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Daily disposal of clinical masks and gowns in a coronavirus context has created acute shortage worldwide.


Repurposing disposable masks and gowns


The 2020 Coronavirus crisis has massively increased the demand for PPE, worldwide. In most countries, masks and gowns are largely disposable items. Clearly, if medical practitioners were able to use their gowns more than once, the supply problems would be divided by the number of uses.

Could disposable masks and gowns be re-used more safely?

Reference Library

Click here for a list of relevant PDFs and links we have collected together whilst doing our research.

5 Key Questions:

Breaking it down, we need answers to the following:

1. What do disposable masks and gowns actually deliver and how?

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.

2. How could performance be compromised by cleaning and why?

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.

3. How can we avoid damaging performance whilst extending life and ensuring safety?

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.

4. How can we achieve life extension of disposable masks and gowns practically with the tools easily to hand?

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.

5. What are the risks and benefits of applying a cleaning process to make the re-use of disposable masks or gowns safer?

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
QUESTION SHORT ANSWERS Standards and Processes: Masks
 
Standards: Gowns Nikwax Papers
1. What do disposable masks and gowns actually deliver and how? Bodily Fluid Resistance, Water-repellency, Particulate Filtration, Microdroplet Filtration, Physical barrier to infection
 
EN 149:2001 + A1:2009 Respiratory protective devices

EN 14683:2019 Medical face mask
 
EN 13795 -Drapes and Gowns Nikwax Single Use Gown Testing
2. How could performance be compromised by cleaning and why? Increased Air Permeability, Higher liquid (water) absorbency, Reduced particulate filtration, Compromised fit, Residual cleaning chemical
 
BS EN 14476:2013+A2:2019 BS EN 14476:2013+A2:2019 Nikwax Single Use Mask Testing
3. How can we avoid damaging performance whilst extending life? Wash Cold, Dry Cool, Avoid persistant wetting agents, Avoid abrasion
 
EN 149:2001 + A1:2009 Respiratory protective devices

EN 14683:2019 Medical face mask
 
EN 13795 -Drapes and Gowns As above
4. How can we achieve life extension of disposable masks and gowns practically with the tools easily to hand? Established re-waterproofing technology, Dedicated cold wash-cycle, Known cold temperature broad spectrum disinfectant that does not compromise repellency
 
ISO 18184:2019 Textiles- Determination of antiviral activity of textile products ISO 18184:2019 Textiles- Determination of antiviral activity of textile products As above
5. What are the risks and benefits of applying a cleaning process to make the re-use of disposable masks or gowns safer? Risks: Poor Quality Control, Inadvertent application of standard cleaning protocols Benefits: Improved protection during PPE supply shortage
 
Not applicable Not applicable As above
6. How could this knowledge be applied practically by people in the field? Recommended wash cycles, recommended drying routines, recommended cleaning agents
 
In progress In progress As above