Poor Air Quality - High AQI

[black_son_of_gray]

For a chic look crossed with DIY, you could make the box in the style of a Japanese andon floor lamp...throw a couple of LEDs inside and add kumiko panel inserts so that the HEPAs look like rice paper. (Do they pass light or are they too thick?)

[jacob]

Ha! I actually thought about that but it would require adding a transformer and space is kinda tight in there/all the electrical parts are suspended from the lid. Not impossible though. Alternatively, a battery circuit on the bottom ... or just dropping a flashlight in there for special occasions

Other considerations would be to have an arduino poll a website for the current AQI and automatically start it over a certain threshold.

[Smashter]

Bravo, that looks really nice! My cuboid has been relegated to the basement in part because it is so unappealing to look at. Yours could be a living room center piece. At least according to me, I'd have to check with DW on that one

Most of the commercial solutions are 6 months or a year, but they generally have a screening filter in front of the HEPA filters. Those are supposed to be cleaned or replaced more often.

The writer who turned me on to all this stuff is of the opinion that the filters should last a lot longer than 6-12 months. Add even more time if you aren't running them 24/7. He doesn't give any guidelines as far as I remember though. It seems like a case by case thing where you judge it by how filthy it is.

I ran my version of what Jacob built basically 24/7 while living in a Brooklyn apartment with relatively poor air quality (PM 2.5 levels of between 8 and 50 if I didn't have any filters running.) They were still working after 12 months, but we decided to replace them when we moved because the filters were getting noticeably dirty and it felt like a good time to freshen them up.

It would be interesting to also build your own screens and see how that affected the lifespan. As for my Coway, which as I mentioned before is still an absolute beast despite having a 1.25 year old filter — I clean a significant amount of dust off the screen every 2-4 weeks.

[jacob]

I borrowed @Smaster's fancy smell-o-meter and took some readings over the past couple of weeks.

Quick lessons learned:

• If the windows are fully open, the inside AQI is the same as that reported on various weather sites. IOW, opening the windows provides enough circulation to replace the indoor air faster than the outside AQI changes.
• We have an unvented kitchen with a gas stove. Running the oven easily puts the AQI up to 250. I can see why various government nitpickers want to make ducting mandatory/get rid of gas stoves. Modern sealed housing turns those home interiors into Canadian wildfire air resulting in rather heavy long run health costs in the aggregate.
• I can smell---smell may not be the right term, taste, insofar one can taste the air, may be better---the difference between 25, 50, 100, and 200 without needing an instrument. 200 feels like "I don't want to breathe this stuff". 25 feels "super clean"(*). It's nice to get this "feeling" confirmed by an instrument.

(*) Usually not an experience one gets around Chicagoland.

As for the longer lesson, I decided to run the DIY purifier and take regular measurements.

Here are the results:

Code: Select all

Outside 9am: PM2.5=38.9/PM10=64.5/#=5732/AQI=109 (Overcast, no wind) 
Wunderground Forecast: AQI=40 (first time seeing a mismatch)
Upstairs  9am: 19.5/29.5/2900/67
Purifier is switched on downstairs, measurements taken upstairs
Upstairs 10am: 18.6/28.8/2810/64
Upstairs 11am: 15.5/22.9/2247/56
Upstairs 12pm: 13.0/18.4/1953/52
Upstairs  1pm: 12.2/17.9/1885/51
Upstairs  2pm: 12.0/17.6/1812/51
Exhaust:      2.9/3.0/456/12
Downstairs:   5.9/8.0/813/24
Upstairs  3pm: 11.1/15.8/1694/45
Upstairs  4pm: 11.1/16.7/1704/45

Next morning 7am downstairs: 9.3/12.6/1367/39
Next morning 7am upstairs:   9.1/12.7/1397/37

Comments: Our windows are mostly closed except a few (bathroom, kitchen). I closed all of them for the experiment. I put the purfier downstairs and took most measurements upstairs. Our 2 story + basement house definitely has a stratified atmosphere that is thermally balanced. Basically, each floor gets 5F warmer as you go up. This is sufficient to prevent clean air from the living room (where the purifier was sitting) from convecting upstairs. (Convection is by far the most effective way of mixing gases. Think mixing cream into coffee with a spoon vs just waiting for it.) The mixing still happened eventually as can be seen from the next day measurement taken 22 hours later. Meanwhile, the air was quite clean next to the purifier (exhaust) as well as in the room. Enough to "taste" the difference. I think the reason the exhaust wasn't 100% clean was that my purifier isn't sealed/caulked. There are some gaps around the filters.

Weirdness: The numbers don't appear to change much from 1 to 2pm and again from 3pm to 4pm. Not sure why.

Conclusion: Best put the purifier close to whether you need the clean air. Alternatively, you have to have fan(s) capable of circulating the entire house.

Note: My DIY monster is rather loud. I'd compare it to an window AC in fan-mode. The finished version seems louder than the unmounted fan. I don't know if this is because the fan struggles to pull the air (and there's therefore a load on the motor) or because the motor is mounted solidly on the lid and thus reverberates the entire box. The former can be solved by using a smaller fan/larger filters (rebuild). The latter by putting in some noise insulation in strategic places.

