Portable Air Purifiers with UV Lights Lack Evidence for Efficacy

As our lives of masks, six foot separations, shutdowns, and other characteristics of the COVID-19 era quickly begin to fade, I still have some lingering questions – one more nagging than the others. I realize that sometimes our leaders often have to make decisions based upon minimal information and, at other times, do some things more for show than might actually benefit society. 

My question is regarding the small air purifier units with filtration and UV lights manufactured by a number of companies. Maybe some states had different approaches than what I was seeing in the places I travelled to, but as states were opening back up, these air purifiers – about the size of a medium-sized trash can – began showing up in schools, office buildings, waiting rooms, workout gyms, bus terminals and about any other place people gathered.

In schools, for example, a unit would be placed in the front or back of a classroom. I know of school districts which have spent $1 million or more on these air purifier units. Some states have had to have spent tens of millions of dollars on these units.

When these types of units were first introduced, I tried to do my research to find independent test results on the efficacy of the units to meet the manufacturers claims – things such as how effective the UV lights were, how the units helped in a classroom environment, what maintenance was required, etc. Unfortunately, I was not able at that time to find the test results I was looking for to justify the cost being spent around the country for these units. 

One concern was with the short duration of time that the air was exposed to UV. Another was the effectiveness of a unit in a large space such as a classroom. Lastly, if the UV was effective in reducing airborne contaminants, were they still effective after 6, 8, or 10 thousand hours of operation? I know of many owners who have had these units in place for several years and when asked if they have ever changed a UV lamp, I have not gotten any acknowledgment that this was ever done (although I am sure some have done so).

If these units with UV did not do what the manufacturers claimed, were engineers party to this deception? When we were supporting owners installing, for example, these units in the front or rear of a classroom and taking the position that this was helping the indoor air environment within that classroom, did we have an understanding that the UV light was not going to perform as claimed? Were we supporting owners so that they would look like they were doing something for the space air quality when in actuality, it was just for show?

I have tried through local fellow engineers, equipment suppliers, online engineering sites, and by other means to get information on what independent testing had been done for portable space air purifiers with UV. My question was simple and straightforward- were the claims of the various manufacturers accurate that these type of units with UV lights were helpful in reducing bacteria, viruses, and microorganisms within a space? I think I know the answer to the question based the response, or the lack of responses, from my fellow engineers.

We, who were working with these entities that spent a lot of money – maybe hundreds of millions throughout the country – understood that this was more for show to make it look like we were doing something to help provide a cleaner indoor air environment while we really knew that these type units with UV were not really doing much of anything. Maybe I am wrong with this conclusion, but I have not heard otherwise from anyone – including the manufacturers.