Q&A with Dr Mark Kelly – Chief Scientist/Chemist at Biodx
A Guide to Popular Disinfectants

Spray Tunnels can be as dangerous as Coronavirus

With the world bursting to get out of lockdown and South Africans slowly trickling back to their workplaces, the health of their workers is uppermost on most company’s minds.

One of the ways that’s being implemented countrywide is that of human spray booths or tunnels that spray surface disinfection products, such as sodium hypochlorite or quaternary ammonium compounds (QACs), on people to counter the Coronavirus. Who wouldn’t want to be fully protected after all, BUT what are these chemicals and just what harm can they do?

As an illustrative example, we can look at sodium hypochlorite, a common household disinfectant. It is found in bleaches (eg Jik, Domestos, Clorox, Lysol) and toilet cleaners. As the name suggests one of the main components is chlorine and 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.

When you think that chlorine gas was used in the trenches in WWI this gives you an idea of the toxicity.

Warnings from CDC, WHO

With warnings issued by the CDC1 (Center for Disease Control), and WHO2 (World Health Organisation) 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.

WHO states: “Spraying individuals with disinfectants (such as in a tunnel, cabinet, or chamber) is not recommended under any circumstances. This could be physically and psychologically harmful and would not reduce an infected person’s ability to spread the virus through droplets or contact. Moreover, spraying individuals with chlorine and other toxic chemicals could result in eye and skin irritation, bronchospasm due to inhalation, and gastrointestinal effects such as nausea and vomiting.”

To add to this the WHO feels that hypochlorite at dilution safe for use on humans was not effective in killing the COVID-19 pathogen on clothing surfaces.

Calling tunnels safe is misleading

According to Dr Mark Kelly, Chief Scientist and Chemist at Biodx, “To call the use of these tunnels safe can be misleading. The primary objective of the disinfectant is to destroy the virus – that’s its job, which means it’s very toxic and can’t be taken lightly.

“What is needed is more data on exactly what ingredients and concentration amounts are used in these tunnels. You need evidence and testing certification for this because it’s acting on your clothes which are inanimate objects and currently we don’t have any coronavirus data specifically for textiles. In order to claim efficacy here it would need to meet a specific standard, particularly for the contact time and concentration used. Typically for most disinfectants to be effective against the virus it would need a minimum five minutes exposure time at 200-300 ppm concentration. The spray would have to cover and saturate a person’s entire surface area for this period to destroy everything. If all a person gets is a light, quick spray as they walk through it will evaporate in seconds, having little or no effect at all.

“In terms of the concentration amounts for disinfectant efficacy on textiles, we don’t currently have any SA standards, so would need to use EU Specifications.

“There is a huge toxicology concern with using disinfectants such as sodium hypochlorite in tunnels, and the concentration required to destroy the Coronavirus. People may claim it’s just like using HTH in your swimming pool but there’s a vast difference in the concentration here as in a pool you’re using 3ppm as a bacteriostatic (to stop bacteria from growing – not to kill it), which is an accepted safe level for skin. Also when you swim you typically don’t inhale the chlorine, whereas if you should inhale it when walking through a tunnel (and it can penetrate a mask) it will damage the sensitive mucosa in the lungs – on top of the eye & skin irritation and damage to your clothing.

When used appropriately these surface disinfectants will make an important contribution to the battle against this coronavirus. These tunnels are just not the place.

“Being responsible with social distancing, hand washing and wearing a mask is a far more appropriate way to fight this virus. An additional recommendation would be to use disinfectant footbaths at entrances and exits of high-traffic environments.

In any event, research is showing more and more that ultimately we will all get it, particularly if you’re susceptible to flu.

India Bans Tunnels

And as Burt Rodrigues Biodx CEO points out “In India they have stopped using tunnels in most public places such as airports and transport stations because of safety issues and a lack of performance information.3 The information they do have doesn’t bode well for the product being used for people. Disinfectant like this is meant for hard surfaces.

“You can safely inhale our Biodx disinfectant products at 10 mg/m3 but this amount will destroy NOTHING on an inanimate surface. Our test data indicates you would need 1,000 mg to guarantee destruction of Coronavirus.

Considering the test data is not available for applications into the atmosphere, we recommend people use caution and if possible conduct your own efficacy testing. (Biodx will make our EU test results available as soon as we receive them.) So using the allowed rate in tunnels won’t hurt people but certainly won’t destroy the virus. I would urge anyone considering installing tunnels/ booths to demand scientific proof of safety and performance from suppliers”

1 https://www.cdc.gov/coronavirus/2019-ncov/community/disinfecting-building-facility.html (Section: Alternative Disinfecting Methods)

2 https://www.who.int/publications-detail/cleaning-and-disinfection-of-environmental-surfaces-inthe-context-of-covid-19

3 https://www.dtnext.in/News/TamilNadu/2020/04/11015252/1224470/No-more-disinfection-tunnels-as-docs-warn-of-health-.vpf