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Build a do-it-yourself home air purifier for about $25

uofmhealth.org

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Re: Build a do-it-yourself home air purifier for about $25

#311

Earlier quoted context omitted.

Safety advice: If you decide to try this at home, please keep in mind that mixing chloride based cleaning agents with an acid will release chlorine, which is toxic enough to have been used as a WW1 weapon.

Or similarly toxic chloramine gas, when combined with cleaning agents containing ammonia, such as Mr. Clean.

Chloramine is responsible for the classic "swimming pool smell", as the chlorination in the pool reacts with urine, sweat, and other nitrogen-containing organics. Chloramine is a less effective disinfectant than free chlorine, and more irritating to swimmers, and diffuses out of the water more slowly, so this is why you shouldn't pee in the pool, and why you should rinse off in a shower for a minute before entering. Mainly, just don't pee in the pool.

If you smell "swimming pool" where no pool exists, it might be prudent to leave the area immediately and take a 1000 mg vitamin C tablet, before making any attempts to discover the source of the smell. (Taking vitamin C after the damage is already done won't help.) If the odor is especially strong, or if it causes any irritation to your nose and eyes, evacuate, and do not return. Call your emergency services number and tell them you smelled a strong chlorine odor.

Don't combine bleach cleaners with ammonia cleaners, ever. Don't even store them in the same place. Also avoid mixing bleach with acids, such as vinegar.

Re: Build a do-it-yourself home air purifier for about $25

#312
post #309

Earlier quoted context omitted.

How do you know you are measuring bad particles, and not good particles (like salts if you live nearby the sea)?

Why would you want to keep salt in the air? It will promote rusting.

The question was more about whether the measurement tool provides useful feedback in case of "salty" air. Filtering is a lot of work, and might not be necessary.

Re: Build a do-it-yourself home air purifier for about $25

#313
post #150

Earlier quoted context omitted.

I just bought the same model. What makes it so effective is that it has a filter on four large sides so it can process a large volume of air very quickly.

Does it spew out ozone? My memory may be off but I remember this model not meeting CA air purifier standards which was why Amazon couldn’t ship it to me

no, there is no ozone generator in this model (usually that's done using electrostatic plates).

Re: Build a do-it-yourself home air purifier for about $25

#315
post #309

Earlier quoted context omitted.

How do you know you are measuring bad particles, and not good particles (like salts if you live nearby the sea)?

Why would you want to keep salt in the air? It will promote rusting.

It's healthy apparently. I've been to a health resort in Ciechocinek where they have huge wooden construction through which they flow salted water so it evaporates and makes the air better for people there.

It's called "tężnia", have no idea how to translate that :) Google gives "graduation tower" but I doubt it's correct.

https://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Ci...

Re: Build a do-it-yourself home air purifier for about $25

#316

Earlier quoted context omitted.

Off topic, but hey so I just moved to Chiang Mai. Do you think it's worth even sticking around here during that time? I was thinking about just heading to Bali instead. Not sure how bad it really gets.

It's really awful, especially if you're sensitive. Some people aren't bothered by it too much, but it really affects me, so I try to get away. We have some pets, but it hasn't been too hard to find a house-sitter. (Although I always feel a bit guilty, and try to be honest about the smoke.) These articles are concerning: * https://www.theguardian.com/environment/2018/aug/27/air-poll... * https://www.scientificamerican…

Awesome thank you much for the links! It seems like a very awesome place so far. I'm loving it.

Re: Build a do-it-yourself home air purifier for about $25

#317
post #246

Earlier quoted context omitted.

Northern Scandinavia and west of Urals (I live here) have moist winters (70+% RH most of the time). Skin would dry anyway because water evaporation rate is proportional to a pressure (hence temperature) difference and convection makes a constant supply of fresh unsaturated air.

Relative Humidity is relative to temperature. Cold air can simply hold less water overall, at 20C it can easily hold double as much water as it can at 0C. There being a pressure difference is nonsense, you can get the same air pressure in the winter as in summer (though it tends to go on the Low side more often). What you probably mean is the vapor pressure, ie the natural pressure the liquid wants to be at in a clos…

I think the relevant pressures are the vapor pressure of liquid water, the atmospheric pressure, and the partial pressure of gaseous H2O at the gas-liquid interface.

If you can blow dry air over its surface, you can evaporate liquid water (or sublimate water ice) even when the relative humidity is 100%.

You can think of air as a gaseous solution, and its water vapor content like table salt in aqueous solution. Temperature affects the solubility, and if the solution is saturated, no more can dissolve. You can still dissolve salt crystals sitting in a saturated cold saltwater solution by squirting warm freshwater onto the bottom of the container. If that then mixes with the rest of the solution, and everything cools down again, that dissolved salt can then precipitate out somewhere else (like rain), or form a suspension of tiny crystals (like fog or clouds).

The solubility of H2O vapor in atmospheric gas increases with temperature. But you can also do something with a gaseous solvent that you can't easily do with a liquid solvent, which is to change the pressure. Higher pressure lowers the solubility of water in air, but to a far lesser extent than a decrease in temperature. Even though the vapor pressure is dependent only on temperature, evaporation occurs whenever the vapor pressure exceeds the partial pressure of H2O at the interface. Increasing the overall air pressure also increases the partial pressure of H2O vapor by a proportional amount, so inhibits further evaporation. But water vapor is also less dense than N2, O2, and most other atmospheric gases, so the means of measuring pressures gets complicated.

When you involve wind, and stratified airflows, it gets even more complicated. The air blowing across water or water ice could have been previously warmed by the ground just enough to evaporate more water, then get pushed higher by an angled snowbank into colder, saturated air, and it will then dump the excess water as small ice crystals. A solid block of ice can then become "rotten" as a snowdrift forms downwind of it. The overall average temperature may say that ice should stay frozen, but the wind can still carry a tiny bit of water vapor at a time, thanks to local fluctuations, and with enough volume of air to move it, that ice will drift.

Re: Build a do-it-yourself home air purifier for about $25

#318

Earlier quoted context omitted.

Does it spew out ozone? My memory may be off but I remember this model not meeting CA air purifier standards which was why Amazon couldn’t ship it to me

no, there is no ozone generator in this model (usually that's done using electrostatic plates).

I'm still curious then as to why this specific unit doesn't meet California air purifier standards, which is why Amazon won't sell it to me.

Re: Build a do-it-yourself home air purifier for about $25

#319

Earlier quoted context omitted.

What? That's an insanely uncomfortable indoor temperature. Anything over 20 and I'm uncomfortable.

What is the humidity level in your house? 25ºC should be comfortable for an healthy individuals if the hair is not heavy with humidity.

Bwahahahahaha... air

Re: Build a do-it-yourself home air purifier for about $25

#320
post #193

Earlier quoted context omitted.

Very interesting! How does the Dylos 1100 Pro compare to, for example, the Nova SDS011 sensor? By my cursory review, the SDS011 is much cheaper and appears to offer a more native Raspberry Pi-compatibility experience. Is the Dylos more precise? Can it produce readings the SDS011 can't? Are the two sensors measuring fundamentally different things? Finally, if you had to do it all over again, would you choose a differe…

SDS011 is the basis for luftdaten.info; have a look here for a diy guide (optionally including humidity/temperature as well): https://luftdaten.info/en/construction-manual/

Hi, this is an interesting project. It seems to be targeted for outdoor measurements. Do you know if this also suitable for indoor measurements (meaning if you want something for indoor air quality, would you measure the same things?)

I recently watched a video from dhh (https://youtu.be/MRqh8oLY7Ik) about air quality at home and was thinking if there was a nice diy solution for measuring it.

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