A curated starting point for the organizations, guidance, and clean-air tools most useful when preparing for or responding to an air-quality emergency (AQE). The Corsi-Rosenthal box is open-source: it can be built for very little, or bought ready-made. Both paths are below.
The nonprofit founded by Dr. Richard Corsi and Jim Rosenthal to promote clean indoor air and put affordable air purifiers in the hands of those who need them. The home of the open-source Corsi-Rosenthal box, with build instructions, a grant-application path, and a resource hub.
Visit the Foundation →The Corsi-Rosenthal box is open-source and inexpensive to build — a 20" box fan and four MERV-13 furnace filters assembled into a cube. Rather than reinvent the instructions, we point to guides others have developed and, in several cases, laboratory-tested:
The canonical instructions from the design's originators, including the classic five-panel cube.
Open instructions →The federal research program studying how well DIY box-fan filters reduce indoor wildfire smoke, with build considerations and safety notes.
Read the EPA research →A well-established community resource with step-by-step box-fan and Corsi-Rosenthal build guidance and filter-selection tips.
Open the guide →Whichever guide you follow, aim for MERV-13 filters and check the fan-safety guidance for your model.
Ready-to-use, pre-assembled Corsi-Rosenthal–style units built with quiet PC pressure fans and 3M Filtrete filters — the same PC-fan approach AQEPREP recommends. A range of sizes for rooms from bedrooms to larger spaces.
Visit CleanAirKits →Other options worth knowing about: AirFanta makes a low-cost PC-fan CR-style unit, and general marketplaces (e.g., Amazon) list assorted "Corsi-Rosenthal box kits" of variable quality. Verify specifications and filter MERV rating (aim for MERV-13) before buying.
The AQEPREP evidence base and planning tools — including the interactive timelines and the full, verified reference library — for agencies, emergency managers, and clinicians.
Go to the hub →Every scientific claim on this site is backed by a citation checked against the publisher record.
View references →AQEPREP.ORG · Scientific resources are cited and verified against publisher records.