(Image credit: Getty Images)
Many of us spring clean as the weather warms. But is there a house that is too clean? Could a little dirt do us any good?
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With spring approaching in the northern hemisphere, many of us are ready to open the windows, get out the cleaning supplies, and get all the dust, grime, and dirt out of our homes.
But what is the importance of having a clean house for our health? Does deep cleaning help prevent infections and protect us from disease? Experts say we need to be careful not to confuse cleanliness with good hygiene.
The Covid-19 pandemic increased household cleaning as people tried to keep the virus at bay by disinfecting every inch of their home. This was exacerbated by the World Health Organization’s early warning that the virus could spread through contaminated surfaces, called fomites. Subsequent research concluded that the surfaces posed a low risk of disease transmission.
Sally Bloomfield, chair of the International Scientific Forum on Home Hygiene and honorary professor at the London School of Hygiene and Tropical Medicine, fears the pandemic has led many people to adopt unnecessary cleaning habits. These can include things like obsessively scrubbing their floors, instead of focusing on good hygiene practices that help prevent the spread of disease.
“People are obsessed with cleanliness as a way to protect themselves against germs,” says Bloomfield. “It’s somewhere in our DNA that we associate cleanliness with health… We’ve evolved to have a disgust reflex and avoid unpleasant or smelly things.”
But cleanliness and hygiene are not the same thing, she says.
Current health advice suggests people should wash their hands after handling pets, for example (Credit: Getty Images)
“Cleanliness consists in obtaining the appearance of [an area] looking clean, vacuuming or wiping it down,” she says. “But hygiene is about protecting yourself from harmful germs.
These include pathogens such as norovirus, influenza, Covid-19 and salmonella, says Bloomfield.
“Hygiene is a set of actions, not a state, that you perform when needed, rather than at a prescribed time,” says Bloomfield. “It’s about stepping in at key moments.”
We should all practice “targeted hygiene” in our daily lives and recognize when harmful microbes are likely to spread, says Bloomfield. For example, when we handle raw food, use the toilet, touch pets, blow our nose or throw garbage.
Nine key moments for targeted hygiene
The International Scientific Forum on Household Hygiene has defined nine key moments when it is vital to practice good hygiene in our daily lives:
● During food handling
● Eating with your fingers
● Go to the bathroom and change a diaper
● Cough, sneeze and blow your nose
● Touching surfaces frequently touched by other people
● Handling and washing “dirty” clothes and linens
● Take care of pets
● Handling and disposal of waste
● Caring for an infected family member
The belief that cleanliness and hygiene are the same has persisted since the late 1980s, when epidemiologist David Strachan postulated the hygiene hypothesis. He argued that early childhood exposure to germs and infections helps build children’s immune systems and protects against allergies.
The increase in childhood allergies and asthma in the late 20th century was linked to reduced children’s exposure to microbes due to shrinking family sizes, limited interaction with animals, and higher cleanliness standards, according to Strachan.
But scientists now argue that there is no evidence showing that cleanliness is linked to the development of allergies.
Graham Rook, Emeritus Professor of Medical Microbiology at University College London (UCL), argues that the hygiene hypothesis should instead be reframed as “the old friends hypothesis”. He argues that exposure to “old friends”, non-infectious organisms, which have been around for much of our evolutionary history, is actually what trains the immune system not to overreact to harmless microbes, rather than childhood infections or the cleanliness of your home. to grow.
Since the 1980s, some scientists have believed that playing in dirtier environments helps create a healthy immune system in children. (Credit: /Getty Images)
We are born with a fully formed immune system that needs to be programmed,” says Bloomfield. “Programming is done by ‘old friends’. [They are] teach the immune system not to react to things like pollen and food allergens, which are perfectly harmless.”
A child’s susceptibility to developing allergies therefore has nothing to do with cleanliness, but rather with their exposure to different types of microorganisms through their gut, skin and the air they breathe, according to scientists. (Learn more about how we can prevent food allergies through early exposure.)
In a 2021 study, Rook and Bloomfield concluded that we’re not too clean for our own good.
Children receive all the microbial inputs they need to develop a healthy immune system through vaccines, their natural environment and the beneficial microbiota they get from their mothers during childbirth, they said.
“We certainly need to meet the microbiota of our mothers and the natural environment, and not doing so certainly contributes to immunoregulatory disorders such as allergies, because these organisms put in place the mechanisms that regulate the immune system,” says Rook. But cleaning the house “does not necessarily reduce the child’s exposure to the mother or to nature”.
“Targeted hygiene practices at key risk times and sites can maximize protection against infection while minimizing any impact on critical microbial exposures,” the study says.
“You can’t keep your house hygienic. If you wanted to do that, you’d have to put it in a sterile box,” says Bloomfield. “But if you step in at key times, you’ll face most of the risk.”
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