I’m late to the party on this but that is an interesting question worth answering.

In the 2019 ASHRAE Handbook-HVAC Applications, Chapter 62 Ultraviolet Air and Surface Treatment it states the following:

“The dose is generally interpreted as that occurring on a single pass through the
device or system. Although the effect of repeated UV exposure on
microorganisms entrained in recirculated air may be cumulative, this effect has not been quantified, and it is conservative to neglect it.”

With that said, maybe there is new research on this topic. In all likelihood though, multipass efficiency is probably hard to model in the real world with so many factors at play.

I do have a major concern, I had one installed in may HVAC system about 2 years ago my entire family myself 42 my wife 37, my son 15 and daughter 7 have all been being diagnosed with multiple neuorlogical conditions any possible connections? Thanks Jeremy

As a homeowner with a White-Rogers electronic air cleaner installed in 1989 should it be shutoff and the two washable cells replaced with a 16 x 25 Merv13 filter? I wonder if the Merv13 will reduce the airflow too much. Does the White-Rogers generate excessive ozone if it’s properly maintained?

Thanks for your input.

Sharon, see the EPA’s page on

Sharon, see the EPA’s page on ozone:

https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners

Not only is ozone bad for health, but the evidence for its effectiveness at cleaning the air isn’t very strong.  I would never have anything in my house that generates ozone.

I bought a UV light stand hat
I bought a UV light stand hat also emits ozone. I usually set it up in a room in my home fir an hour and leave the house for two hours. Then open doors when I get home to air it out. Is this dangerous for me? How much ozone can I breathe without harm to my lungs?

Anyway, thank you for taking the time to write this blog and attempting to promote the best information available at the time.