I’m stunned that the word “duct” doesn’t appear in this article. UV in ductwork is cheap, very effective, and has no downsides. I’m flummoxed why it isn’t widely employed. Can you help? Thanks.
Had something of a similar reaction but the note about far-UV not having the same problems as other UV serilization (i.e., also harmful to humans) I gather the point is about locality. UV in ducks will kill viri in the air system. But the spread of an airborn illness goes host-to-target before it passed through the air system.
As such seems that while the in-duct UV solution would help limit spread, it’s not going to do much to clean the air in the room while people are in it exhailing, coughing or sneezing, talking.…
I suspect it does little to protect the people directly next/in front of a contagious person but probably good for those practicing that old 6 foot rule (or whatever the arbitray distancing rule was).
The word duct doesn’t appear here because far-UV installation is most useful (compared with other wavebands) for whole-room application—agree that UV in ductwork has the potential to be very useful, but you’d use a longer wavelength if people weren’t going to be directly exposed, because you can crank up the power on longer UVC wavelengths without producing tons of ozone. (Far-UV is specifically 200-230 nm, but UVC goes up to 280 nm.) I focus on far-UV because the excitement about far-UV specifically has to do with whether there’s potential for it to be installed in such a way that it can stop in-room pathogen transmission before air entirely circulates or recirculates, which could be a big deal for pandemic prevention.
Why in-duct UVC isn’t more widely employed: I don’t know a ton about its current adoption level but retrofitting ductwork is a hassle, even just in the simple sense of needing to contract technicians to do it. Anyway, its efficacy isn’t guaranteed; you need to know the power of the light you’re getting, which many consumers are not equipped to assess. The efficacy is a combination of the light’s power and the speed of airflow through the duct, UV lights are often sold at an insufficient power to effectively disinfect air, and consumers can’t necessarily evaluate whether it was a good investment (common problem across air cleaners in general).
My guess is that we’re still on the leading edge of ordinary consumers thinking of air quality as something that they can and would want to control for anything beyond comfort, particularly for pathogen (or allergen, or mold) removal. All air quality tech faces that problem (and my blog post was trying to address the problems far-UV faces beyond that). Anecdote I found interesting: Some colleagues attended a global indoor air quality conference earlier this year and reported that something like 80% of the sessions were about comfort in the indoor environment, while about 5% were about pathogen control.
I’d be interested to know what the numbers on UV in ductwork look like over the past 5 years. When I had to get a new A/C system installed in 2020, they asked whether I wanted a UVC light installed in the air handler. I had, before then, been using a 70w UVC corn light I bought on Amazon to sterilize the exterior of groceries (back when we thought fomites might be a major transmission vector), and in improvised ductwork with fans and cardboard boxes taped together. Getting a proper bulb—an optimal wavelength source—seemed like a big upgrade. Hard to come up with quantitative efficacy numbers, but we did have a friend over for the day, who turned out to have been in the early stages of covid, without getting infected. Our first infection was years later, at a music event.
I’m stunned that the word “duct” doesn’t appear in this article. UV in ductwork is cheap, very effective, and has no downsides. I’m flummoxed why it isn’t widely employed. Can you help? Thanks.
Had something of a similar reaction but the note about far-UV not having the same problems as other UV serilization (i.e., also harmful to humans) I gather the point is about locality. UV in ducks will kill viri in the air system. But the spread of an airborn illness goes host-to-target before it passed through the air system.
As such seems that while the in-duct UV solution would help limit spread, it’s not going to do much to clean the air in the room while people are in it exhailing, coughing or sneezing, talking.…
I suspect it does little to protect the people directly next/in front of a contagious person but probably good for those practicing that old 6 foot rule (or whatever the arbitray distancing rule was).
Just my guess though.
The word duct doesn’t appear here because far-UV installation is most useful (compared with other wavebands) for whole-room application—agree that UV in ductwork has the potential to be very useful, but you’d use a longer wavelength if people weren’t going to be directly exposed, because you can crank up the power on longer UVC wavelengths without producing tons of ozone. (Far-UV is specifically 200-230 nm, but UVC goes up to 280 nm.) I focus on far-UV because the excitement about far-UV specifically has to do with whether there’s potential for it to be installed in such a way that it can stop in-room pathogen transmission before air entirely circulates or recirculates, which could be a big deal for pandemic prevention.
Why in-duct UVC isn’t more widely employed: I don’t know a ton about its current adoption level but retrofitting ductwork is a hassle, even just in the simple sense of needing to contract technicians to do it. Anyway, its efficacy isn’t guaranteed; you need to know the power of the light you’re getting, which many consumers are not equipped to assess. The efficacy is a combination of the light’s power and the speed of airflow through the duct, UV lights are often sold at an insufficient power to effectively disinfect air, and consumers can’t necessarily evaluate whether it was a good investment (common problem across air cleaners in general).
My guess is that we’re still on the leading edge of ordinary consumers thinking of air quality as something that they can and would want to control for anything beyond comfort, particularly for pathogen (or allergen, or mold) removal. All air quality tech faces that problem (and my blog post was trying to address the problems far-UV faces beyond that). Anecdote I found interesting: Some colleagues attended a global indoor air quality conference earlier this year and reported that something like 80% of the sessions were about comfort in the indoor environment, while about 5% were about pathogen control.
I’d be interested to know what the numbers on UV in ductwork look like over the past 5 years. When I had to get a new A/C system installed in 2020, they asked whether I wanted a UVC light installed in the air handler. I had, before then, been using a 70w UVC corn light I bought on Amazon to sterilize the exterior of groceries (back when we thought fomites might be a major transmission vector), and in improvised ductwork with fans and cardboard boxes taped together.
Getting a proper bulb—an optimal wavelength source—seemed like a big upgrade. Hard to come up with quantitative efficacy numbers, but we did have a friend over for the day, who turned out to have been in the early stages of covid, without getting infected. Our first infection was years later, at a music event.