Breathe Easy: Corsi-Rosenthal Boxes Reduce Indoor Air Pollution

Researchers from Brown’s School of Public Health and School of Engineering along with the Silent Spring Institute find low-cost DIY air filters effectively improve indoor air quality.

During the early days of the COVID-19 pandemic, environmental engineer Richard Corsi began exploring cheap and easy ways to reduce the transmission of the coronavirus. His concept of a DIY air cleaner was taken up by Jim Rosenthal, CEO of filter manufacturer Tex-Air. Rosenthal found that the boxes were surprisingly effective at filtering COVID-19 aerosol particles at a fraction of the cost of commercial HEPA systems.

Brown University’s first group of Corsi-Rosenthal Boxes (CR Boxes) were assembled in the fall of 2021 by student and staff volunteers to help mitigate the spread of COVID-19 on campus. Joseph Braun, associate professor of epidemiology, was quick to ask if these inexpensive air-filtration systems would effectively reduce indoor air pollutants. A year later, the answer is a ringing ‘yes.’

On November 17, Braun presented his preliminary findings at the School of Public Health. He noted that indoor air pollutants are linked to a variety of health problems, including asthma, reduced vaccine response, decreased birth weight, altered brain development in children, altered metabolism, and some cancers. Many indoor pollutants are also endocrine-disrupting chemicals that may mimic or interfere with the body’s hormones.

Importantly, Braun’s research team found that CR Boxes significantly decreased indoor concentrations of PFAS in the 17 rooms they studied in the School of Public Health. PFAS, man-made chemicals commonly found in cleaners, textiles, leather, paper, paints, and wire insulation, decreased by 40 to 60%. CR Boxes also reduced phthalates, which are found in hundreds of products including building materials, personal care products, and some plastics, by 30 to 60% in almost all of the rooms studied.


However, CR Boxes also increased sound levels by an average of five decibels during the day and ten decibels at night, causing occupants at the School to sometimes turn them off. For Braun and the study’s co-authors – Kate Manz, assistant professor of engineering; Kurt Pennell, 250th Anniversary Professor of Engineering; Jamie Liu, postdoctoral research associate in epidemiology; Shaunessey Burks, MPH candidate; Richa Gairola, senior data analyst at Brown; Robin Dodson, associate director of research operations at Silent Spring Institute; and Elissia Franklin, postdoctoral research fellow at the Silent Spring Institute and Northeastern University – the conclusion is clear: the CR Box is a significant non pharmaceutical intervention that mitigates the spread of COVID-19 and reduces exposure to indoor air pollutants. Their next step is to determine if the boxes also reduce pollutant levels in the body.