[Scott 2]

The data makes a good argument for dispersing small units through the home.

Interesting how quickly opening a window reverts to outside AQI.

We've got an unvented gas stove as well. Cracking the window when running it looks worthwhile. For all my concern over smoke, that might be causing more harm.

[jacob]

The data makes a good argument for dispersing small units through the home.

Alternatively putting a "good" filter on the HVAC. However, this requires a strong fan. The one time we tried using a "good" filter, the furnace fan really struggled.

[ertyu]

The data makes a good argument for dispersing small units through the home.

yes. the done thing is to have one per room.

[Gilberto de Piento]

Some thoughts:
You can program many smart thermostats to run the fan for part of every hour to circulate air through the filter even when heating cooling is not being used.

Similarly, some smart thermostats have air quality monitoring built in. I don't know the details of what they measure or what is reported though.

If you are worried about air quality you should also look into radon testing and mitigation. Radon is a significant cause of lung cancer. You can buy an electronic monitor to check your home or get a one time chemical test. To get a rough idea of whether it is a problem in your area I believe the EPA has maps. Or pay attention to houses as you are out walking. If you see houses that have a PVC tube come out of the side of the house, go into a motor, then go up to the roofline the house has a radon system. If there are a few in the neighborhood you probably need one too.

Someone posted some interesting links above about the cuboid diy filter. On that same website there was also an article about ultrasonic humidifiers causing bad air. That was a surprise to me.

For those building a diy filter with a cheap duct booster fan note that there are more expensive booster fans that are much quieter. Example https://acinfinity.com/duct-fan-systems/. Maybe better to buy a non diy item at that point though, I don't know.

[Jean]

maybe move where the forest already burnt?

[zbigi]

BTW this issue signifies the difficulty of making decisions based on models and forecasts, when the phenomena at hand are hopelessly complex. On this forum, some people preferred to move to northern parts of the US, because the southern part will be hit by climate change. And now, it seems that southern parts are still fine, whereas northern parts are already significantly impacted by climate change (assuming the forest fires come from climate change). It's just that nobody included forest fires and air quality degradation in their models and decisions.

[Gilberto de Piento]

maybe move where the forest already burnt?

The smoke is often coming from more than 1000 miles away.

[Gilberto de Piento]

(assuming the forest fires come from climate change).

It seems like fires can be attributed to some proportion fire suppression and some proportion climate change. It doesn't seem like this is an exact, settled science though. https://www.niskanencenter.org/megafire ... anagement/

[jacob]

BTW this issue signifies the difficulty of making decisions based on models and forecasts, when the phenomena at hand are hopelessly complex. On this forum, some people preferred to move to northern parts of the US, because the southern part will be hit by climate change. And now, it seems that southern parts are still fine, whereas northern parts are already significantly impacted by climate change (assuming the forest fires come from climate change). It's just that nobody included forest fires and air quality degradation in their models and decisions.

Anecdotally (many many books and concerned individuals), forest fires were included in the sense of people avoiding potential burn zones, but smoke spreading over half a continent was not.

People tend to feel the impact according to how much it differs from their expectations and preparation. Thus people in the midwest and northwest smelling smoke (from California and Canada) and seeing brownish skies for a week or so this summer was a big deal for those who otherwise considered themselves "out of reach"(*). Meanwhile, impacts in the south are an ongoing thing to the point where it's normalized as an "uncomfortably hot summer" (except normal summers are now this way; one power failure away from a health care situation that looked like the early days of COVID---think old people and small children---except with heat stroke.).

(*) For something this complex, humans often file it away mentally as "something that happens to other people, not me". This is even the case for many who take this seriously. It remains something abstract for them ... until it knocks on their front door.

Here's a map of what it costs: https://www.climate.gov/media/14993 This is real money coming from somewhere. Insofar federal bailouts are not forthcoming, it will affect local prices like real estate, infrastructure, services, tax base, and economic growth. What's happening currently is that several major insurance companies are getting out of home insurance in several southern states (also California). Without home insurance, no mortgage. Without available mortgage lending, lower RE prices because fewer can pay cash. With declining RE prices, enough people leave, the tax base gets reduced, the local government can't meet its obligations, and eventually its debt rating is downgraded, and city services decline.

Anyhoo ... AQI is relatively easily solved (cost ~$100) as demonstrated in this thread. It's the big outlier costs that are more worrisome in terms of loss of life and/or capital(s). I can build an air purifier. I can't stop a storm surge or deflect a tornado.

[Slevin]

What's happening currently is that several major insurance companies are getting out of home insurance in several southern states (also California). Without home insurance, no mortgage. Without available mortgage lending, lower RE prices because fewer can pay cash. With declining RE prices, enough people leave, the tax base gets reduced, the local government can't meet its obligations, and eventually its debt rating is downgraded, and city services decline.

