Explainer: What is deep cleaning and how does it work?

Kezeng Wangdi and Lydia Utting form part of the team of deep cleaners at Lyneham High School. Picture: Sitthixay Ditthavong
Kezeng Wangdi and Lydia Utting form part of the team of deep cleaners at Lyneham High School. Picture: Sitthixay Ditthavong

Cleaning has taken on an even greater role during the COVID-19 pandemic as the number of cases continues to increase.

With the discovery of more coronavirus clusters in locations ranging from aged-care facilities and schools, to restaurants and other businesses, many have had to undergo deep cleaning in an attempt to remove traces of the virus.

In some areas, it has already become a common sight to see cleaners in head-to-toe PPE. As health authorities continue to respond to new clusters, the focus on deep cleaning is likely to increase.

What is deep cleaning?

While cleaning normally focuses on removing visible signs of mess through vacuuming, dusting and wiping things down, deep cleaning goes one step further.

Deep cleaning involves the use of disinfectant and other chemicals to remove any traces of germs and viruses, including coronavirus.

Part of deep cleaning also involves wiping down every surface in a venue, regardless of whether it has come into direct contact with an infected person or not.

A particular focus is high-frequency touch points, such as light switches, door handles, taps and areas like computer terminals or communal kitchens in office spaces. While high-grade disinfectants are used as part of deep cleaning, other chemicals can also help to remove traces of the virus.

Anthony Bailey, ACT Education Directorate senior director of school cleaning services, said a fine-mist spray was also used as part of deep cleaning efforts in Canberra schools.

"With the fine-mist spray, the chemical settles in areas you can't normally reach," Mr Bailey said.

"It's unlikely people are touching those surfaces, but it's all about elimination.

One of the ACT's schools, Lyneham High School, required deep cleaning in March after a student attended the campus while potentially contagious with coronavirus.

Mr Bailey said swab tests of surfaces for traces of coronavirus were also carried out before students and staff members could re-enter the school.

How long can coronavirus stay on surfaces?

One of the main ways coronavirus has been able to spread is through being picked up by humans after they come into contact with the virus on surfaces. Research is being carried out in a number of places on how long exactly the virus can linger on surfaces and lead to further infections.

Early findings have determined strains of COVID-19 can stay alive for several hours or even days, depending on the type of surface it lands on.

According to a recent study from the New England Journal of Medicine, the virus can last for four hours on copper surfaces, while it can stay on cardboard or paper for 24 hours and up to three days on plastic and stainless steel.

A similar study published in The Lancet had slightly different findings, with the virus lasting for three hours on tissue paper, while traces were still detected on cloth and wooden materials for two days.

Associate professor at the Australian National University medical school, Sanjaya Senanayake, said the Lancet study also found the virus could stay on surfaces such as surgical masks for up to one week after they were worn.

"The two studies were slightly different in the types of materials that were used, but clearly the virus can survive on surfaces for some time," associate professor Senanayake said.

"Maybe after half an hour on a surface, there's a lot more virus on it, and therefore people are more likely to be infected if they come into contact.

"By the seventh day, the virus might still be around on surfaces, but may not be enough to cause an infection."

How does deep cleaning kill coronavirus?

At its core, deep cleaning is about attacking the virus at every possible location it could be in a building.

However, for a virus that's devastated nations around the world and locked down cities across Australia, associate professor Senanayake said COVID-19 was remarkably easy to kill.


"It's an enveloped virus, meaning it's got an outer covering and it's very susceptible to things," he said.

"Despite it being this terrible thing that's caused a pandemic, it's easy to kill with things like standard detergents as well as soap and water."

Using things like detergents might be enough to kill off the virus, but associate professor Senanayake said using just disinfectant or chemicals on their own might not have the desired effect.

"If you put just disinfectant on those areas, some of the virus particles might be able to hide," he said.

"Surfaces should be cleaned with detergent first and then disinfected after that with something like 70 per cent alcohol or bleach."

It should also be noted that any cleaning of surfaces suspected of having traces of coronavirus should be done with personal protection, such as a mask.

Is coronavirus leading to more deep cleaning?

The short answer is yes.

Some in Canberra's cleaning industry said more and more people had requested deep cleaning at offices and other large indoor areas in recent weeks, even if there had been no confirmed cases of coronavirus associated with them.

Mint Cleaning Group manager Dora Rodriguez said places such as offices had requested more cleaning services.

"People want to make sure that everything is sanitised and disinfected to prevent the spread of germs," she said.

"The frequency of deep cleaning has been a big change, but it's been for hygienic practices, rather than clearing any traces of coronavirus."

This story Explainer: What is deep cleaning and how does it work? first appeared on The Canberra Times.