physically trap VOCs, but some products also offer chemical methods of destroying VOCs, such photocatalytic oxidation or ionization using ultraviolet light, plasma technology, or carbon-titanium-dioxide filters. They are a significant source of indoor air pollution, and repeated exposure to some VOCs can cause long-term health problems such as cancer or lung, liver, or kidney damage. VOCs are emitted by thousands of household products, including paints, solvents, glues, cleaning supplies, pesticides, and a variety of cooking and cleaning activities. It is carefully executed, and the results are clearly and thoughtfully presented." “The paper by Jesse Kroll and co-workers is an excellent demonstration of this fact. "During the pandemic, air cleaners have appeared like mushrooms after days of rain, and sadly, some of these air cleaners can introduce chemicals to indoor air that are of greater concern than the chemicals that they might remove,” says Charles Weschler, an expert on indoor pollution at Rutgers University and Technical University of Denmark, who was not an author of the MIT study. The MIT researchers did not test how well the cleaners in their study removed particles of any kind from indoor air. The popularity of indoor air cleaners has soared in the past year, as most cleaners advertise the ability to remove particles, including those that contain exhaled viruses such as SARS-CoV-2. “This work shows that, for at least some consumer-grade portable air cleaners that claim to remove VOCs from indoor air, VOC removal may actually be minimal, and the air delivered may contain additional VOCs and/or oxidation byproducts, some of which are known to be harmful to human health,” the researchers write in the journal Environmental Science and Technology Letters. In some cases, the chemical reactions led to byproducts, such as formaldehyde, that added to the overall pollutant level. The chemical reactions that were supposed to remove VOCs played a minor role in the cleaners’ operations, with physical removal of the pollutants through the cleaner’s absorbents or filters doing most of the work. What’s more, the effectiveness of VOC removal varied considerably among the four products examined in the study, professor of civil and environmental engineering and chemical engineering Jesse Kroll and colleagues found. Consumer-grade air cleaners that promise to reduce indoor levels of volatile organic compound (VOC) pollutants using chemical oxidation can be a source of VOCs themselves, according to a new study led by MIT researchers.
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