I wrote a post a while back on what I saw as “decontamination theater”: the shots (originally from China) of people fogging buildings and outdoor scenes with what was often described as some sort of disinfectant. As I wrote at the time, I was unaware of any antiviral sanitizing agent that was dispersed in this way.
Well, I stand corrected, up to a point. There is a literature on the use of triethylene glycol (TEG) vapors as an air sanitizer, and that is a common ingredient in commercial “fog machine” devices. A lot of the literature on this technique goes back to the 1940s and 1950s and mostly studied its antibacterial action, but as you can see from those first two links in this paragraph, it can also inactivate influenza viruses and a series of bacteriophages (which were used as models for other pathogens). I can find no references specific to coronaviruses, but one could imagine that their lipid-envelope nature would make certainly make them vulnerable as well.
I hope that’s correct, though, because as you can see from that second link, there was at least one bacteriophage whose infectiousness increased after the vapor treatment. Unnervingly, that was the phi6 bacteriophage, which has a lipid envelope as well (a relatively rare trait in phages), so that makes a person wonder what the effect is on the coronaviruses as a whole. That same paper also found that TEG was overall less effective than hydrogen peroxide mist, eugenol (from oil of cloves) vapors or Pledge-brand disinfectant spray (which contains benzylammonium chlorides found in many other such products). So this whole thing is not as straightforward as it seems.
To emphasize that, here’s the EPA’s page on glycol air sanitizer products. This part in particular struck me:
Adequate experimental data is available to show that air sanitizers do not sterilize, disinfect, act as a germicide, or protect experimental animals from infections by airborne bacteria or viruses. Thus, claims of value in preventing or treating diseases, or providing any other health protection, whether expressed or implied, are not acceptable.
So I’m back to wondering if these fogging devices are doing any good, especially when deployed in the open air. There’s more rationale to them than I had thought, but is there any evidence that they’re actually doing anything? Or not perhaps even making things worse?