[HN Gopher] Rethinking indoor air chemistry
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Rethinking indoor air chemistry
Author : giuliomagnifico
Score : 84 points
Date : 2022-09-05 09:53 UTC (1 days ago)
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(TXT) w3m dump (www.mpg.de)
| musha68k wrote:
| Somewhat illogical that after more than two years into the
| pandemic HEPA filters are still a rare sight to be seen indoors.
|
| So chemical compounds in general yes, but especially aerosols-as-
| viral-vector still pose a threat:
|
| https://elpais.com/especiales/coronavirus-covid-19/a-room-a-...
| ceejayoz wrote:
| > Somewhat illogical that after more than two years into the
| pandemic HEPA filters are still a rare sight to be seen
| indoors.
|
| I think we'll look back at this particular thing as one of the
| greatest public health failures in quite some time.
| colineartheta wrote:
| Can you name a greater one?
| ceejayoz wrote:
| Not banning smoking probably is up there.
| crazygringo wrote:
| Really? I feel like they've popped up everywhere, never seen so
| many air filters in my life.
|
| I feel like every doctor's reception area, daycare, dance
| studio, meeting room... every little public room that doesn't
| have HVAC has a little air filter in the corner or on a side
| table. Often one the Levoit air purifiers that got so crazy
| popular on Amazon.
|
| As to whether they replace the filters regularly enough, I have
| no idea... I also figure they have little-to-no effect when 20
| people are in the room and its fan is on its weakest (quietest)
| setting.
| Cupertino95014 wrote:
| Granted that not everyone lives in a friendly climate:
|
| * What's the effect of occasionally opening a window? I'm not
| talking about all day when it's 20F or 105F outside, but for half
| an hour at least.
| ladberg wrote:
| Not exactly what you're asking but here's an anecdote:
|
| I recently got an air quality monitor because I was worried
| about CO2 levels in my apartment having the windows closed and
| AC running all day every day. It turns out the levels were
| higher than I'd like (nearly 2000 PPM) and just cracking a few
| windows open very slightly, less than an inch, is enough to
| reduce the concentration to between 400 (outside air) and 900
| depending on how many people are home. The window AC unit was
| still able to handle cooling the apartment with a relatively
| small change in usage.
|
| I also run an air filter constantly so my PM2.5 and PM10 levels
| were already near-zero, but I'd imagine cracking a window helps
| with that.
| rhd wrote:
| I went down a similar journey over the last couple years
| (CO2, VOC, PM1.0/2.5/10 sensors). In my apartment I sit
| around zero for particulate with windows closed. I jump up
| significantly with windows open unfortunately (for my
| allergies) in the midwest.
|
| I do wish my AC/Heat had more air exchange, similar to your
| space my CO2 levels rise dramatically after an hour or two of
| occupation with windows closed.
| Cupertino95014 wrote:
| I'm just waiting for a "green building" code to specify "all
| windows shall open."
|
| Imagine the panic _that_ would cause in the construction
| industry.
| danans wrote:
| Building codes already require operable windows, and some
| local codes now require active ventilation systems.
| Cupertino95014 wrote:
| The stock of office buildings probably turns over fairly
| slowly. I've actually _never_ worked in an office where
| the windows opened.
| abstract_put wrote:
| I think generally "green building" (at least the mainstream
| stuff) focuses on insulation + air tightness, and then
| mechanical ventilation. In that context, operable windows
| would be mostly be a "just in case of overheating" or
| similar, and the expectation would be CO2 et al would be
| managed by the ventilation.
| elina123 wrote:
| giantg2 wrote:
| I think my potent chemicals are coming from sources other than my
| skin and breath.
| ballenf wrote:
| Could the shift away from full spectrum incandescent bulbs have
| any affect on the "air cleaning" process indoors?
| danans wrote:
| > Ozone was added to the chamber air inflow in a quantity that
| was not harmful for humans but representative of higher indoor
| levels
|
| Just in case anyone reads this and is thinking about buying one
| of the ozone emitting "air cleaners":
|
| https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...
|
| "The same chemical properties that allow high concentrations of
| ozone to react with organic material outside the body give it the
| ability to react with similar organic material that makes up the
| body, and potentially cause harmful health consequences. When
| inhaled, ozone can damage the lungs"
| Chris2048 wrote:
| Maybe they can be used while rooms are not occupied? That said,
| would there be any wear/damage on items within the room?
| danans wrote:
| > Maybe they can be used while rooms are not occupied?
|
| Yes, but a simple exhaust fan in a window could also be used
| without any risk to the occupant. If there's no window, then
| one should definitely not introduce ozone.
|
| > That said, would there be any wear/damage on items within
| the room?
|
| "Ozone can cause substantial damage to a variety of materials
| such as rubber, plastics, fabrics, paint and metals. Exposure
| to ozone progressively damages both the functional and
| aesthetic qualities of materials and products, and shortens
| their life spans."
