The following is a do-it-yourself (DIY) design for a low-budget PAPR mask using readily accessible materials and a 3D printer. This design has not been approved by any federal regulating body and as a result, is a design guideline only. Use this at your own risk.
Powered Air Purifying Respirators (PAPR) are motorized (battery powered) systems that deliver continuous flow of filtered air. As a type of personal protective equipment (PPE), PAPR masks are used in situations where particulates, gases and vapor hazards exist. The COVID-19 pandemic has created a strain on our hospitals and health workers, leaving a shortage of supplies and PPE that our health care workers need to successfully perform on the frontlines. This guide was created to offer assistance in providing PPE to those in dire need. The goal was to create an easy, low-cost solution using readily accessible materials and a 3D printer. This design does not replace commercial PAPR masks but to offer a short-term solution until our supply-chain infrastructure can keep up with demand. Current commercially available PAPR Masks range from a couple hundred dollars to a couple thousand dollars. In stark contrast, this design costs about $40. PAPR Masks can vary between facepiece mounted designs (the blower is mounted on the facepiece or helmet) or belt-mounted (the blower is mounted on the belt) as well as between tight-fitting half masks, tight-fitting full facepieces, hoods, loose-fitting facepieces or helmets. AS Per CDC guidelines, tight-fitting facepieces require a minimum of 4 cfm (115 lpm) and for loose-fitting facepieces a minimum of 6 cfm (170 lpm) https://wwwn.cdc.gov/NIOSH-CEL/Limitations/Papr
. In addition, loose-fitting facepieces do not require fit testing, while tight-fitting facepieces do require fit testing with the blower turned off https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3fittest.html
In order to create an easy, low-cost solution using readily accessible materials, the parts used within this guide can be found either at your local pharmacy store (clear disposable shower caps, elastic wrap), Home Depot (tubing, HEPA Filters) or Amazon (with fast delivery within a couple days). Sourcing materials became one of the more difficult tasks, negotiating between what part is available quickly vs the optimal part. The critical components of this DIY PAPR are the blower and the HEPA filter. In order to meet the minimum requirements from CDC, a blower fun for a loose-fitting mask requires a minimum of 6 cfm. 5V is a good voltage to pickup as there are readily available battery packs that operate at this voltage used to charge phones. As a result, the blower fan here at 5V/0.3A and 11.94CFM is sufficient to meet the minimum requirements while operating for at least 12 hours without a single charge on a 5V 10000mAh battery. Additionally, small HEPA filters designed for a Roomba or portable airpurifier would suffice to filter the air into our DIY PAPR. This resulted in a total cost of ~$40. Disposable shower caps provided an easy way to help sanitization, as these were to be disposed after every use, as well as mitigating any custom face-masks that would have needed to be assembled.
A number of varying prototypes were tested and iterated throughout the design process. From starting with 5V and 12V axial fans to test its CFM and power; to varying headpieces and adaptors to provide not only sufficient airflow to our facepiece, but to also provide maximum flexibility and comfortability. As a result, shown here are two suggested designs, one which the blower is mounted on the waist (or mid-chest) and one which the blower is mounted on the neck. While the placement of the blower mounted on the neck provides a tight-and compact solution, it doesn’t provide the best comfortability and flexibility as opposed to the blower mounted on the waist. Both designs are shown to provide the possibility of each with minimal alterations in the size of the belt or elastic wrap as well as the tubing from the ventilator box to the facepiece.