Clean Air 

The viruses that cause COVID-19 and the flu spread much easier in crowded rooms with poor air flow. Ventilation and filtration also help by removing allergens, asthma triggers, and dust from the air. To reduce spread of viruses, combine use of these filters with other protections like masks, distancing and vaccination.


What is a Corsi-Rosenthal (CR) box?

A CR Box uses everyday items found in hardware stores, is easy to make, affordable, and helps your space have safer indoor air. Experts on indoor air quality invented this box so many people could have access to clean air in the rooms they use day-to-day.This box can have an immediate impact on your health! And because it is a fraction of the cost of commercial HEPA filters, units can be installed and clean the air for more people.


For more information on how to build a box yourself, check out this guide from UC Davis or check out these resources from the Clean Air Crew


Filters must be replaced every 6-9 months. 

  • The fan can be used to create a new CR Box, but the filters need to be replaced every 6-9 months or when obviously dirty.
  • When it's time to replace the filters,
    • be sure not to release any dust.
    • Let them sit with the fan off for 2 days.
    • Carefully cut the duct tape and place the filters in a large trash bag without crushing or bending the filters.
    • Seal the trash bag. Wipe down the fan with a wet paper towel or baby wipe before reusing.


CR Box Build Instructions 

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