Repurposing disposable masks and gowns

Both disposable masks and gowns present a physical barrier to infection, standing between the user’s body and the droplet aerosols in the air and other bodily fluids like mucus and blood that pass on coronavirus and other pathogens.

Both Disposable masks and gowns are made with non-woven polypropylene fibres treated with water-repellency.

Disposable Gowns function as a result of their tightly packed needled non-woven construction combined with Durable Water Repellency. The combination of pore size and repellency holds back bodily fluids and microdroplets.

FFP2 and FFP3 (n95 and n99) masks function in the same way as gowns, but in addition have a mid-layer of filter materials to remove microdroplets from the air as we breathe it in. The filter material is made of an extremely fine nanofibre mat which has also been treated with durable water-repellency.

Technical Resources:

Disposable EN-XXXX gown

N-95/FFP2/N-99 FFP3 Mask

Both masks and gowns are treated with a durable water-repellent (DWR) that stops them from becoming soaked though in contact with bodily fluids like mucus, blood or urine. Washing with conventional detergents damages that water-repellency, and increases absorbency once they are dry, potentially allowing a fluid bridge to form across which infection can pass.

Additionally, because Disposable Gowns are non-wovens made with polypropylene, exposing them to temperatures above 40 degrees C causes their tightly packed non-woven fibre construction to relax and increases pore size, making them less resistant to micro-droplets and liquids.

The filter material of FFP2 and FFP3 masks is also extremely sensitive to temperature and relaxes and opens up with hot washing or heat treatment, thereby decreasing air resistance and therefore filter capacity.

Both disposable masks and gowns, because of the polypropylene from which they are manufactured, deform at a macro, micro, and nano level if they are subjected to heat. Since their protective function depends upon fit and pore size within the fabrics, to conserve their original structure they must kept away from heat.

Therefore any cleaning process must be conducted at ambient temperature, and for safety’s sake, below 30°C.

Both disposable masks and gowns need to remain water-repellent and therefore bodily fluid resistant and therefore the cleaning process needs to conserve or even add water-repellency, and remove water-absorbent bodily fluids.

Both masks and gowns need to be cleared of potential pathogens in the cleaning process, and not just Coronavirus. Therefore any sterilization has to be an ambient temperature process already proven within the medical community.

Technical Resources:

Disposable EN-XXXX gown

N-95/FFP2/N-99 FFP3 Mask

To clean gowns and masks, use tools that are available to all hospitals and most homes, notably, a washing machine with a low temperature setting, tumble drier with a low temperature setting or a drying cupboard or cabinet.

Use a proven sterilization chemical that is available both in hospitals and homes. For example, WHO recommends a specific dilution of domestic bleach for cleaning surfaces.

Use a washing product that will remove dirt and bodily fluids whilst conserving water-repellency and wash in cold water to conserve physical properties.

Set up a process within an controlled environment where masks and gowns are marked after each process and discarded after a certain number of cleaning cycles.

Technical Resources:

Disposable EN-XXXX gown

N-95/FFP2/N-99 FFP3 Mask

Risks in cleaning gowns and masks

• The primary risk lies in physical degradation of the equipment by the inadvertent application of heat or over-aggressive washing action.
• Coronavirus infection risk from washed equipment can be considered to be very low because soap and disinfectant are known to easily disable the virus.

Risks with masks

• Masks must be thoroughly dried to avoid moisture obstruction of the filter

Benefits of cleaning and reusing gowns and respirators

• In a crisis situation where supply is low, cleaned gowns and masks should present a much reduced infection risk compared to equipment that is over-used
• Initial testing shows that properly cleaned good quality equipment provides better protection than brand new poor quality equipment, and close to “as good as new” performance
• A less than ideal solution is always better than no solution for a critical problem

Technical Resources:

Disposable EN-XXXX gown

N-95/FFP2/N-99 FFP3 Mask