I’m not sure if this is what’s happening in the Southern states, but in CA what is happening with the insurance is that there are swathes of the state with extremely high risk for wildfire / floods / etc (see Guerneville which floods and destroys half the town every ~7 years, literally the houses are all on one story high stilts, where the ground floors are not allowed to be anything other than garages), and the insurance companies rightfully don’t want to insure them.

But the state government made it so that they offer to be an “insurer of last resort” sort of deal (I think this might be limited to $1M / per house, but I can’t completely confirm that) for many of these properties, and every company who writes insurance policies in the state has to contribute to the bucket of costs whenever something horrible happens to these people who choose to live in places with incredibly high risk.

And to add onto that, insurers in CA aren’t allowed to just “raise rates to account for risk”; to do that, they have to do a whole complicated government process where they prove to the regulatory body that costs / risk went up, and then they can match a rate increase to that update. However, the overseeing body is less likely to approve huge changes, and so now there is something like “rent control” happening in CA over insurance prices.

So given the tail risk of costs involved, and the meager / nonexistent profit, insurers just decided to pull out of the state. Kind of an intersection of over-regulation mixed with some climate risk than just a straight climate change issue (but obviously the fire risks are increasing, etc, and that should increase costs and discontinue policies in the extreme risk area). There is a lot of talk of trying to fix it right now.

[jacob]

This is sufficient to prevent clean air from the living room (where the purifier was sitting) from convecting upstairs. (Convection is by far the most effective way of mixing gases. Think mixing cream into coffee with a spoon vs just waiting for it.) The mixing still happened eventually as can be seen from the next day measurement taken 22 hours later. Meanwhile, the air was quite clean next to the purifier (exhaust) as well as in the room. Enough to "taste" the difference. I think the reason the exhaust wasn't 100% clean was that my purifier isn't sealed/caulked. There are some gaps around the filters.

The outdoors smelled like a coalfire today, so I started the filter for the first time since building and testing it. I found that switching on the HVAC in fan-mode solves the circulation problem. Rather than having ultraclean air in a corner of the living room, which takes many hours to reach the rest of the house, the furnace fan/duct-system was able to distribute it around fairly quickly (<10 mins).

[chenda]

What's caused that Jacob ?

[jacob]

My best guess is thermal inversion in the atmosphere (due to the heat reservoir in the nearby giant lake) trapping and concentrating the standard human emissions near ground level.

[Smashter]

The inimitable blogger Dynomight, who started me down the air quality rabbit hole, mentions and responds to one of my posts from this very thread in his recent link roundup on his blog (it's number 11).

It was an interesting, world's colliding type experience to read the post. As I got to the 11th link, I was like "Dang, that sounds similar to what I wrote on ERE. Wait, it is what I wrote!" Ha. Good times. Here's what he said:

Here’s a cautionary tale from someone who caught my obsession with air quality and built a Cuboid.
[quotes my post above]
This is a good story, but a couple notes: (1) If you go by the listed clean air delivery rates, the Coway purifier should do more than all the other purifiers combined (at higher cost). (2) There’s nothing wrong with commercial air purifiers! I just think it’s weird that manufacturers don’t provide more evidence that their products actually work, given that they’re borderline unregulated and tests suggest some don’t work as advertised. (Also I don’t scoff that much.)

Thanks for the response, Dynomight. If you lurk around these parts, pop in and say hi sometime There are lots of people here who would enjoy nerding out on air quality and plenty of other topics with you.

[Cam]

Very interesting. I just got myself a Coway, but the smaller Airmega 150. It is working wonderfully, and has helped keep me healthy even as people in my household have been getting sick repeatedly. My girlfriend has it down at her apartment right now, as she's having a get together tonight. It's one of those measures to keep healthy that people don't object to, because it just sits there, quietly filtering pollutants out of the air.

I may look at DIYing a filter for the coming forest fire season - much cheaper but not as pretty to look at. I liked what Jacob made with the wood frame - it is far more aesthetically pleasing than the normal DIY filters. I don't care about aesthetics, but the people who I live with do However I know the standards are lowered when we're peak forest fire season and the haze is visible inside the house - at that point I don't think people will care what the filter looks like as long as it cleans up the air.

[AxelHeyst]

I got a small blower (centrifugal fans produce more dP than axial fans) and strapped a tiny HEPA filter on to its intake.

I don't have an AQI monitor, but I get total-face-explosion-level pollen allergies in spring and fall, and with this thing blowing at my face I get immediate relief. It's easy to move it around to wherever I'm at -- sitting at desk, lying in bed, reading in a chair, etc. I even brought it with me in a car a few times, plugged it into a small inverter and had it in my lap blowing up at my face.

I wonder what the AQI of the airwash over my face is in a smoke event is? I bet it's better than nothing... but how much better?

This is the air quality version of using smaller devices to heat the humans in a room as opposed to the entire room. I don't need all of the air in my space to be clean, I need the air I breathe to be clean.

This device is 11w, fan was $20, filters are $5/per. I could have build a neat box for it, in fact I was planning to, but electrical tape worked fine. The build was 30seconds.