# Question: How can i know if my plant-based air filter is working?

liz asked on September 26, 2016 15:43
181 | 2 answers | #13482

I am planning on making https://publiclab.org/notes/nshapiro/09-26-2016/build-a-plant-based-air-purifier, and i'm wondering how i can know if it's even doing anything to improve my indoor air quality?

One method would be to measure various air quality parameters before starting to use the plant remediation unit and then successively over the course of weeks or months during its use. The key points here would be that you would need (1) to know what the most appropriate air quality parameter or indicator would be for your situation (e.g. formaldehyde, carbon monoxide, particulate matter, benzene, etc) and (2) have a reliable instrument and method for measuring that air quality indicator. If you're just interested in getting a sense of whether or not it's working at all, a qualitative or somewhat imprecise or inaccurate method may be perfectly fine.

Another potential method would be to keep a log of health symptoms starting before use of the plant remediation unit and continuing throughout its use. The primary benefit of this method is that it focuses on your health, which is likely the underlying purpose of using a remediation unit. The primary drawback of this method is that it can produce the "placebo effect" where you may trick yourself into thinking it is working when it's actually having no effect, or you may trick yourself into continuing to feel sick or fatalistic, but it's actually working quite well. You could perhaps invite a friend who doesn't know about your plant remediation unit plans to visit for prolonged periods of time and ask them about how they feel, but again, that is highly subjective.

Any other ideas? Has anyone heard of visible changes in the plant roots? There are some plants that could be planted in an indoor garden that may provide insight due to their sensitivity to airborne contaminants. Perhaps planting some of these at various points in time, and monitoring their health and vitality (or lack thereof) could be indicative of the air quality? Here's one resource about plants that are sensitive to different air contaminants, but there are many others too: https://www.apsnet.org/publications/plantdisease/backissues/Documents/1982Articles/PlantDisease66n05_429.pdf.

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Those are great answers @gretchengehrke ! I think we should write both of them up as activities to be replicated in the Open Air initiative. The replication in GA was all three activities (making, device testing, body as sensor testing). I wonder about the ethics of inviting over a friend as a control though.

I'm less concerned about the placebo effect because 1) for subclinical symptoms abatement is subclinical symptom abatement. "Side effects" are still effects. 2) people who will try this will have likely tried a million other things first without success--could we capture that as a way to stave off placebo effect critiques? and 3) because the assumption of placebo effect is part of the expert dismissal of self assessments when studies indicate lay individuals are better at assessing changes to their own health better than MDs.

Do you want me to draft up two research notes to be set as activities on that and run them by you?

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Wouldn't you need matt's setup and the sampling tubes? how much would it cost to run 3 tubes for formaldehyde before, and 3 tubes for formaldehyde a month after you've cared for your plants and built your setup?

S

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Yeah, that would totally be an approach (and an affordable one, with ~$20 for kit plus 6 x$7 for tubes), but those tubes are not as formaldehyde-specific as you'd hope. The chemicals covering the beads would really react with any aldehyde or ketone, with varying reaction speeds due to things like steric hindrances, making it a non-quantitative option. We tested the tubes against the EPA method that quantifies formaldehyde, acetone, and acetaldehyde in a sample, and verified that the tubes do indeed react with those other co-contaminants: https://publiclab.org/notes/gretchengehrke/10-07-2015/formaldehyde-measurement-testing-public-lab-s-kit-with-doh-s-equipment

@gretchengehrke when push comes to shove would you want the Kitagawa based system to be an activity for assessing the efficacy of the purifier? in your comment above you note that qualitative measures could be fine, and also our kit was good at reproducing finding in the same place so could be good for assessing change even if the exact ppb quantification is off. That said, I'm pretty wary of asking anyone to make that kit on their own as it is super time intensive if you use the bubble flow meter and somewhat expensive if you use the rotometer, and as we should have something much better and cheaper in 6 months i have a bit of extra hesitancy. So I'm on the fence erring towards lets wait till we see what we can do with this current NSF project (that i need to announce-- oops!)

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