Hacker News Reader

Comment by lxgr | Hacker News Reader

Reminds me about this recent Reddit thread where somebody ran an Ozone generator in a house for hours to get rid of smells, and in exchange ended up with a much worse situation: https://www.reddit.com/r/chemistry/comments/q949go/holy_shit...

VOCs getting absorbed by surfaces was the most plausible theory in the comments there as well. Interesting to see more evidence for it.

View on HN

I've ran an ozone generator in a house for multiple days, but I went into it with the expectation that it would be uninhabitable for a period of time afterward.

Ozone won't stick around for very long. It is extremely reactive. With windows / doors open and vent fans running it will be cleared out in maybe a few hours max. The first few minutes is definitely overpowering though. You need to have a plan to turn the machine off and ventilate the building that doesn't involve walking through it for longer than you can hold your breath.

I just wore a half face respirator with an activated carbon filter (3M 7503 + 6001 + something over that for particulates, probably 2297). Quality respirators seem like simple table stakes for doing a lot of things these days. It was an off label use of the organic vapor cartridge but it worked fine (it also worked fine for cleaning with ammonia in deep cabinets). I also probably plugged the O3 generator into an extension cord which I could unplug without going in the room, the mask was just to go in and open the windows some time afterwards. It seems like, as with anything, the important part is to know the technicals of what something does and create an overall plan.

I’ve used respirators through prior lab work and be warned the ammonia grade and organic solvent grades are distinct filter packing.

Sorry, that's what I meant to imply about off label use. I should have stated it explicitly.

Household cleaning one would otherwise moderate their exposure "by smell", so I'm comfortable trusting my sense of smell through an activated charcoal filter even though it's not a listed use, is past expiration, etc.

For things (eg painting with isocyanates), I follow the directions religiously.

> It is extremely reactive.

It's two oxygen atoms with 1.5 covalent bonds each and another one in the middle with three!

If atmospheric oxygen is ‘burning’, it’s ‘nuclear hellfire’.

What surprises me about the linked reddit thread is that a chemist was surprised that pumping a bunch of a highly reactive oxygen species into a pile of random chemicals would…. produce a bunch of highly reactive random chemicals in return?

Ozone doesn’t make the soup of random elements disappear, it just oxidizes/reacts with them! Which eliminates odors if they’re trace volatiles (like most odors), but breaks a lot of other things down into even crazier chemicals - and if trapped in an enclosed space, can be bad.

Also, here is a cool video from a guy making liquid ozone [https://youtu.be/9EVrIcaVrqM?si=SyXBieoolcMntcaW]

Holding your breath won‘t save you, it damages the eyes as well.

Coincidentally, Technology Connextras (the low-effort side channel for Technology Connections) posted a video this week on ozone generators. He swears by them.

https://www.youtube.com/watch?v=RYKpKMFIdGQ

I had the idea to use an ozone generator in my car once but backed off due to a concern about it degrading interior rubbers and plastics. I guess that's not much of a real concern in practice though.

If you don't overdo it (like the guy in the reddit post did), it works great. 5 to 10 minutes with the car fan recirculating the air, repeat once or twice if needed. Just make sure you don't breathe the ozone.

5-10 minutes might get a bad fart out, but any real amount of cigarette smoking is going to take a few hours of cooking.

The lesson from the thread is to start small and work your way up, instead of just nuking it.

In the aforementioned youtube video, he mentions that his ozone generator automatically cycles, running for a few minutes every hour. That's probably how he was able to leave it running for several days with no issues, at least compared to the guy in the reddit thread.

