You cannot be "too clean", millennials are being told, as public health experts attempt to debunk myths around hygiene. The Royal Society for Public Health (RSPH) said incorrect theories which became popular in the 1990s were fuelling confusion and unhygienic habits among subsequent generations.
And they called for lessons on cleanliness to be included in the national curriculum
The warning comes after organisers of Glastonbury urged festival goers to opt for “strip washes” with a flannel and soap, instead of a shower, in order to help the environment.
The “hygiene hypothesis” which became widely publicised in the 1990s argued that rising rates of allergies were being caused by "overcleanliness," suggesting children should be exposed to a wide range of potentially harmful microbes.
But experts from the Royal Society today stressed this is not the case.
They said people need diverse exposure to microbes that are mostly harmless - such as those children can find playing outdoors - but should remain vigilent about hygiene in the home.
The research found that one in six men thought there was low or no risk associated with not washing their hands after using the toilet, while one in 12 saw no need to wash their hands after handling raw meat. Around half as many women had such views.
Experts called for more “targeted hygiene” in the home, in particular cleaning surfaces, utensils and hands thoroughly during and after food preparation, and putting bedding and towels on a 60C wash. Such simple measures can cut down the risk of spreading serious infections such as listeria, e. coli or norovirus, they said.
People should also wash hands with soap and water before eating with fingers, after using the toilet, after coughing, sneezing and blowing noses and after handling and laundering dirty clothing and household linens.
Good handwashing is also essential after playing with pets, feeding them and clearing up their waste, and after putting out bin bags, the report said.
Researchers said changes in lifestyles - such as keeping children indoors, and an increasing use of antibiotics, are cutting exposure to “good bacteria” found in the natural environment.
They urged people to spend more time outdoors, and improve their hygiene in the home.
Professor Lisa Ackerley, RSPH trustee and food hygiene expert, said: "Getting outdoors and playing with friends, family and pets is great for exposure to 'good bacteria' and building a healthy microbiome, but it's also crucial that the public don't get the wrong end of the stick - this doesn't need to get in the way of good hygiene.
"Targeted hygiene undertaken at the crucial times and places is a way of preventing infection that is cheap on time and low effort, and still exposes you to all the 'good bacteria' your body benefits from.”
Professor Sally Bloomfield, from the London School of Hygiene and Tropical Medicine, said: "The problem is that we have become confused about what hygiene is, and how it differs from cleanliness.
"Whereas cleaning means removing dirt and microbes, hygiene means cleaning in the places and times that matter - in the right way - to break the chain of infection whilst preparing food, using the toilet, caring for pets etc."
A survey of 2,000 adults found that almost one in four people agreed with the statement 'hygiene in the home is not important because children need to be exposed to harmful germs to build their immune system'.
More than half also mistakenly thought keeping homes too clean was damaging.
The report said: "This is a potentially harmful belief which could lead to children being exposed unnecessarily to harmful or even life-threatening infections."
The survey also revealed "substantial public confusion" about the relationship between cleanliness and hygiene, with 61 per cent believing dirty hands from outdoor play are likely to spread harmful germs, despite there being little evidence that outdoor dirt carries harmful microbes.