Disinfection tunnels are a bad idea, warns top chemist

Disinfection spray booths and tunnels may do more harm than good, a prominent South African chemist has warned.

Many companies returning to work under level 3 workplace restrictions are using a variety of spray and sanitiser interventions to limit the spread of coronavirus.

However, Dr Mark Kelly, chief scientist at Biodx Biological Chemical Technologies, has questioned the efficacy and safety of the most commonly used chemicals, including sodium hypochlorite.

Kelly referred to recent health alerts highlighting possible adverse side-effects of chemical spraying.

“Even watered down, this can still do massive damage, especially when this is more than just a one-off experience, as in entering and exiting the workplace once or even more times a day.

“With warnings issued by the [US regulator] Centers for Disease Control, companies and institutions must take note before showering their staff with what could potentially cause irreversible damage to the mucosa of lungs – the very area affected by coronavirus, as well as the eyes and skin. They also warn that such exposure could cause nasal irritation, sore throat and coughing,” he said.

Kelly added: “The World Health Organisation feels that hypochlorite at dilution safe for use on humans was not effective in killing the Covid-19 pathogen on clothing surfaces.

 “To call the use of these tunnels safe can be misleading. The primary objective is to destroy the virus – that’s its job, which means it’s very toxic and can’t be taken lightly.”

Kelly told Times Select the coronavirus pandemic had sparked huge interest in disinfection products, raising questions about the efficacy of registered products.

“The [spray] tunnels haven’t really been shown to be effective, and we’ve not seen any independent data giving comment on how effective they are,” he said.

By contrast, the measured use of disinfectant on hard surfaces had a proven track record, with in some cases a 99.9% success rate, Kelly said.

A cautionary note on the CDC website recommends surface sanitisers rather than tunnels: “CDC does not recommend the use of sanitising tunnels. There is no evidence that they are effective in reducing the spread of Covid-19. Chemicals used in sanitising tunnels could cause skin, eye or respiratory irritation or damage.”

Biodx develops a range of antimicrobial and antiviral technologies using a natural citrus extract. The company says its products contain no harmful chlorine or ethanol, which may be harmful to health if used inappropriately.

His comments come a week after renowned epidemiologist Prof Salim Abdool Karim told a health media briefing that “human disinfection” – particularly used in tunnels – was not part of the government’s “coronavirus protection toolbox”.

“This should simply not be permitted. Spraying humans with chemicals and putting humans through fumigation tunnels is potentially dangerous. It can damage the eyes, it can cause skin rashes and affect breathing. There is little or no evidence of the safety of the chemicals being used.

“To cap it off, it’s not just that these are potentially harmful, it’s that there’s no discernible benefit for coronavirus prevention.

So what we have in these fumigation tunnels and human spraying is a harmful pracitice that has almost no benefit,” Abdool Karim said.

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