WATCH: This UV video shows how soap really kills germs
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London - Is your hand-washing technique effective? Good Health used a special UV camera to test methods - from a quick "rinse and shake" to more than the advised 20 seconds — to find out.
First our journalist rubbed on a gel known as Glo Germ, which simulates how germs cling to your skin. The gel is clear but glows under UV light and contains particles the same size as germs such as coronavirus. The whiter the hands in these pictures, the dirtier they are — and the darker they are, the cleaner.
The most important part of hand washing is using soap — it’s sticky, so you have to wash it off. Soap doesn’t kill bacteria, it gets rid of them: one end of the soap molecule attaches to water while the other end attaches to dirt (which is where the germs will be). Lathering with soap also enhances the rubbing action. Hygiene expert Lisa Ackerley said: "Scrub the fingertips against your palms to clean under the nails."
Around seconds is roughly how long you should wash for, according to the World Health Organisation. "You need that time to clean all the little bits of your hands," said hygiene expert Lisa Ackerley.
The Centres For Disease Control and Prevention in the US suggests washing for up to 30 seconds. There is a visible difference — there are even fewer white areas.
The crescents of germs around the cuticles in the 20-second picture have all but gone — though amazingly, there is still a trace. So should you be washing for longer? It could remove the rest of the germs, but "it’s getting rid of the majority that matters", Dr Val Curtis, a public health expert at the London School of Hygiene & Tropical Medicine, said.
Research suggests that up to a quarter of us only briefly rinse our hands, but as this video shows, that is not enough. The rinse and shake doesn’t achieve much; after running your hands under the tap for three seconds, hands show up as glowing white under the camera — suggesting most of the germs have been left there.
Six seconds is the average length of time people spend washing their hands. But this is not long enough to remove germs effectively — there is still a high concentration on the backs, around the wedding ring and under the fingernails.
Washing the hands for slightly longer has reduced the white areas compared with rinse and shake — no doubt because this time the hands have been dried with a towel. And damp hands transfer germs much more easily so drying them is key.