I have been dealing with a moldy furnace caused by AC condensate overflow. I bought a small ozone generator. It had a timer for up to two hours or an indefinite on button. I was leaving for the weekend and wanted it to run for a while. I had planned to run it for the entire two days I'd be gone. I bought 3M organic vapor filters so I could go back into the house and crack open windows when I returned just in case. I would have taken the panel off the furnace and just run the generator inside the enclosed utility room. I continued to do some more reading and found that I likely would have destroyed all of the insulation on the wiring inside the furnace along with anything else plastic in that room and likely nearby rooms. Instead, I just ran it for the max two hours immediately after I left the house. Everything was fine when I got back but the furnace still smelled a bit.

It's a mild concern, but if you need enough ozone to cause meaningful damage then the smoke has probably ruined the car anyway. The key is to run it just barely long enough.

In my case the smell came from running over a rotten deer carcass. I settled on about a dozen trips through an undercarriage carwash them leaving the windows all open for a month. I figured the smell would go away eventually so I wasn't eager to risk long term damage from ozone, but my god was the smell awful for the first week.

I’ve used Simple Green to remove nicotine before. In a house you can also paint over it with shellac primer.

I chuckled at his indignance over how these things are legal and how easily you can buy them. Chinese will sell you anything to make a buck. It's just business. You can go on Amazon right now and buy a high power 1kW FM transmitter, drop shipped, and set up a flamethrower pirate radio station on a rooftop of your choosing. The cherry on top is they are likely super low quality with crazy spurious emissions.

Of course the FCC will probably be up your ass in half an hour if you tried it; the point is the equipment is readily available in a few clicks, no questions asked.

Don't get me started on the instantly-blind-yourself-and-everyone-else lasers you can buy on eBay (they'll sell you matching counterfeit laser goggles too).

It would be "the Chinese will sell you anything" if they bought it on Alibaba and imported it on their own.

If you buy it on Amazon, it's "the Americans will sell you anything". If Amazon is too lazy to do due diligence on their third-party sellers, the blame should fall on Amazon if the item turns out to be illegal or dangerous.

Amazon chose to make direct fulfilment almost indistinguishable from third-party fulfilment. Don't want to be treated like a regular store? Then don't make your marketplace behave exactly like a regular store for the buyer!

Nothing to do with china. Americans will sell these things

I mean numerous US companies sell caffeine powder on Amazon as a supplement for gym and tech bros. A teaspoon of it will kill a grown man.

How do they find you and how would they know to look for you?

Triangulation by signal strength. Only takes 3 measurements, less if you have a small number of properties. If you're injecting intermittently it gets harder but they'd pinpoint you from other signals in the end with LEA assistance to get the cellphone data. (You did remember to turn it off, right? But how are you getting the sms requests in for play lists?)

Is it even worth it to pirate on FM these days? People don't really scan the band looking for new stations, I know the aim is often to provide for an underserved audience but anyone can set up a web stream for this purpose now and avoid the complexity of having to work in a clandestine way.

I like listening to pirate radio but it's mostly shortwave and mediumwave via an SDR, more or less anoraks broadcasting to other anoraks. I know FM pirates are still operating in London but I've never heard any in my current city.

Sorry to break it to you, but your "recent" thread is 4 years old.

I have a cheap ozone generator I've used for cleaning cars and boxes of used books. Used at the right concentrations and durations, it's magical! Run it outside or in a sealed tote.

But yeah, they'll sell them to just anyone. Electricity and air go in, and ozone (a reactive, toxic chemical) comes out for as long as you leave it plugged in.

Books?

In a smoker's household, everything reeks of the smell for years. And the porous nature of paper causes it to retain the smell too.

What's worse is that something, I assume tar, actually seeps in everything. I was looking at a house on a particularly hot day once, and the bedroom walls were 'bleeding' some weird black substance.

I informed the owner, who exasperatingly told me he's been scrubbing them down for weeks but it won't stop. Every time it got hot outside the walls would start again. Apparently his parents smoked heavily in that bedroom for decades.

The correct thing to do is to strip the walls and start over. Since no one actually wants to do that, smoke-covering paints are a thing you can buy.

Yeah, they're like a Kindle, but instead of one screen that changes they have hundreds that remain static.

