[Bender]

My UV sterilizing lights make my room smell like O3 Ozone and that smells nothing like spent gun-powder to me. The only other time I have smelled the same thing is when there has been mass lightening events in the sky. Were they talking about actual black powder or nitrocellulose? I've smelled black powder at the range when people bring out their antique rifles and that also does not smell like Ozone to me.

[mr_toad]

‘Ozone’ is the smell of ionisation, ‘gunpowder’ the smell of oxidisation.

[IAmBroom]

Half right. Gunpowder is mostly the smell of sulfur compounds.

[coffeebeqn]

Photocopiers smell like ozone when they run if anyone’s forgotten the smell

[saltcured]

I also associate ozone with some electric motors, I think because they have brushes that arc during operation. Older power tools I encountered in the 1980s often did this, and you could see the blue arc if you looked into the vents at the right angle.

[aduty]

Brushless motors are popular now, but if you get the cheaper cordless tools they'll still have brushed motors. I have some Black & Decker 20V ones that do it. They tend to have less torque but I don't need Milwaukee or Makita tools just for diy around the house.

[Bender]

Photocopiers smell like ozone when they run if anyone’s forgotten the smell

Those are similar but sweeter. If I sterilize a room with UV it has a very distinct smell like nothing else aside from lightening and stun guns. I would UV the bathroom right now but then I have to vent the entire house and its 34F outside right now.

[echelon]

I don't think any of you should want to be smelling Ozone.

Diatomic oxygen is already a highly reactive fuel that is killing us and giving us cancer every single day. The ozone species is even more oxidative.

Oxygen is how we move about the energy gradient, but it's also killing us. Ozone is worse.

"Air purifiers" with ionization are probably not worth the squeeze.

[KennyBlanken]

The permissible exposure limit for ozone is 0.1 PPM.

The IDLH (Immediately Dangerous to Life and Health) level for ozone is five ppm.

That's half of chlorine which is 10 ppm.

Most major brand air purifiers put out a very minimal amount; the ionization is beneficial because it makes the really tiny (and thus most hazardous) particles clump and fall/stick to surfaces faster.

It's the offbrand units that generate lots of ozone to make people think they're "doing something", and commercial ozone generators for car/room deodorizing, that you have to be extremely careful with. Those need to be set up and then the room left for hours for the ozone to react with stuff, and then ventilated thoroughly.

[vintermann]

I don't trust most air purifier manufacturers. They totally would add a fancy-sounding feature which sounds good, even if it has negligible effect, or even negative effect. Case in point: they're still pushing ultrasonic humidifiers.

The tiniest particles aren't necessarily the most dangerous, so even if "clumping" worked as advertised, it wouldn't necessarily be good. Air filters are worst at filtering particles at about 0.3 microns, they're better at filtering smaller ones (I understand it has something to do with brownian motion). I wouldn't be at all surprised if a similar thing affected our biological "filters". Either way, if you have a filter, you don't need UV to clean air. Just push more air through it if you need cleaner air faster.

[dmurray]

Aside from "killing us and giving us cancer every single day", isn't "diatomic oxygen" the stuff we breathe every single minute and need to survive?

I'm not normally one to miss the sarcastic or satirical posts, but this one seems oddly earnest.

[JumpCrisscross]

> isn't "diatomic oxygen" the stuff we breathe every single minute and need to survive?

I think they're referring to oxidative stress [1] caused by cellular respiration.

[1] https://en.wikipedia.org/wiki/Oxidative_stress

[Brian_K_White]

Yes and it wasn't sarcastic, both things (what you said and what they said) are simply true. I think their point was not to be alarmist like you should stop breathing, but simply that everyone knows the one thing and most people don't know the other thing, and it gives scale or context to the "you don't want extra ozone".

[heavyset_go]

Part of aging is the result of oxidation of DNA over time and as cells reproduce.

[echelon]

The other posters here are right. I just wanted to point out the odd beauty in the fact that the fuel that makes our biology possible is also one of the things that is killing us. If you get a chance, read up a little bit on redox reactions and oxidative stress and take a moment to appreciate that.

We harness the energy of oxygen. It's the fuel that powers us. But it's also so reactive that it's constantly damaging our DNA and intracellular components. Over time it ages us, causes cancer (daily - our biology fights back!), and will ultimately be part of what wears us down and kills us.

