We know that winter is on its way, not only with its usual cacophony of bugs and illnesses, but this season with a growing number of new Covid cases, according to daily government figures and projections.
While we have become more used to wearing a face mask – thanks to several studies that have proven their effectiveness at stopping the spread of the virus and increasing government legislation on where we need to wear it – what many of us haven’t been aware of is how our mask wearing might be affected by the wet and windy winter weather.
The World Health Organisation and Public Health England have both warned that face masks need to be changed when they get damp. “All masks should be changed if wet or visibly soiled,” the WHO states. “A wet mask should not be worn for an extended period of time. Replace masks as soon as they become damp with a new clean, dry mask.”
In addition, the US-based Centres for Disease Control and Prevention (CDCP), adds: “A wet mask may make it difficult to breathe.”
Masks are currently not compulsory outdoors in the UK, unlike in Italy, which is expected to introduce a new rule along with many cities in France. But increasingly Britons are keeping their masks on between trips on public transport, and to shops and cafés. With the rise of the wet weather, it is leading some experts, including Professor Tim Spector, who leads the Covid symptoms app project, to question if the public know enough about the effectiveness of their masks once they’ve been exposed to the elements.
In general, masks are thought to be effective in stopping the spread of the virus, as they halt respiratory droplets expelled when a person sneezes, coughs or even talks. A study by researchers at the University of Edinburgh found that someone standing two metres from a coughing person who has no mask is exposed to 10,000 times more droplets than someone half a metre from a coughing person who is wearing one.
But a wet mask could be different. “A wet mask may be less effective, likely due to low filtration capacity,” Dr Abrar Ahmad Chughtai, an epidemiologist at the University of New South Wales, Sydney says. “Some lab-based studies showed that filtration effectiveness of dry masks was better compared to wet cloth masks. But there is no clinical data to support this. We need to do more studies.”
Other scientists think there is still merit in wearing a mask, even in the rain. Dr Lucia Bandiera, who was part of the team of Edinburgh researchers into the face covering study, says she thinks that even wet fabric coverings can still help prevent the spread of the virus. “Our research focused on indoor tests of the effectiveness of face coverings at blocking the spread of large respiratory droplets, but I know our results hold in case of prolonged use of the face covering – for example, the accumulation of liquid on the inner side of the covering – therefore I don’t have reasons to believe wet weather would alter the effectiveness of masks.” But she says that she does not think any other research team has investigated the effectiveness of damp masks.
Marc Donovan, Boots UK pharmacist, adds: “It’s important to differentiate between a face covering, such as a homemade or bought fabric one, and disposable surgical masks. When the latter get wet, they get more permeable and not as effective at stopping the virus coming out of someone’s nose and mouth and into the air. If the surgical masks do get wet, they should be disposed of and a new one used.”
Donovan adds that to be safe as we go into autumn and winter, “people should consider bringing a spare mask in their pocket.” Other advice includes keeping masks stored in clean, waterproof ziplocked bags.
Different types of mask
What kind of mask you wear counts, too. While those of us not working on the front line don’t need medical-grade N-95 masks to protect ourselves, many of us – especially those with homemade coverings – might not be wearing enough layers. The WHO recommends a three-layer face mask, consisting of an inner layer of absorbent material such as cotton, a middle layer of non-woven material such as polypropylene and an outer layer of non-absorbent material, such as polyester or polyester blend.
The overriding message, however, is one of confusion. Chughtai believes that the public needs more guidance. “Daily, I see many people who do not cover their nose while wearing a mask, or who touch their mask frequently, or put a used mask back in their pocket – including the President of the United States, who did that when he returned to the White House. People also need to know that they need to wash their cloth masks daily.” The WHO recommends washing fabric masks at least once per day, with laundry detergent and water above 60°C.
Scientists are keen to underscore that face coverings are not enough to fight off a winter attack of coronavirus. In a paper by the Royal Society and the British Academy, it urges that “face masks and coverings cannot be seen in isolation but are part of ‘policy packages’” that includes other personal measures such as hand washing, the use of sanitisers and social distancing.
Donovan says that an upshot of more people wearing masks and washing their hands is “that we should see a reduction in the common cold this year; face coverings stop the transmission of any respiratory virus by up to 90%.” This winter the NHS is conducting a massive drive to offer flu vaccinations to a record number of 30 million people, as new Public Health England research suggests that people infected with both flu and coronavirus are more at risk of severe injury and death. “People have been very keen to get their flu jab early this year, Donovan agrees. “It’s really good to see people taking all the precautions they can.”
Some manufacturers have stepped up their offering to help combat the spread of the virus over winter. AusAir, which developed a mask for Australians suffering from the bush fires, has just released a mask with a washable outer layer, breathable stainless steel exhalation valves and a copper-infused carry case that kills bacteria, too (£60; shopausair.com or selfridges.com).
Meanwhile Breathe Happy’s reusable respirator face mask has eco-friendly, replaceable filters that cut out over 95% of the bacteria in the air. The silicon mask (which is not PPE) needs to be sterilised every seven days, and filters replaced weekly. £24.99