|
| https://ww2.arb.ca.gov/resources/fact-sheets/ozone-
| effects#:....
| cma wrote:
| It does much more than airing out. It will completely clear
| up cigarette smell from an apartment that had indoor
| smoking. It neutralizes. All the gunk that built up from
| it, similar to how it degrades rubber.
| danans wrote:
| > It does much more than airing out. It will completely
| clear up cigarette smell from an apartment that had
| indoor smoking
|
| As will surface cleaning and repainting porous surfaces
| that held the cigarette tar, but without the side effects
| of ozone like the release of additional VOCs from other
| materials it reacts with. Either way, completely airing
| out the space is a necessity.
| cma wrote:
| You're not going to repaint carpet.
| danans wrote:
| No, but deep cleaning it with a machine or replacing it
| are possible.
| thfuran wrote:
| Possible...and way less convenient and way more expensive
| than just putting some ozone into the air.
| danans wrote:
| They are undoubtedly different solutions with very
| different outcomes. This discussion has been good for
| laying out the pros/cons.
| brnt wrote:
| Do you seriously leave smelly carpet from previous owners
| in place?
| [deleted]
| giantg2 wrote:
| Seems a little odd. I guess they mean it's just not acutely
| harmful?
|
| I have an ozone generator. I use it occasionally and never in
| the same room. It's pretty useful for clearing out odors as
| long as you air out the space afterwards to help the ozone
| dissipate.
| danans wrote:
| > It's pretty useful for clearing out odors as long as you
| air out the space afterwards to help the ozone dissipate.
|
| You can skip a step and clear the odors just by airing out
| the space.
|
| If the odors are of the type and quantity that airing out the
| space isn't sufficient, the issue to deal with might be the
| source of the odors.
|
| An air filter with activated carbon can also help reduce
| odors.
| coryrc wrote:
| I had an RV which was previously housing mice. After
| removing and Killz, it still smelled. Two days with the
| ozone and it was fine after.
| jpk2f2 wrote:
| Worked well for me as well in mildew-y car, still had a
| smell after replacing all carpet and cleaning every
| reachable surface. Ozone with air running for an hour
| resolved it nicely.
| causi wrote:
| I worry about ozone generators degrading electrical
| components, especially wiring insulation and sensors.
| giantg2 wrote:
| That's generally a non-issue if used occasionally and at
| reasonable levels.
| danans wrote:
| If it still smelled it is because the waste of the mice
| remained in the RV. The ozone didn't remove the waste,
| but probably just reacted with it to neutralize the odor
| causing VOCs.
|
| If you were ok with that state, that's great, but
| eliminating the source of the odor tends to be more
| effective way to deal with it.
| coryrc wrote:
| According to you, I should have removed every bit of
| structural material and flooring because the ozone "only"
| neutralized it? You do realize odors _are_ VOCs, right?
| Ozone destroyed them. It 's great.
| danans wrote:
| > You do realize odors are VOCs, right?
|
| Odors are caused by some VOCs. Some VOCs have no odor,
| including harmful ones.
|
| > Ozone destroyed them.
|
| https://pubs.acs.org/doi/full/10.1021/acs.estlett.1c00773
|
| Conclusion:
|
| "... this work shows that for at least some consumer-
| grade portable air cleaners that claim to remove VOCs
| from indoor air, VOC removal may actually be minimal, and
| the air delivered may contain additional VOCs and/or
| oxidation byproducts, some of which are known to be
| harmful to human health."
| smallerfish wrote:
| It kills off microbes, does it not? We live in a high
| humidity environment. When we shut up the house and
| travel for a couple weeks, there's inevitably a high
| amount of mildew on our return. I have been contemplating
| running an ozone generator on a timer while we're out of
| the house for an extended period to combat this.
| danans wrote:
| > I have been contemplating running an ozone generator on
| a timer while we're out of the house for an extended
| period to combat this.
|
| You would be treating the symptom, not the cause, with a
| harmful chemical that probably wouldn't completely
| eliminate the mildew, and have unknown side effects.
|
| It would be far better to install a dehumidifier and
| proper ventilation to manage the mildew problem than
| killing it off with ozone afterwards.
| smallerfish wrote:
| The house isn't sealed to the outside, and we don't
| typically run AC (or heat). A dehumidifer would just run
| all day and produce water without affecting the humidity
| in the house at all (again, because it's not sealed).
| Very different from US or European build quality. And
| yes, ozone would leak to the outside, but most of the
| venting happens from the top of the house.
|
| (For reference, there's a $50m house nearby for sale that
| has no exterior walls at all. It's being sold at a
| discount - only $12m! - because of a notorious incident
| that took place there, and the fact that the owner can't
| return to the country without risking arrest and a fourth
| trial.)
| danans wrote:
| > The house isn't sealed to the outside, and we don't
| typically run AC (or heat).