Look at oxygen as a very reactive and energy abundant fuel. And then consider its abundance in our atmosphere. And then how it powers human locomotion, human biochemistry. And how it creates free radicals and chain reactions that strip our DNA and mutate base pairs. And all the tens of thousands - no, countless more - interactions and reactions it's having all throughout our bodies at all times. And how our biology evolved compensation measures to keep those deleterious effects at bay for as long as possible - as long as necessary - to enable reproduction.

Our biology is utterly awe-inspiring when you think about it. An incredible machine molded by our gravity well and abundantly available energy. Not just fighting against entropy, but actively sailing its turbulent energy gradients.

[Bender]

Absolutely. I vent the house after running UV lamps using a 4400 CFM air mover. I leave the house and run errands. I have 3 of these [1]

They have a remote control that "arms" them and it starts beeping slow, the faster, then much faster then activates. It kills insects be destroying their lungs and entirely destroys mold, bacteria and even damages viral material. Hospitals run the same lamps in wings that they close down for sanitation. The entire area has to be 100% vented.

[1] - https://www.amazon.com/AeraLight-Whole-Surface-UV-Sanitizer/...

[alfiedotwtf]

I worked for a germaphobe, and he put one of these ozone-injecting air purifiers in our tiny office. Every morning I would walk in and it felt like I was walking into a thunderstorm from the smell. No gunpowder, just thick ozone

[cyberax]

In general, if you can smell ozone, you should NOT be in that place.

[heavyset_go]

How does this affect surfaces like walls, finished wood furniture and floors, plastic, paint, etc?

I imagine it will cause some material to off-gas aldehydes at the very least.

[vintermann]

I don't think off-gassing is a problem, ozone treatment is famously how they get rid of cigarette smell in used cars, furniture and whole apartments.

But I would worry about the effect on e.g. plastic seals. There are a lot of plastics that become brittle with ozone exposure, let alone UV exposure.

[mjanx123]

How long would it take for the ozone to recombine back, if you didn't vent the house?

[rrr_oh_man]

Side quest: Can you tell more about the UV sterilisation thing? Why do you do that? How often? Where? It seems like such a specific thing to do.

[genewitch]

Hi, i am not who you asked, but i feel like i've done enough research and have some warnings. UV-C light itself is antimicrobial, but only for surfaces that the light touches, and in the case of cloth it needs to penetrate a bit.

There are at least two types of UV-C light bulbs, as well as literal ozone generators that use ceramic platen and a fan. The type of UV-C bulb that is most common on Amazon and Ali is ~254 nanometers, and _does not_ produce Ozone. It does leave a smell, but it's more like an oldschool hospital antiseptic smell. probably the smell of the dead germs, yay.

Now 185nm is actually the correct size to turn O2 around the bulb into O3 (and more oxygens too, i once read, i think, kinda like cracking hydrocarbons to make longer chains or something).

UV-C bulbs (not base, which is an edison base) that can sterilize a room in 5-15 minutes are about 15-20 CM tall, with four crystal tubes that are connected together standing up on the base. image here [0]

you must run a fan over them if you want your money's worth. they get hot, the bases get hot, it makes the most sense in non-carpeted rooms to aim the crystal down and the base up, so that is real rough on them. that took me 2 bulbs to figure out.

If you can find a reputable place to get the box with ceramic and a fan that lasts more than 5 minutes, let me know, because that's closer to what i want for bedrooms and stuff.

The UV-C 185nm bulbs work great to make a car stop stinking, too! completely removes cigarette smells, if the car hasn't been smoked in for a while. run the A/C full blast and run the bulb for 15 minutes, open the windows for 5 minutes, roll em, sniff. Still smell? another 10 minutes, in the back seat, full A/C blasting. vent, sniff. Faint smell? replace the cabin air filter. Charge customer(?)

and i'm going to respond to your followup question to the GP as well: Covid. Obviously. They were telling us it would live on groceries and deliveries and that, so i put all deliveries in my laundry room and dosed em with UV-C for a minute. CDC or whatever studies said that 10-60 seconds was more than enough to kill sars-ncov-2.

I only use it for freshening cars, rooms, bathrooms, etc now.

WARNING: Do not be in the room with any UV-C light for more than a few seconds. Do not look at the bulb for literally any more than necessary to ensure it is on and safe. they make safety goggles that wrap your entire eye sockets to protect from UV, too. if you get a 185nm bulb, either completely ventilate the room with fresh air, or leave it sealed for 60 minutes then open it up for a few minutes, all the ozone reacts and goes away or something.

UV-C hurts your skin, yes, but it will make your eyeballs literally itch. so don't, don't don't look at it. they are not blacklights.

