Are disinfectant foggers effective at killing the coronavirus?

21 August 2020 - 06:30 By wendy knowler
subscribe Just R20 for the first month. Support independent journalism by subscribing to our digital news package.
Subscribe now
Coronafog staff use thermal fogging machines to disinfect a building. The advertising watchdog says the company's claims that it can kill the Covid-19 virus 'are currently unsubstantiated'.
Coronafog staff use thermal fogging machines to disinfect a building. The advertising watchdog says the company's claims that it can kill the Covid-19 virus 'are currently unsubstantiated'.

With the disinfectant tunnels now roundly condemned as being both ineffective and potentially harmful, the new hard sell to offices, gyms, churches and schools is the disinfectant fogger.

And with the country now in level 2, the marketing of these fogging products has been stepped up.

But many of them have not been proven to be effective against viruses, much less the new coronavirus specifically. And without sufficient contact time on surfaces, even the appropriate disinfectant won’t kill the virus, authorities and industry experts say.

Earlier this month, South Africa’s Advertising Regulatory Board (ARB) upheld a complaint that a product marketed by Meridian Hygiene as “Coronafog” falsely created the impression that it is “fogging good” at killing the coronavirus in buildings, and ordered it to withdraw the claim.

The ad watchdog said Coronafog's boasts that it can kill SARS-CoV-2, the virus which causes Covid-19, and that its product and process are effective against the coronavirus, “are currently unsubstantiated” and thus misleading.

Meridian Hygiene told the ARB it had looked for guidance from the US Environmental Protection Agency (EPA) about disinfectants it could use in its fogging machines to combat SARS-CoV-2.

“The EPA expects any disinfectant to kill SARS-CoV-2 (coronavirus 2) if such a disinfectant is effective against other 'hard-to-kill' viruses [or] ... other human coronaviruses,” it said.

Coronafog submitted the results of tests done in 2011 on Beyond Green’s San-A-Med, the water-based, non-chemical disinfectant it uses in its fogging machines, but the ARB said the company had not submitted unequivocal verification from an independent and credible expert to support its arguments and assumptions.

Traditional disinfectants contain alcohol, chlorine or QACs (quaternary ammonium compounds).

“It is also unclear why studies conducted in 2011, which involved soaking the relevant pathogens by spraying them repeatedly until 'thoroughly wet', would support [Coronafog's] 'thermal fogging' technique, which disperses the disinfectant as a 'dry fog',” said the ARB.

'99.99% effective'

Ironically, conclusive proof that Beyond Green San-A-Med is effective in killing SARS-CoV-2 has since been obtained.

Francois Viljoen, co-founder of Pretoria-based disinfection services company GermCure, which sells Beyond Green San-A-Med, told TimesLIVE that samples of the SARS-CoV-2 virus were imported from China in order to prove the efficacy of both its San-A-Med and San-A-Safe products.

The samples were tested by a renowned scientific research laboratory in Pretoria, which last week released laboratory reports confirming that both products “showed an effectiveness of 99.99% against SARS-CoV-2 virus” in its tests.

Francois totally agrees with the ARB’s finding the product is only half the story - the way it’s applied is crucial to its efficacy. His company uses electrostatic sprayers as a method of application.

In her review of evidence-based environmental cleaning and disinfection guidance in South Africa, published in June, Prof Shaheen Mehtar of Infection Control Africa Network and Stellenbosch University pointed to World Health Organisation advice that: “In indoor spaces, routine application of disinfectants to environmental surfaces by spraying or fogging (also known as fumigation or misting) is not recommended for Covid-19.

“Spraying disinfectants can also result in risks to the eyes, respiratory or skin irritation and the resulting health effects.

“Spraying or fogging of certain chemicals such as formaldehyde, chlorine-based agents or QACs is not recommended due to the adverse health effects on workers in facilities where these methods have been utilised.”

According to the EPA, a disinfectant product’s safety and effectiveness is largely dependent on how it’s applied.

“If a pesticide product’s label does not include disinfection directions for use with fogging, fumigation … or electrostatic spraying, the EPA has not reviewed any data on whether the product is safe and effective when used by those methods,” said the agency.

