Ministers know which masks provide the best Covid protection

Nov 23, 2023

Now that we better understand how the virus spreads, increasing the use of FFP2 and FFP3 masks should be a priority

It is now accepted unequivocally that the virus responsible for Covid-19 is airborne, travelling metres on an infected person's breath within liquid microdroplets and aerosols. One of the most important measures to prevent transmission of an airborne respiratory virus is the use of masks. Any face covering is better than nothing, but in the UK the government hasn't informed people about the most effective protection, or ensured that they have access to it.

Nearly two years into the pandemic, official guidance remains confusing. The government still discourages non-healthcare workers from obtaining PPE, including certified respiratory protection, stating that it is used in a limited number of industrial and healthcare settings.

As a result, high-quality masks are not standard issue, even among healthcare workers. Very few beyond critical-care teams have been supplied with effective respiratory protection. This is despite studies showing they could reduce infections among hospital staff. This week, the British Medical Association and other medical organisations called for all frontline NHS staff to be supplied with effective respiratory protection.

The government is not averse to mask regulations in general. In England, it became law to wear a face covering on public transport on 15 June 2020 and a second law, covering public indoor areas, such as retail spaces and places of worship, came into effect five weeks later. Both laws were revoked on 18 July 2021, on the eve of "freedom day". As a response to the threat of Omicron, a new law enforcing face coverings on public transport and in some indoor spaces was brought into force on 30 November. Similar laws are in place in the devolved nations.

However, the regulations say little about the best kind of protection. The laws for the public enforce the use of "face coverings", not "face masks". The government defines a face covering as "something which safely covers the nose and mouth". This may be made of cloth; the government recommends a comfortable, breathable material, such as cotton. The guidance says that, by covering the nose and mouth, such coverings protect the wearer and others against the spread of infection.

This is only partially true. The guidance dates back to a time when this coronavirus was thought to spread primarily within large droplets, emitted when someone sneezed or coughed. The idea was that a cotton covering would capture those globules, as surgical masks are designed to do, thereby protecting others from being infected. Such coverings might also provide limited protection if other people's droplets land on you.

This is good advice when cloth is all you have available, and government guidance goes on to recommend that the cloth is at least two layers thick, and forms a good fit around the mouth and nose. But almost two years into the pandemic we should be doing better.

Many coverings on the market, or made at home, do not have features such as a mouldable nose clip that help secure them to the face. As a general rule of thumb, if you feel air blowing into your eyes and your glasses fog rapidly, or if you can feel your breath escaping around a mask's edges, then contaminated air can also get in.

Masks are available that are designed to filter tiny particles and aerosols and which have been proven to be effective. So why doesn't the government simply recommend these highly effective, certified masks (known as FFP2 or FFP3 in the UK, and N95 or N99 in the US; see also footnote below)? Initially, this was because they were in short supply. This made sense at the beginning of the pandemic; the World Health Organization said it was essential to preserve limited stocks of personal protective equipment (PPE) for healthcare use.

There has been ample time to repurpose UK factories to produce masks (as has been done elsewhere in the world) or to order them from existing sources, and for those sources to scale up their manufacturing and supply chains.

But in most UK health and social care settings, such as GP surgeries and care homes, respiratory PPE has not been provided, apart from surgical masks that are not designed to form a facial seal. This is despite overwhelming evidence that standard surgical masks are not highly protective against infection.

From a public health and a humanitarian standpoint, it is ethically dubious not to inform people that more effective interventions are available. People also have a right to know that open-weave cloth coverings may provide inferior protection against infection by aerosols and microdroplets, particularly if they are poorly fitting.

People need the facts on high-efficiency masks, and need the encouragement to use them. Many of the concerns voiced about masks could easily be addressed. They can even be reworn – a fact little-known by the public. Although manufacturers recommend discarding masks after eight hours, this advice is intended for highly contaminated settings, such as an infectious disease ward.

For the public, it is in fact fine to reuse FFP masks until they break or become visibly unhygienic. Having several masks that you wear in rotation, wearing a different mask each day and then leaving it to "decontaminate", can allay concerns about buildup of pathogens. This not only cuts down the cost, it also helps with concerns about masks as plastic waste.

It is also important to choose a mask that does not have a plastic valve on the front or side, as some FFP masks do. Masks with valves let a portion of your breath out unfiltered, so they give insufficient protection to those around you.

It is time to revise the guidance. The government must encourage people to wear better masks. Countries such as Germany promote the use of high-quality masks, making them widely available and even mandating their use on public transport. It's a simple intervention that can have a big impact, and the UK needs to catch up.

Claire Horwell is professor of geohealth at Durham University and has an honorary contract with the UK Health Security Agency

This article was updated on 31 December 2021 to include guidance on avoiding – in the context of public mask wearing during the Covid pandemic – FFP masks that have valves.