Study finds gaps in evidence for air-cleaning technologies to prevent infections

Summary

A new study led by researchers from the University of Colorado Anschutz Medical Campus and the National Institute for Occupational Safety and Health (NIOSH) through the Centers for Disease Control and Prevention (CDC) finds that although many technologies claim to clean indoor air and prevent the spread of viruses like COVID-19 and the flu, most have not been tested on people and their potential risks are not yet fully understood. Published today in the Annals of Internal Medicine, the research analyzed nearly 700 studies between 1929 and 2024 on engineering controls such as HEPA filters, UV light, ionizers and advanced ventilation systems designed to reduce infection transmission through indoor air. While these technologies are commonly found in homes, schools and public buildings, researchers found just 9% of studies examined whether they reduce illness in humans. “We were surprised to find that most of the research tested air cleaning devices in lab chambers, not in real-world settings where people live, work or go to school,” said Lisa Bero, PhD, professor of internal medicine at the University of Colorado School of Medicine and co-author of the study. “We need stronger studies that look at actual health outcomes, whether people are actually exposed to fewer pathogens or get sick less often, and not just measurements of particles in the air.” Most studies in the review focused on indirect measurements such as tracer gases, dust particles or harmless microbes rather than actual viruses or bacteria that cause illness. Very few tracked whether people experienced fewer infections when using air-cleaning technologies. Studies lack real-world settings “Many of these technologies look promising on paper but we just don’t know if they work in the real world,” said Amiran Baduashvili, MD, associate professor of medicine at the University of Colorado School of Medicine and the paper’s first author. “People are buying and installing these systems in homes and schools hopin...