DRM-free, too, and made from an eco-friendly carbohydrate foam!

Lol - excellent!

Storage capacity remains an issue, though.

Is it really DRM-free if making copies is really hard process and you even need to crack part of it(spine). Or even worse remove part(the binding)...

At least it isn't a criminal offense to publish instructions on how to do it.

And you can resell it or lend it out to a friend.

The proper way to get rid of smells from a smoker is to wash all of the paintable surfaces with trisodium phosphate, paint all of the walls and ceilings with Kilz primer, and then clean the floors, doors, and woodwork (and everything, windows, etc) with a solvent that removes the tar and resin (or paint them with Kilz too). If there is carpet, remove the carpet and pad and install new carpet. Might need to replace fixtures and furnishings depending on how bad it is.

So yeah, smoking in a house is insanely destructive and takes a long time to actually remove the odor forever.

Also, check all of the drains (including floor drains) to ensure there is water in the trap.

It was quite interesting in the UK when the smoking ban kicked in for public places, and how many pubs needed this sort of treatment once people stopped actively smoking in the premises, as without the active smoke to mask it people noticed that the place was actually a bit nasty.

For inhabited spaces there are ionizers available optimized to produce negligible amounts of ozone. They produce O2- and N2- ions instead, which are much safer, even beneficial. They help not only with VOCs but dust too unlike ozone which is a neutral molecule.

The confusion with ozone generators is understandable but very unfortunate here.

"I can't find any information on how to get rid of lingering ozone"

I'd feel embarrassed if I was their alma mater reading that.

That thread is illuminating. I see two serious problems.

- - -

First, the quality of a modern American education.

Let's assume 2000sqft house with 8.5ft ceilings = 17k cu ft or ~500 m3, 1-0.1 μmol/mol ozone produces irritation to respiratory passages, so we need 1-0.1g total ozone left in 500m3 of house.

"170g of a highly reactive gas is generated over two days in a house full of organic materials. The windows are open and the heat is on; after what time will less than 0.1g gas remain?"

Make virtually _any_ assumptions and the answer could not possibly be longer than "minutes."

Mind you, I used very generous numbers and assumptions here. Mexico City averages over 0.1 μmol/mol and seconds of Mexico City air does not "totally destroy" anyone's lungs or cause you to cough up green phlegm.

In other words, with a few seconds of basic math and two basic facts about ozone it is trivial to see that the ozone is effectively gone. This guy has a university biochem degree and experience with organic synthesis? He's on there calling for an "atmospheric chemist" and thinking up ideas to fill the entire house with aerosolized cooking oil (!?!?!?) What is it that makes so many people today entirely incapable of critical thinking? Mind you, this guy literally once had a professor give him a hands-on demonstration of the rapid reaction of ozone - the sort of hint you would give if a student somehow failed the above question - and he still somehow couldn't get it after a week of Googling and reading "the literature."

How do we teach critical thinking?

- - -

Second, the modern synthetic chemicals we live with.

Ozone is always present around us, sometimes at quite high concentrations, depending on your environment. Obviously (... perhaps not always too obviously ...) it is always reacting around us. Most people own hundreds to thousands of pounds of modern synthetic materials. Innovative new chemistries. Formulas changed yearly. Those things are not static, they are off-gassing, they are reacting, they are releasing compounds unknown into the air we breathe. Just your mattress alone might have a hundred pounds of polyurethane foam, the precise composition of which is unknown to any one individual. Perhaps it is enclosed in a polyester cover, and then likely one treated with a fire retardant. Perhaps the corner protectors are recycled plastic of unknown origin, and then maybe they contain an odor-reducing additive. How do all these things react with the air around us? How do they interact with each other? I suspect that when we eventually study this better we are not going to like what we find - but for now, why do we allow plastics manufacturers to use us all as guinea pigs?

Reply on news.ycombinator.com