[0] https://m.media-amazon.com/images/I/71LgjON7J+L._AC_.jpg

[dreamcompiler]

> WARNING: Do not be in the room with any UV-C light for more than a few seconds.

This advice does not necessarily apply to far UVC (200-235 nm), which appears to be much safer for human skin and corneas than UVC outside this specific band. More research is needed before calling it "safe" but far UVC is almost certainly less hazardous than the rest of the UVC band.

Pay close attention to wavelength when purchasing UVC light sources.

https://en.wikipedia.org/wiki/Far-UVC

[genewitch]

254 doesn't make ozone but; yes, i explained the two i have used and researched. i have not researched far-UVC. it's still germicidal, i still wouldn't want to be in the room with it. I had to check what wavelength "common" UV lasers are, and i'm guessing 261nm or so. If you aim that at your skin, it feels hot real quick. Kinda feels, to me, like my entire life i've been told that all UV is bad, but UV-A blockers are snake oil, etc.

I'll keep my eye out for more research on far-uvc and the possibility of getting a bulb to test.

oh by the way, i must have sent back 2 dozen "185nm" UVC bulbs from a dozen "manufacturers" because they didn't produce ozone, because they were fraudulent listings of 253.7nm bulbs - so this is why i was trying to steer people away from amazon and ali, as it's real easy to get the wrong type if you're looking for ozone. I've only managed to acquire 4 bulbs total in the last 5 years that produced ozone, and i burnt out two before someone said "put a fan on it, those bulbs are designed to be inside an air exchanger!"

[vintermann]

Yes, this is a common dilemma in air sterilization. Far UV-C isn't as nasty for skin, but it produces ozone, and ozone is nasty and really bad for your respiratory health.

[bertylicious]

What about shadows? The UV-C light can't reach everywhere, right? What about the back and undersides of product packaging you want to sterilise?

[genewitch]

i didn't touch the bottoms and the backs. like, put on socks, grasp box between socked feet, open box, remove the air bag packaging stuff, and if you want, UV it again. however, if you're using 185nm the ozone will get the "back" and inside. not the bottom, maybe, but if you're concerned, flip it over. If you're concerned, make sure you read research papers on exposure time of pathogens to UV-C and/or Ozone to population destruction. as i mentioned, the papers i read before i bought the bulbs said 10-60 seconds for covid. originally there was a recommendation for up to 3 minutes, but some research group went and tested shorter and shorter lengths of time. so you'd need to know the pathogen you're targeting and run it accordingly.

[Bender]

I primarily use them in the bathroom to kill off mold and bacteria about once every 3 months. I open up the water heater closet, drawers, etc... then I fire one of them up. I've used them in other places but the more they are used the more I have to vent the house.

[rrr_oh_man]

Has anything prompted you to do this? Have you been doing this for a long time? Have you noticed any changes (yes, I assume?!). Sorry for pelting you with questions, but this is so... interesting and I'm tempted to give it a shot.

[Bender]

Two of you are curious [1]

[1] - https://news.ycombinator.com/item?id=47812225

[LoganDark]

Brushed DC motors (as in some drills, toothbrushes, etc.) emit ozone. Some light switches also create ozone-producing electrical arcing if you hold them perfectly between the on and off positions, or slowly cross the midpoint. (Less easy with the newer-style, less accessible rocker switches.)

[colechristensen]

You might be smelling the oxidation of biologicals via ozone and UV might have the same chemical effect

[KennyBlanken]

The only thing you're doing by sterilizing your house like that is making your immune system weaker.

Humans are built to withstand a constant assault on their immune systems. We couldn't have survived if we didn't.

[Bender]

Don't worry I know what I am doing.

[VoidWarranty]

Careful. The venn diagram bubble depicting your statement overlaps heavily with the anti-vaccine bubble.

Its a bit naieve to claim that cleaning one's home will result in an extinction of enough microbes so as to be threatening to our immune system.

[mjmas]

See: Polio

https://en.wikipedia.org/wiki/History_of_polio

> [...] Better hygiene meant that infants and young children had fewer opportunities to encounter and develop immunity to polio. Exposure to poliovirus was therefore delayed until late childhood or adult life, when it was more likely to take the paralytic form.[22]

[Bender]

Nothing strengthens an immune system like a weekly furry party or attending "tough mudders" events.

[manwe150]

That’s because the parent claim is known as the hygiene hypothesis and has been disproven by science, in common with anti vaccine claims. The immune system has not been shown to benefit from training, but has been shown to be damaged by illness.

