advertisement

Infectious Diseases

Updated 12 August 2020

Considering a valve mask? You might want to read this first

With so many options on the market, you might be tempted to choose a mask with a built-in valve for easier breathing. But does this increase your risk of spreading Covid-19?

  • Non-medical face coverings are now mandatory in public spaces
  • As these masks are not regulated, they vary in design and fabric
  • Some reusable masks have built-in filters, which may put others at risk

With masks mandatory in public spaces, people want to find an option that offers them comfort and maximum protection.

While there are currently no standard regulations for the manufacture of non-medical cloth masks, there are some designs and fabrics that are more effective than others. One study, previously discussed on Health24, has shown that multi-layered, thick materials are better than single-layered face coverings. Another study has shown that the design of a mask also matters. Cone-shaped masks offer better protection than a normal scarf or bandanna.

The golden standard for face masks is the medical-grade N95 filter mask. However, these are specialised and should be reserved for healthcare workers. But as masks crop up from retailers, we see all sorts of material masks – some of them also with filters and valves. We might wonder how effective these filters are – and if the valves ease the breathing of the user, could they still offer protection to the people around us?

Filters vs. valves

Not all masks are created equal. The N95 filter masks are made with a built-in filter to filtrate airborne particles. According to the US Food and Drug Administration (FDA), they are designed to serve as protective devices in certain industries, including healthcare settings. The edges of these masks are designed to form a seal around the nose and mouth. They are regulated and tested for fluid resistance, filtration efficiency (particulate and bacterial filtration efficiency), flammability and biocompatibility.

Ideally, these masks should not be reused as the filter gets soiled. Unfortunately, with worldwide PPE shortages, this remains a problem, and researchers are investigating ways to disinfect and reuse N95 masks.

But as the use of masks become compulsory, we see several manufacturers selling masks with built-in valves to increase wearer comfort, and while some of them also have built-in N95 filters, they do not offer the same level of protection as medical-grade PPE.  

Valve masks may look sophisticated and offer the benefit of being more comfortable, but the valve design only allows the air you inhale to be filtered – not the air you exhale, which can escape through built-in vents. Medical-grade N95 masks don’t have these vents, which prevents the virus from being carried in exhaled droplets.

That means, if you are a SARS-Cov-2 carrier, those valves will not protect other people against your respiratory droplets.

Public health warning

While many guidelines simply stipulate that one should wear a fabric face covering, the San Francisco Department of Public Health issued a warning via their Twitter account that these non-medical N95-masks with valves will not be permitted, because “they are not safe and might propel your germs further”.

Their original public health order also stated that masks with one-way valves were not permitted. “Valves of that type permit droplet release from the mask, putting others at risk,” the order stated.

Experts agree. According to Dr Ali Raja, executive vice-chair of the department of emergency medicine at Massachusetts General Hospital and an associate professor at Harvard Medical School, these masks might offer the wearer protection, but not the people around them, unless they're also wearing masks.

“Any mask with a one-way valve is only going to protect the person wearing it. It won’t protect anyone around that person from potential exposure to virus particles they exhale,” he told Healthline. “It may give the people surrounding them a false sense of security.”

Filters need replacement

Another caveat regarding N95 masks with built-in valves, is the fact that the filter needs to be discarded or replaced on a regular basis.

According to the Minnesota Department of Health, N95 filters are disposable and cannot be cleaned. It also states that these masks should be discarded after caring for a patient with an illnesses that can spread through the air (such as Covid-19).

Many non-medical masks with built-in filters are sold as reusable. These filters, however, need to be discarded as they become less effective after a while. However, replacements can be purchased and placed inside built-in filter pockets.

Protecting others

It’s vital to understand that wearing a mask or face-covering isn’t only about protecting yourself, but also protecting others when in public. As many cases of Covid-19 are asymptomatic, it’s possible to come into contact with infected people without being aware of it.

If you are concerned about people around you wearing valve masks, protect yourself by wearing a multi-layered covering made of tightly-weaved thick cotton.

I bought one of these masks – should I throw it out?

Money is tight and medical research changes the way we view Covid-19 almost daily, and if you’ve invested in some of these valve masks but are concerned that they don’t offer suitable protection to those around you, keep them, but carefully consider where you wear them.

No mask on its own offers 100% protection, and the infection risk increases when a group of people are inside a badly ventilated indoor area. If you are outdoors in a park, where physical distancing is more feasible than in a shop, these valve masks could be fine if you're able to maintain your distance from other people. But consider wearing a “normal” fabric mask without these air vents when you're indoors where it’s hard to maintain your distance from others.

Bear in mind that although no mask can guarantee 100% protection if it’s not coupled with hand hygiene and physical distancing – but there is sufficient evidence that masks can slow down the spread of SARS-CoV-2.

READ | Masks and Covid-19: The latest guidelines

READ | Here are the best and worst materials for face masks

READ | Running with a mask: What you should know

Image credit: Getty Images