Here's some info i received from @nshapiro over email:

OSHA does regulate and test for formaldehyde but their levels are sky high and set in 1987: 750 ppb. NIOSH however has a TWA of 16 ppb, less than half of Mathew's recent test. http://www.cdc.gov/niosh/npg/npgd0293.html California says you shouldn't exceeded 27 ppb in a workplace (8 hrs x 5 days) and probably lower for a home. 8 ppb is the no adverse effects for exposures over a year. 8 is an important cancer risk threshold I believe--less sure about this though.

That the regulations are so out of touch with the experience of exposed people (I've seen reactions in the 10s of ppb for sensitized individuals) is a major motivator for the symptoms register part of wwb.

The newer the product the higher the level. Different products take different times to off-gas. Some a few weeks, some a few years. It's hard to measure the actual flux of how much a cabinet would emit, because the concentration would depend on room size and ventilation. Smaller the space and less ventilation the higher the levels. So popping a test kit inside a new cabinet would yield higher levels. (Maybe also preserve veggies better due to anti fungal hcho properties?)

Any positive or negative controls you plan to test against just to make sure the device works?

I know when I was using VOC detectors a long time ago, they would fall out of calibration very easily and for any reason, like, from sitting in a warm room for a few days. We always had to test and calibrate our gas detectors immediately before putting them into use.

Additionally, it was easy to overload one of the VOC detectors we had. After it went positive one time, it was positive even when using negative controls. The sensor had been overwhelmed and could only report positive from then on.

formaldehyde info from the Agency for Toxic Substance Disease Registry (ATSDR)

http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=39#12

See Minimum Risk Levels (MRLs), which a lot of these values are based on the same studies but the ATSDR does a good job of citing the studies and factors used.

I wish we had an info graphic to show which levels of formaldehyde are regulated by which agencies as compared to which levels of formaldehyde are correlated with human health symptoms.

Hey @liz! We have some of that information up @ http://publiclab.org/wiki/formaldehyde-exposure but you're totally right! We really need to make our own with regulatory levels on it.

@btbonval we are using an analog detection method to avoid the pitfalls of digital calibration. The tubes are sealed in the lab and read on the spot after a know amount of air is passed trough them. They have a reasonably high upper limit on them and (I believe, I'm on the road now with only my small device) if we reach our upper limit we can run the test for one third the time and multiply the result by 4 to be able to quantify even higher levels. But if we do get results that high, I think I would rather people just get out of there rather than take another sample. We do have some chemicals that could cross contaminate and make hcho results artificially higher or lower--getting a list a factors that could lead to the presence of these other contaminants would make or method stronger. Gretchen and I will be doing some field tests with the RI dept of health to validate and see about cross contaminants and the tubes themselves have already been validated in a labrotory setting. You are right that we need to worry about speciation. I think other Chem interferences is the final thing we need to do.

@nshapiro Calibration is calibration, be it analog or digital. Not sure why that distinction is made, but the rest of the statements are more heartening.

It sounds like the tube contains some reagent and is single-use?

I guess I missed the research notes which discuss anything about the mechanics of the sensor, so my questions might be lacking context.