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Comment by salex89 | Hacker News Reader

I've recently borrowed a similar device, and this one also measures formaldehyde. To be honest I'm quite anguished by it, because I can't find any indoors object with formaldehyde concentration less than 0.1ppm, which is the "safe" (by some legal standards) margin. Only outside or in a room with a wide open window it comes down under. It's even borderline higher in buildings not recently renovated. I've tried researching how dangerous is 0.3ppm or such, or how to keep it under control, but no luck. All sources are very academic...

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0.1 ppm is quite a high indoor concentration of formaldehyde. Most homes will not air exposure levels this high.

Just for reference, NIOSH recommends 0.016 ppm as the max exposure limit for a workday. CARB recommends a max safe level of 0.05 ppm. WHO recommends max level of 0.08 ppm for 30 minutes, etc.

0.3 ppm is extremely high for chronic exposure.

The meter is this one: https://www.amazon.com/Air-Pollution-Formaldehyde-Detector-T...

After these words I'm seriously starting to doubt the correctness of the device. I can't believe I wasn't able to find any indoor location with a low enough concentration for below 0.1 ppm, or only outdoors. I mean, these are rooms where I, my colleagues, friends and family are non-stop, we should all be good as one by now with those concentrations.

Looking at the link, this device measures formaldehyde in mg/m3. You'll need to convert this to ppm, just FYI.

1 ppm in air = 1.24 mg/m3 @ 25° C

If you're measuring 0.1 on the meter, that's about 0.08ppm (still pretty high).

It can show the measurement in ppm also.

However, I've read the reviews and dug a bit deeper, talked to some people. Basically, that value might be elevated by some unknown amount, but the device should not be trusted for the absolute levels.

I'm now curious enough to want to get one of the meters. The reason being that everyone at work swears by the new wave of "mattress to your door" mattresses that you can buy online. Buy I insisted on getting a "real" mattress filled made of cotton, wood and springs. I'm still looked at like a caveman because I didn't go for the extruded oil hipster mattress and would like to be vindicated by evidence from an impartial electronic device. If only for the rights to say "i told you so".

Equally if my so-called 100% natural mattress is giving of fumes, I'd like to know about it! Because I'm certain the living room furniture is doing so.

I was also curious, as an owner of a box mattress and laminate flooring.

I used https://acsbadge.com/ to do a highly-accurate one time test of my home and was happy with the results. Piece of mind to determine if you have a potential issue or not. They also give guidance on how to interpret the numbers and what 'safe' means (results are in ppm concentration accurate to 0.002 ppm).

That’s interesting, but they have 133 badges. Which one did you use?

https://acsbadge.com/product/formaldehyde-vapor-monitor-f-50...

Common sources of formaldehyde would be things like furniture, and another less obvious one would be air infiltration through your walls (picking the formaldehyde up from the engineered lumber) due to a depressurized home envelope (e.g. stack effect). When the house is depressurized enough to really draw in through the walls you should notice a puff of air when you crack a door.

What causes depressurized houses?

Most often the stack effect (warmth in the house causes air to rise & leak out the attic which sucks in replacement air down low- like a chimney), but also potentially overpowered range hoods, bath fans, clothes dryers, open flue gas appliances, wood fireplaces, etc.

Incidentally this is why there are limits on range hood CFM without makeup air (and there are broader recommendations on overall house design from groups like ASHRAE for air quality management). There are also whole-house leak tests in some regulations, e.g. Title 24 in California.

Typically it's around 300CFM before you should consider a mechanical make-up air device (gravity activated or a makeup air fan tied to the hood activating).

What device measures formaldehyde?

I've ordered an awair, I think it does vocs but not sure it does them in any specificity.

And I think the only real solution is venting. Open a window. Other than identifying the source and removing it of course. But in many places I think it's wall materials, furniture, etc

Dhh had a talk on indoor air quality you may find useful.

There are many devices out there on amazon, since formaldehyde inside your house == bad is a chinese health meme where air meters will measure it specifically.

https://www.amazon.com/Air-Pollution-Formaldehyde-Detector-T...

I am not aware of a consumer sensor that measures this accurately enough, but I'm also curious what is available.

I tested my home using a badge from this company: https://acsbadge.com/ They are not cheap ($60 for one test), but it's accurate to 2 ppb and will give you an idea what your chronic home exposure is and if changes are needed.

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