Clean Air Simplified

A study led by Professor Joseph Braun found that inexpensive, easy-to-assemble Corsi-Rosenthal boxes effectively filter out indoor air pollutants.

A team of researchers from Brown University’s School of Public Health, Brown’s School of Engineering and Silent Spring Institute found that simple air filtration devices called Corsi-Rosenthal boxes are effective at reducing indoor air pollutants.

The study, which analyzed the effectiveness of Corsi-Rosenthal boxes installed at the School of Public Health to help prevent the spread of COVID-19, is the first peer-reviewed study of the efficacy of the boxes on indoor pollutants, according to the authors. The study also collected data regarding indoor air concentrations of commonly-found chemicals.

“The findings show that an inexpensive, easy-to-construct air filter can protect against illness caused not only by viruses, but also by chemical pollutants,” said lead author Joseph Braun, an associate professor of epidemiology. “This type of highly-accessible public health intervention can empower community groups to take steps to improve their air quality and therefore, their health.”

Corsi-Rosenthal boxes can be constructed from materials found at hardware stores: four MERV-13 filters, duct tape, a 20-inch box fan and its cardboard box. As part of a school-wide project, boxes were assembled by students and campus community members and installed in the School of Public Health as well as other buildings on the Brown University campus.

To assess the boxes’ efficacy at removing chemicals from the air, Braun and his team compared a room’s concentrations of semi-volatile organic compounds before and during the box’s operation.

“ This type of highly- accessible public health intervention can empower community groups to take steps to improve their air quality and therefore, their health. ”


The results, published in Environmental Science & Technology, showed that Corsi-Rosenthal boxes significantly decreased the concentrations of several PFAS and phthalates in 17 rooms at the School of Public Health during the period

they were used (February to March 2022). PFAS, a type of synthetic chemical found in a range of products including cleaners, textiles and wire insulation, decreased by 40% to 60%; phthalates, commonly found in building materials and personal care products, were reduced by 30% to 60%.

PFAS and phthalates have been linked to various health problems, including asthma, decreased birth weight, altered brain development in children, altered metabolism and some cancers, said Braun, who studies the effect of these chemicals on human health. They are also considered to be endocrine-disrupting chemicals that may mimic or interfere with the body’s hormones. What’s more, PFAS have been associated with reduced vaccine response in children and also may increase the severity of and susceptibility to COVID-19 in adults.

“The reduction of PFAS and phthalate levels is a wonderful co-benefit to the Corsi-Rosenthal boxes,” said study co-author Robin Dodson, a research scientist at Silent Spring Institute and expert in chemical exposures in the indoor environment. “These boxes are accessible, easy to make and relatively inexpensive, and they’re currently being used in universities and homes across the country.”

The researchers also found that the Corsi-Rosenthal boxes increase sound levels by an average of 5 decibels during the day and 10 decibels at night, which could be considered dis- tracting in certain settings, such as classrooms. However, Braun said, the health benefits of the box likely outweigh the audio side effects.

“The box filters do make some noise,” Braun said. “But you can construct them quickly for about $100 per unit, with materials from the hardware store. They are not only highly effective but also scalable.”

Other Brown study authors include Kate Manz and Kurt Pennell from the School of Engineering, and Jamie LiuShaunessey Burks and Richa Gairola from the School of Public Health. This research was supported by the National Science Foundation and the National Institute of Environmental Health Sciences.

Building a Corsi Cube – DIY


Video courtesy of UC Davis College of Engineering