Questioning the viability and efficacy of disinfectant

Repeat the ATP tests after fogging and again over several weeks, or months, as appropriate.

Normal practice is to test for ATP before and after fogging. We have carried out multiple trials at our own offices and at client sites. These have shown a very dramatic decline in ATP counts.

It’s also significant that repeat tests several weeks after fogging indicate that the biocide prevents much of the usual contamination or at least limits the rate at which cultures redevelop. Our tests have shown that the chemical continues to act as an effective bactericide and virucide after application to prevent future outbreaks. Chemical suppliers claim the residual efficacy of a fogging agent can extend into months and longer. But this will depend on exposure to re-contamination and other factors.

To give an example, after half the pupils in a community school were struck down with what proved to be the Norovirus, we carried out an extensive fogging programme. ATP testing showed that the treatment had been effective. Subsequent random tests afterwards indicated that counts were still very low – with one exception, a cuddly toy in the infants’ play area. While there was no reason to assume that harmful bacteria were responsible, steam cleaning of the toy was recommended.

The drawbacks of fogging

We see bio-fogging as a highly effective weapon in our armoury of cleaning techniques, but it’s not a silver bullet.

In the first instance, a thorough cleaning is required in advance of fogging or its impact could be curbed. The biocide vapour needs to make contact with the microorganisms on a surface to kill them. If dirt, debris, wet patches or some other material are covering parts of a surface, then these areas may not be sanitised. So we recommend that fogging is carried out in conjunction with a deep clean.

FMs also need to consider measures such as air sanitisers that use UV light and other techniques to decontaminate and deodorise air in washrooms and elsewhere.

Another issue is cost. Fogging is not a cheap option. The chemicals are more expensive than common cleaning solutions. It also requires an investment by the cleansing services provider in fogger machines, ATP meters and in monitoring and training.

But we believe that fogging is costeffective as a sanitisation technique. Not only is it relatively quick, causing minimal disruption, the results are immediate and the benefits are potentially significant and long-lasting.

The increasing trend of erecting sanitising booths/disinfectant tunnels at the entrances of transport hubs, shops, malls and workplaces to combat COVID-19 infections begs more questions than answers.

According to the World Health Organisation (WHO) the spraying of individuals with disinfectants (such as in a tunnel, cabinet, or chamber) is not recommended under any circumstances. This practice could be physically and psychologically harmful and would not reduce an infected person’s ability to spread the virus through droplets or contact. Even if someone who is infected with COVID-19 passes through a disinfection tunnel or chamber, as soon as they start speaking, coughing or sneezing they can still spread the virus.

Questioning the viability and efficacy of disinfectant tunnels and spraying outdoor areas

The toxic effect of spraying with chemicals such as chlorine on individuals can lead to eye and skin irritation, bronchospasm due to inhalation, and potentially gastrointestinal effects such as nausea and vomiting.

In outdoor spaces, WHO does not recommend large-scale spraying or fumigation in areas such as streets, transport hubs or open market places for the COVID-19 virus or other pathogens. Streets and sidewalks are not considered as routes of infection for COVID-19. Spraying disinfectants, even outdoors, can be noxious for people’s health and cause eye, respiratory or skin irritation or damage.

When and where is fogging justified?

The most obvious scenario is the response to an infectious outbreak. But given the benefits of sanitisation, and the heavy cost to organisations and people in lost output, disruption and welfare when infection spreads, we recommend having areas fogged twice a year to achieve a good level of protection.

That advice is especially useful where people may be more vulnerable to bacterial or viral infection. This would include the infirm in care homes or children in nurseries, but also other groups, such as university students in halls of residence.

Fogging and other sanitisation measures should also feature in contingency planning for the winter season and other times of heightened risk.

All of us responsible for managing or cleaning the buildings where people work, study, visit or live need to be prepared to combat a germ attack, preferably by repelling it.

For more information visit: www.nviro.co.uk

This practice will be ineffective since the presence of dirt or rubbish for example, inactivates the disinfectant, and manual cleaning to physically remove all matter is not feasible. This is even less effective on porous surfaces such as sidewalks and unpaved walkways. Even in the absence of dirt or rubbish, it is unlikely that chemical spraying would adequately cover surfaces allowing the required contact time to inactivate pathogens.