|
| Sounds like you are in or near the tropics. How do you
| control the mildew when you are at home? Presumably not
| with ozone, but with ventilation. Can you just have the
| house do that when you are not there also?
| smallerfish wrote:
| Yeah. Windows and doors open when we're home, typically
| (with ceiling fans to move the air). We definitely
| _could_ install whole house ventilation and leave that
| running, you're right - it'd just need to be done well,
| so could be spendy.
| darkteflon wrote:
| Have you considered something like Mitsubishi Lossnay[1]?
| The unit itself is not expensive. Also much cheaper to
| run than aircon and better for the environment.
|
| We're also in a high humidity environment with equally
| breezy construction standards and have struggled to keep
| the house mildew-free when we travel in Summer. We
| eventually settled on running a compressor-dehumidifier
| 24/7 during those times, but it's not perfect.
|
| We considered installing a Lossnay to create a consistent
| positive pressure gradient and help with humidity
| exchange, although in our case construction - although
| not extensive - is tricky as we're quite high up. You
| might be better off.
|
| [1] https://sg.mitsubishielectric.com/en/products-
| solutions/air-...
| giantg2 wrote:
| The ozone will destroy the odors, where the filter just
| traps some.
| danans wrote:
| It doesn't destroy odors in the air. It reacts with them
| to turn them into something else which maybe you can't
| smell. Moreso it can cause the creation of formaldehyde
| when it reacts with some chemicals in the air.
|
| It also inhibits the sense of smell and it can cause the
| accelerated release of VOCs from materials, which then
| enters the air.
|
| https://ww2.arb.ca.gov/our-work/programs/air-cleaners-
| ozone-...
|
| If it works for you, great, but it doesn't destroy
| anything.
| cinntaile wrote:
| If it turns one molecule into another then that's
| basically destruction.
| giantg2 wrote:
| "It reacts with them to turn them into something else..."
|
| Lol what do you think destroy means?
| danans wrote:
| Do you think the byproducts that result from the reaction
| with ozone are safer to breathe? If not, then you need to
| air out the room or filter the air, so why not just do
| that in the first place?
|
| Just because you can't smell something because it has
| been "destroyed" by being converted to something else
| doesn't mean it's not harmful to health.
|
| Again from the EPA:
|
| https://www.epa.gov/indoor-air-quality-iaq/ozone-
| generators-...
|
| "First, a review of scientific research shows that, for
| many of the chemicals commonly found in indoor
| environments, the reaction process with ozone may take
| months or years (Boeniger, 1995). For all practical
| purposes, ozone does not react at all with such
| chemicals. And contrary to specific claims by some
| vendors, ozone generators are not effective in removing
| carbon monoxide (Salls, 1927; Shaughnessy et al., 1994)
| or formaldehyde (Esswein and Boeniger, 1994)."
|
| "Second, for many of the chemicals with which ozone does
| readily react, the reaction can form a variety of harmful
| or irritating by-products (Weschler et al., 1992a, 1992b,
| 1996; Zhang and Lioy, 1994). For example, in a laboratory
| experiment that mixed ozone with chemicals from new
| carpet, ozone reduced many of these chemicals, including
| those which can produce new carpet odor. However, in the
| process, the reaction produced a variety of aldehydes,
| and the total concentration of organic chemicals in the
| air increased rather than decreased after the
| introduction of ozone"
|
| "Third, ozone does not remove particles (e.g., dust and
| pollen) from the air, including the particles that cause
| most allergies. "
| giantg2 wrote:
| Airing out the room won't remove the sources of odor.
| This can be stuff like smoke residue, stuff the carpet
| cleaner couldn't pick up, etc. I clearly advocated for
| airing the room out afterwards.
|
| Name me something physical that is actually "destroyed"
| (mind the laws of Physics). The use of the word is used
| to describe the destructive process that causes a
| specific thing to not exist, and almost always means it
| was turned into something else.
| danans wrote:
| > Airing out the room won't remove the sources of odor.
| This can be stuff like smoke residue, stuff the carpet
| cleaner couldn't pick up, etc
|
| The source needs to be cleaned from surfaces,
| encapsulated (i.e. by painting over it), or removed by
| disposing of uncleanable materials like smoke residue on
| carpets.
|
| > Name me something physical that is actually "destroyed"
| (mind the laws of Physics). The use of the word is used
| to describe the destructive process that causes a
| specific thing to not exist, and almost always means it
| was turned into something else.
|
| I don't think we disagree about the physics, only about
| whether the byproduct of the conversion resulting from
| oxidation with ozone can be harmful or not.
|
| If the citations I've provided haven't convinced you of
| the risks of using ozone generators for air quality, then
| by all means enjoy whatever methods work for you.
| solidist wrote:
| I wouldn't overthink it. Opening windows frequently is a good
| thing. Doing it during winter is even better. Oh and use
| crbon/hepa air filtering in bedrooms while sleeping.
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