The national Health Protection Surveillance Centre has reviewed studies on the effectiveness of non medical face masks and visors in preventing the transmission of Covid-19 in public settings and issued a document that you can access here. The document highlights that the most effective non-surgical face coverings have layers of fabric and that visors should extend beyond the ears and below the chin and are most effective when worn with face masks. The HPSC emphasises “Regardless of what face covering is used, it is important to continue public health measures of respiratory etiquette, social distancing and effective hand hygiene, particularly when handling a mask/visor after use.”
The HPSC quotes the World Health Organisation ‘Advice on the use of masks in the context of COVID-19’ (World Health Organization, 2020c) which recommends that visors should only be considered in the following contexts:
“In the context of non-medical mask shortage, face shields may be considered as an alternative noting that they are inferior to mask with respect to prevention of droplet transmission. If face shields are to be used, ensure proper design to cover the sides of the face and below the chin. In addition, they may be easier to wear for individuals with limited compliance with medical masks (such as those with mental health disorders, developmental disabilities, deaf and hard of hearing community and children).” (pg 11)
The Recommendations in the HPSC document are:
o In public settings, when considering the options of cloths face coverings compared with visors, expert opinion and international guidance generally favours cloth face coverings.
o There is a rationale and laboratory evidence in particular for favouring cloth face coverings over visors where the wearer is at a higher level (standing) than those potentially exposed at a lower level (sitting).
o However, there is evidence that visors do reduce exposure to droplets to a certain extent and may be an alternative in certain circumstance including
o People with breathing difficulties
o People who are unable to remove masks/face coverings without help
o Anyone with particular needs who may feel upset or very uncomfortable wearing the mask/face covering
o In settings where people who have learning difficulties or hard of hearing or deaf are present.
o Where cloth face coverings are used, it should be of multiple layers of suitable fabric and correctly applied. Further information on the handling and care of cloth face coverings can be found here.
o Where visors are used they should cover the entire face (above the eyes to below the chin and wrap around from ear to ear) and be correctly applied. Further information on the handling and care of visors can be found here.