[imtringued]

I'm not sure how you would disprove the hygiene hypothesis, because it is a really weak claim and rejecting weak claims is really difficult.

The anti vaccine position makes a very strong claim, namely that vaccines will cause complications that are strong enough to justify not vaccinating children, which is obviously false since a lot of the diseases that are vaccinated against have actually killed children and the vaccines have dropped child mortality significantly and the complications that are supposed to be avoided by refraining from vaccines tend to be both rare and non life threatening.

You can't make the same argument with the hygiene hypothesis, because the claim is really weak. Nobody is saying that extreme hygiene will kill you. The argument is along the lines of "lack of exposure to environmental microbes, viruses or allergens may lead to an unprepared immune system that hasn't developed a wide variety of anti bodies or is more likely to develop allergies or autoimmune problems".

I'm not sure how I would be able to argue against this claim since it only takes one microbe, virus or allergen to make it true.

The context here isn't hand washing vs not hand washing, it's aggressive ozone + UV sterilisation vs regular hygiene.

Not to mention that the hygiene hypothesis has an even weaker version still, namely the "old friends hypothesis". It seems pretty weird to equivocate this to being against vaccines.

[vixen99]

Maybe you should qualify 'anti-vaccine claims'. Throughout the history of vaccines which have saved countless lives, some people have died or suffered severe reactions linked to a vaccine. This is hardly surprising given our metabolic heterogeneity.

'Anti-vaccine claims' suggests a taking of sides on that knee-jerk division into those who claim without evidence that almost or even all vaccines are deadly and on the other hand, those who are frankly contemptuous of any claim that a particular vaccine (evident particularly with the vaccines developed in response to the Covid outbreak) might be dangerous for certain people. Both extreme views have been on view recently and are indefensible.

The major issue here is the difficult task of identifying people likely to react badly to any specific vaccine.

Meanwhile 'Congress and Institute of Medicine Confirm Government Licensed and Recommended Vaccines Can Cause Injury and Death' and 'The 1986 National Childhood Vaccine Act was the first U.S. law to officially acknowledge that childhood vaccines licensed and recommended by the federal government, which are routinely mandated for school attendance by state governments, can and do injure and kill a minority of children.'

[corysama]

The ozone report was specifically about space walks. The gunpowder report was about moon walks.

Presumably, moonwalks would also have some ozone like the space walk did. But, maybe the burning-moon-dust gunpowder smell was a lot stronger than the vacuumed-metal/paint ozone smell.

[adrian_b]

I assume that they talk about black powder.

The dust that comes from meteorites contains up to 4 fractions: silicates, which cannot be oxidized, metallic iron, which oxidizes, but it does not form volatile substances that can be smelled, hydrocarbons in the form of a tar or pitch, which can burn but it cannot be ignited easily, and finally a fraction made of iron sulfide (troilite) with small quantities of other sulfides.

In contact with air, the sulfides will be oxidized, releasing sulfur dioxide. Burning black powder also releases sulfur dioxide, which is the main reason for its smell. Burning pure sulfur will produce the same smell.

[lifeisstillgood]

Sorry for the tangent, but you sterilise a whole room with UV light? Is that efficient ? Do you do it after tidying / cleaning ? Is there a medical reason for the extra part? Is it just cool :-)

[Bender]

The house came with a bacteria that would normally be hard to get rid of. UV, bleach and peroxide took care of it. I just repeat the process to ensure there is no bacteria or mold. This seems to bother people in this thread which I find fascinating. A part of me wants to bring my black light to their dwelling.

[vl]

I have mold problem in one of the bathrooms. What would be your recommendation? Seal off bathroom and run UV, then vent? Or do I need to do entire house? I can also seal off bathroom and bedroom. Thanks!

[blub]

No, UV is unrelated to your issue.

First you need to figure out if it’s a surface infestation because of condensation or if it’s a constructive thermal bridge. The latter can be solved by raising the surface (wall, ceiling, etc) temperature through insulation or more inefficiently special heaters designed for this purpose.

In both cases, the contaminated material is removed down to the plaster or masonry. Wood, wallpaper and similar materials will likely be deeply contaminated and must be removed. For areas larger than 1 sq meter, it’s better to get a specialized contractor which will use HEPA vacuum cleaners, special bags, etc to ensure that the mould spores don’t spread in other rooms.

For small areas the agents of choice are bleach or hydrogen peroxide, both available in products for home use.

[blub]

Was it from flooding or how did it get there? How did you detect it?