UK Government guidance issued May 2020 strongly discourages local NHS trusts from accepting non-CE marked products. More generally, when deciding what face shields are acceptable you need to consider:

• Your use case and the risks involved
• Local procurement requirements, including whether CE marking is required and how much visibility or documentation you need about production processes and quality control procedures. 
• Whether you will reuse the shields (and if so, what materials/manufacturing processes are acceptable for your sterilisation procedures).
• Whether you will sterilise shields on delivery, or need a robust sterile manufacturing and distribution process, or require a quarantine period.

If you would like some assistance working through these considerations, please feel free to get in touch.

UK Regulations

Briefly, the key UK regulatory requirements (EN166 requirement and associated test standards in EN 167 and EN168) on the design of face shields are:

• Face shields must provide eye protection from direct (line of sight) droplets from the front and 90° to the left and right, and from horizontal and 45° above and below.
• Headbands must be at least 10mm wide and adjustable or self-adjusting.
• Visors must be free from marks and defects affecting clarity, with optical transmission above 74.4% and satisfactory refractive and diffusive optical properties.
• EU 2016/425 also requires that face shields must Include a manufacturer’s identification mark. 

Some of these tests can be performed yourself (for example ensuring headband is 10 mm minimum width, eye coverage which should be part of the design criteria) , others can be verified using the materials data sheet (for example optical transmission of the material) and others can only be performed by specialist test houses (for example refraction and diffusion tests although if the shield is perfectly clear and does not blur fine print it is likely to pass). Testing houses are often willing to conduct a quick test of shield materials in advance of a formal test.

There are also regulations that cover the manufacturing and distribution of face shields (the Essential Safety & Performance Requirements detailed in REGULATION (EU) 2016/425) which suggest at a minimum a technical file containing:

• Requirements Specification
• Risk File (covering all risks, both arising from use and manufacture)
• Design Validation
• Material Data sheets and supplier information
• Manufacturing SOP (including Manufacturing SOP Checklist, Label Content)
• Instructions for use

Please note that this is not an exhaustive list, and that we are not regulatory officials. Our description is intended to provide an indication of what is needed to obtain regulatory approval.

See also how to safely supply homemade or 3D printed PPE face shields.

Sterilisation/Disinfection

Face shields aren’t traditionally considered an item that is required to be sterile (defined as not containing microorganisms), as they are unlikely, for example, to be in contact with an open wound. However, it is crucial that anything that will be worn or handled is disinfected to ensure it is not harbouring any viable virus. 

Quarantine: One way this can be achieved is by ‘quarantining’ materials, as the virus can only survive for a limited time outside of a host body. The timing depends on the material, for plastics it has been measured to be non-viable after three days, so a five day quarantine has been deemed acceptable by some UK hospitals, including Addenbrooke's Hospital's Clinical Engineering Department. This quarantine period can be before or after manufacturing, provided the manufacturing, packing and shipping can be sufficiently controlled to be kept contamination free. 

Hospital sterilisation techniques: A more timely approach is to use traditional hospital sterilisation techniques, where available and accepted.

Production techniques

Community led face shield production uses a variety of technologies, many in combination, each with their own trade offs:

3D printed

• Possible to use chemical disinfection but 3D printed materials are likely to erode over time -- recommend visual inspection before each use
• Many design options
• Quality can be variable especially if produced by many distributed manufacturers with different printers, different settings and different levels of expertise

Laser cut

• Can be shipped flat packed
• Easy to  disinfect by wiping down
• Fully laser cut designs can be flimsy and important to ensure that cut edges are bevelled and  do not have sharp edges

Die cut and vacuum formed

• Rapid production (<1sec each)
• Easy to disinfect by wiping down
• Die cut process can leave little burrs or tags that may need to be removed

Injection molded

• Rapid production (<1min each)
• Need to check design and mould for any manufacturing weaknesses or burrs
• Tends to self sterilise , but environmental and handling controls still required

Hand fabricated

• Slow
• Variation between individual items likely

A note about clear visor production

• Whichever process you are using, there is a need to check that the manufacture process prior to cutting (e.g. roll cutting into sheets) and shield cutting itself does not result in scouring or marks on the shields that damage visibility as this will cause a product to fail its EN 166 testing.
• Ideal to protect shields is the use or protective film on each side of the shield that is removed by the user prior to use. This reduces the risk of damage but does not guarantee lack of damage so manufacturing processes should always be subject to first article inspection and batch quality control procedures.