[miduil]

I share their sentiment, especially because they are trying to explain the topic for the novice buyer - but I think it oversimplifies the issue and the discussion/benefit of UVGI.

UVGI does not create Ozone, some companies even sell certified lamps that will definitively not go into the UV spectrum that can cause Ozone.

This is true for UV-C and in the postings mention of new far-UVC LEDs.

https://www.uvresources.com/the-ultraviolet-germicidal-irrad...

For personal homes UVGI is most likely not needed, unless immunocompromised I'd guess. For hospitals, pharmacies, schools, airplanes and other high risk institutions I would guess that this could prevent plenty of deaths.

Edit: Their criticism is about the high-voltage needed for Mercury-vapor UV-C lamps. This can leak ozone, also if the glass is not filtering the 185nm wavelength properly that will contribute even further. The article talks about LEDs which will definitively not leak into this range. Also as far as I know the specific wavelength of pressure-lamps is not input-frequency defined as implied by the interviewed guy - not exactly sure what he's referring to. My takeout would be only buy mercury-pressure lamps from trusted sources with proper certifications in place.

[throw0101a]

> I share their sentiment, especially because they are trying to explain the topic for the novice buyer - but I think it oversimplifies the issue and the discussion/benefit of UVGI.

Most people probably don't change their air filters often enough at home: I have zero confidence of them maintaining an UVGI (themselves, or wanting to shell out the cash for someone to come in).

The best thing to do is circulate air per ASHRAE-recommendations and get high-MERV filters (and hope they are swapped regularly).

[scythe]

I work in medical physics. The issue of ozone generation from ionizing radiation has come up from time to time. In radio/fluoro rooms, it's basically undetectable. In radiotherapy, it might reach the odor threshold after long treatments, but this is rare.

These are systems that produce radiation way beyond the energies that can create ozone via UVC. The ozone level is barely measurable and not considered a serious risk. In the video you linked, the narrator opens by saying that ozone barely even makes it through the ventilation system, which is consistent with my understanding of ozone: a reactive, unstable gas. And Dr. Siegel emphasizes this as well: O3 doesn't stick around easily. He doesn't seem to share the presenter's obsession with ozone.

Frankly, I found the video tedious and gave up after a minute. Also, the Siegel's background is mechanical engineering, and he's obviously hedging his statements. Here's an actual scientific review of O3 generation by lamps:

https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391

Critical quote: "Again, soft glass UV-C lamps cannot generate ozone".

>I have zero confidence of them maintaining an UVGI

An unmaintained mercury-vapor lamp will not suddenly violate the laws of physics by emitting radiation below the 254 nm spectral line of mercury. The only mechanism that would alter the ozone generation rate is electrical arcing outside the device, which is really a concern with any electrical equipment and not specific to Hg lamps.

Frankly, most of your posts on this sound like you watch too many videos and don't read enough. "Performing chemistry experiments on yourself" — really? This stuff has been studied for centuries.

A more realistic concern with UVGI is that they don't kill everything and can't replace other ventilation components. Some microbes are very, very radioresistant and you're just not going to deliver 10 kilogray in a continuous flow duct using reasonable levels of power.

[sidewndr46]

you don't have to have arcing in the device. Coronal discharge is the normal way to create ozone.

[aidenn0]

I used to have the air-filter changing forgetfulness problem; I got an online subscription to the filter my furnace takes and now I change it like clockwork.