HEPA purifiers do not fully reduce classroom viral exposure

A secondary analysis from Mass General Brigham has revealed that respiratory viral exposure remains high in classrooms, even with high-efficiency particulate air (HEPA) purifiers in use. The study, conducted in 200 classrooms, indicates that further measures are necessary to mitigate viral presence in school environments.

The findings, published in JAMA Network Open, showed that air samples from the classrooms contained an average of three different respiratory viruses, with some samples containing up to 13 viruses, including respiratory syncytial virus (RSV) and influenza. Researchers noted that air purifiers did not significantly reduce the overall viral load in these spaces.

The original trial sought to determine whether HEPA purifiers could alleviate asthma symptoms among elementary school students. Although classrooms with HEPA purifiers exhibited a modest 32.8% decrease in viral diversity, this outcome did not correlate with a reduction in school absences. Furthermore, lower humidity levels were associated with increased viral exposure, suggesting that humidity control may be vital in reducing infection risks.

As schools continue to manage respiratory health, the research emphasizes the importance of considering factors beyond air filtration, such as maintaining classroom humidity between 40% and 60%.