It added that it would expedite applications it has received for using an electrostatic spray to disinfect large indoor spaces to reduce the risk of exposure to the SARS-CoV-2 virus that causes Covid-19.

'An easy sell'

Electrostatic sprayers work by positively charging the antimicrobial liquid as it passes through a nozzle, and those droplets are then attracted to negatively charged environmental surfaces, allowing for improved coverage on hard, non-porous environmental surfaces.

“No matter how you apply a disinfectant,” says Viljoen, it needs adequate surface contact time.

“When painting a room, if you need five litres of paint, you are not going to do the job correctly with just one or two litres. Disinfectant works the same. You must deposit enough on all surfaces to achieve necessary contact time and it needs to remain wet or damp for the prescribed contact time - usually a few minutes -  to be effective.”

The disinfectant must be in the correct concentration, or it won’t work either, Viljoen said.

“If you’re being quoted less than R1 a square metre, you’re unlikely to be getting a professional, effective service.”

Unless you have a lab report proving that your product works in the way in which it is applied, you should not make that claim.
Francois Viljoen, GermCure 

“Dry fogging” sounds appealing to companies, Viljoen said, “so it’s an easy sell”.

“The sudden, intense demand for disinfection services after the outbreak of the Covid-19 pandemic led to many people marketing themselves as  SARS-CoV-2 disinfection specialists. But most rely on the assumption that their products and application methods work,” said Viljoen.

“Unless you have a lab report proving that your product works in the way in which it is applied, you should not make that claim.”

Any disinfectant product sold in South Africa needs to be approved and registered with the National Regulator in Compulsory Specifications (NRCS).

Some fogging companies were using products which have proved effective against bacteria, but not viruses, said Viljoen.

“They claim to fog their ‘safe’ disinfectants to ‘help curb’ the spread of Covid-19, but they are using bacteriacidals - products which kill bacteria, but not viruses.

“And why do we see people wearing hazmat suits and other forms of excessive PPE while fogging disinfectants? I think the answer lies in the fact that the disinfectants that they fog are not as safe and environmentally friendly as they claim.”

Jumping on the bandwagon

“Killing bugs with smokes and mists is a very specialised business,” says Hannes Hattingh, co-owner of the Durban-based independent biosecurity chemical manufacturing company ManChem. The company is the largest manufacturer of poultry disinfectant in Africa.

“It took us eight years to develop our patented smoke generator - and we do the application ourselves,” he said.

“A lot of people have jumped on the fogging bandwagon, but from what I’ve seen, much of what they are doing is ineffective.

“I’ve seen a photo of a tiny little fogger in a Pietermaritzburg church, emitting a wisp of smoke, with guys standing by in hazmat suits. That’s ridiculous, but there’s a lot of that happening.”

The best approach, with schools for example, is to follow the advice of the US Centres for Disease Control (CDC): wipe door handles, desks, light switches - anything that will be touched by hands - with a detergent which has been proven to be effective in killing the coronavirus.”

“If you want extra protection, then do fogging as well - but clean and disinfect the traditional way first,” said Hattingh.

Questions to ask a disinfection service provider:

  • Is there any scientific proof that the product you are going to use is effective against any of the previous human coronavirus strains, or specifically against SARS-CoV-2 - or against any virus?
  • Request a lab test or certification.
  • What contact period is required to eliminate the virus/pathogen and how do you ensure you achieve this contact period?
  • Is the product a virucidal or only a bacteriacidal?
  • Is the product safe to use around animals and people, especially children?
  • Does the material safety data sheet (MSDS) state that the product does not contain any hazardous/toxic ingredients?
  • Does the product produce any volatile organic compounds or toxic fumes?
  • Is the product carcinogenic?
  • Do you require any PPE when spraying or fogging the product?
  • If so, why and what PPE needs to be worn?


GET IN TOUCH: You can contact Wendy Knowler for advice with your consumer issues via e-mail: or on Twitter: @wendyknowler.

subscribe Just R20 for the first month. Support independent journalism by subscribing to our digital news package.
Subscribe now