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UK house owner here.

One of our ground floor rooms has a damp issue from below, due to poor damp proofing. We can't fix the problem immediately until we have finance.

Apart from a musty smell and around 75% humidity it's not an unsightly room. We thought reducing the humidity levels would be a good interim step.

Bought an air quality monitor that measures temp, humidity, PM, CO & VOCs.

Bought a MeacoDryArite One 25L dehumidifier, and set it to a 45% target.

Before turning it on all indicators on the monitor were around zero, except temp (67c) & humidity (70-75%). The monitor itself had had about 48hrs to acclimatise.

Within around 2-3hrs the Meaco had done a great job. Temp was stable & Humidity went to around 50%. However to my alarm the VOC Index went crazy.

It jumped up to 48/100...declined to about 10/100 after 1hr, and went up again to about 35/100 after around a total of 6 hours.

So here's my question - why would VOCs increase if humidity is decreasing, and should we terminate the dehumidifying altogether? I'm concerned it could affect our health?

P.s. we've not opened any paint or new furniture etc. Nothing has changed except running the dehumidifier.

Foxtonian
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3 Answers3

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My guess would be that your newly purchased dehumidifier is off-gassing and producing the VOCs that are being detected.

From Google:

A lot of plastics in the home are made from polyvinyl chloride (PVC). Although manufacturers claim that products made with PVC do not release vinyl chloride vapor, they can off-gas VOCs known as phthalates.

You might try running an air purifier in conjunction with the dehumidifier and see if the issue resolves.

matt.
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Another guess would be that the when you remove moisture from the air, it is less saturated and items in the home emit more VOCs.

These can be

  • Paint
  • Flooring
  • Rugs and Carpets
  • Insulation
  • Furniture
  • Cleaning Products
  • Other items such as hair sprays and air freshners

Apparently safe levels are less than 0.5mg/m3 from TECAM. Try converting your readings to the same units for comparison.

Rohit Gupta
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I am conducting a science experiment with my daughter and we found similar findings. The baseline TVOC and formaldehyde levels in the room were 0 and .001, respectively. When the dehumidifier was activated concurrently with an air purifier (HEPA/charcoal filters), the TVOC and formaldehyde levels remained elevated and plateaued, but did not return to zero until we stopped the dehumidifier. The dehumidifier is clearly emitting VOCs and significantly raising CO2 levels as well.

Arpa Baroni
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