PPE: the truth about your personal protection

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The phrase ‘personal protective equipment’, or PPE, was unfamiliar to many before the current crisis. Builders wearing hard hats and high visibility vests were familiar, as were police officers wearing stab vests and firefighters wearing breathing apparatus. These sights are unlikely to raise comment. But now we see members of the public in gloves and masks on a daily basis. So, what are they for and how well do they work?

The key arguments in the ‘gloves and masks for the public’ debate tend to be:

  • Who’s being protected (you, or everyone else)?
  • How effective are they (for you, and everyone else)?
  • Do they provide a false sense of security?

Let us start with some basics. We do not need to be Covid-19 experts to apply these basics to our everyday lives. Your best personal protection is provided by your skin. Normal healthy skin keeps germs out (‘germs’ is the catchall word for bacteria, viruses and other microscopic particles that cause illness). The trouble is we have essential openings to that skin: eyes, nose, mouth, anus and genitals. These opening can to some degree allow germs in, where they multiply many times over and then leave by one or more of those openings to go on and infect others. There is nothing more basic than “coughs and sneezes spread diseases” and that certainly applies here (though we had better include toilets as well!).

So we need to imagine an infected person with Covid-19 viruses coming out of them through whichever of those openings it uses (it’s a shame it doesn’t glow in the dark so that the infected person is readily identifiable). Being a respiratory illness, it mostly comes out of the nose and mouth, but don’t discount the rest of those openings in the body. The viruses will be in and around their nose and mouth, coughed onto their hand, and spread from those unwashed hands onto everything they touch. Plus, don’t forget the aerosol droplets coming out of their mouth when they talk. So how can we protect ourselves from that?

Let’s look at gloves first, as they are easier to understand. Correctly selected gloves are great for keeping the hands warm and protecting them from physical damage. The reason they’re so good at those things, is that if they fail you soon know about it and change what you do. PPE for things like germs fails to alert you to the danger; in other words, when it stops doing what you think it is doing, you don’t know about it. This leads to a false sense of confidence, where you may take more risks, simply because you think you are protected.

We know that whatever you’ve handled, your skin needs to be thoroughly washed to prevent it spreading germs into one of the openings in your skin, or onto surfaces where others can pick it up. But a glove will spread those germs just as effectively as your hand if you’re not just as careful. It is exceedingly difficult to put two gloves on, or take them off, without touching the outside of one of them. For this reason, you should avoid re-using gloves and when you’ve taken them off, you’d better wash your hands anyway in case one of the gloves was punctured.

Consider the image of the surgeon in the traditional hospital drama: lots of hand washing, followed by assistance in donning gloves to keep those gloves sterile, plus the wearing of a surgical mask. All that is not to protect the surgeon, it’s to protect the patient from the surgeon’s germs while the patient’s ‘germ-proof’ skin is opened up.

Wearing a face mask in public, as practiced commonly in Asia, follows the same principle: it’s to protect others, not yourself. A face mask that covers both nose and mouth, significantly reduces the aerosol droplets released in coughing, sneezing or talking. It helps you keep your germs to yourself. There may be an added benefit in that it can keep the hands away from the nose and mouth and in this way reduces the spread of germs onto surfaces. The material used to make these face masks has to be porous/thin enough to allow the free passage of air (so you breathe freely), while preventing the comparatively large aerosol droplets containing the germs from escaping. There is no expectation that these masks will form a seal and filter all incoming air; they won’t.

FFP3 mask. Picture courtesy © Raimond Spekking

Once you start trying to protect a person from particles the size of viruses problems arise, because viruses are very small. You need to form a seal with the mask and try to filter all incoming air. This requires a dense filtering material that is harder to breathe through and consequently the air may well pass around it rather than come through it. You’ve probably heard references in the news to the ‘FFP3’ respirator. This is not as technical as it sounds – it stands for ‘filtering facepiece for particulates’ at standard 3 (the highest standard). For a FFP3 respirator to work the wearer must be fitted for it and males should be clean-shaven. This type of mask therefore has to be worn properly and is only a short-duration item, with a maximum recommended wear time of one hour. It has another drawback in that it has a plastic exhalation valve, for breathing out through, which of course means that it does not protect others from the wearer’s “germs”. Close examination of news footage will show some NHS staff wearing two respirators, an FFP3 to protect them and surgical mask to protect others. So for anybody who has got hold of FFP3s, they may not give you much protection, especially if worn for a long time and they will not protect others from you.

Your best personal protection remains in your behaviour as instructed by HM Government; always think where your hands have been. It is not impossible that wearing face masks to protect others will become a requirement. If it does happen, follow any wearing instructions. You need to cover both your nose and mouth to have the desired effect. If you want to voluntarily obtain and wear face masks to protect others then remember that outdoors is relatively safe (whatever you are spreading is unlikely to get into anybody else), but the smaller the building or space you are inside, the more reason to protect others.

Peter Robinson is a biology graduate who spent 30 years in the asbestos industry where he taught the theory and practice of respiratory protection in asbestos and a wide range of other occupational hygiene situations.