Brigham and Women's Hospital Oct 10 2025 In a secondary analysis of a study of 200 classrooms, Mass General Brigham researchers found respiratory viral exposures were still high in those with HEPA purifiers, suggesting additional interventions are needed. School is in session, and viral illness is on the rise. A new study suggests that lowering exposure to respiratory viruses in classrooms isn't as simple as adding high-efficiency particulate air (HEPA) purifiers to the room. In a secondary