Cleaning has never played a bigger role in our lives than it does today thanks to Covid-19. Whether it's wiping down workplace surfaces or disinfecting supermarket trolley handles, we're doing it all more.
And a 2021 US study showed that more than 40 percent of 2000 respondents now identified as germaphobes.
However, a New York Times science journalist recently spoke to experts who said that many common cleaning practices aren't all that effective, while there are others that we shouldn't even be doing in the first place - like religiously disinfecting the bathroom.
Photo: 123rf
Listen to the full interview here
New Zealand’s own expert on the matter, microbiologist Siouxsie Wiles tells Jim Mora the problem is often we’re disinfecting when just a good clean will do the job.
Cleaning removes dirt and microbes from a surface, while disinfecting kills what’s on the surface, which can include bacteria and viruses, she says.
“The question is are you trying to physically remove something from a surface or with disinfecting are you really just adding that solution to the surface, but that dirt is still there?”
Although chemical sprays and wipes often claim they kill 99 percent of bacteria and viruses, those lab tests are often done on small samples, she says.
“[Bacteria] grow very fast, so if you haven’t actually killed all of them, and some are left there on the surface, they can actually just continue growing. So often the disinfecting, if you are going to do it, has to come with cleaning as well.”
The New York Times article on cleaning suggests you don’t need to disinfect your kitchen benchtops every day, unless you’ve been working with raw meat, and your bathroom probably only needs it if a household occupant has an infection that spreads through stools.
“Really disinfection is for when you know you’ve got sick people around so there’s more likely to be nasty bacteria or viruses that have been spread around about the place,” Dr Wiles says.
Also, studies that identify where the most germs are around us might have us reaching for the disinfectants more often, but Wiles says it’s not always clear whether these are the “bad” microbes or not.
“Our environment is completely full of microorganisms, and the vast majority of those are just doing their thing, in fact often they’re taking up space that could actually be taken up by nastier microbes. So, you really kind of don’t want to get rid of everything.”
Microbiologist Siouxsie Wiles Photo:
One of the concerns of overusing certain disinfectants is that chemicals like quaternary ammonium compounds – often found in household sprays – release fumes, Dr Wiles says.
“It’s just really, really important that we ventilate a place as well.”
More importantly, Dr Wiles says we can make bacteria more resistant if we don’t use these agents as directed on the labels, including following the required time for the disinfectant to work.
“They can change and become much more difficult to kill with the disinfectants, actually it can also cause changes in them that might make them more difficult to kill with for example things like antibiotics, which we need when we have an infection.
“Interestingly, the more sort of natural products probably take longer than the chemically sounding ones, but we know that every product is different and also every surface is different too.”
Although some studies have shown the Omicron variant of Covid-19 can survive longer on surfaces than previous variants, Dr Wiles notes PCR tests can detect even non-viable amounts which can’t cause infection.
“So, I’m not quite sure if that has been clarified yet [in the studies], whether they actually still are surviving and able to cause an infection.”
Soap is very effective against the SARS‑CoV‑2 virus, but the majority transmission of Covid-19 happens through the air, she says.
“While it’s still very, very important for people to wash their hands because that will certainly prevent all sorts of infectious diseases, for Covid, it’s actually about the air.
“The sort of obsession with ‘we need to spraying antiviral products everywhere’, I think it was understandable at the beginning of the pandemic when we were all very focused on surfaces.
“Now we know how this virus is transmitted, it’s much more about how do we maintain good air, and part of that is why people, like me, are still banging on about everyone wearing masks.”