VOC & Formaldehyde Correlation

Many times I have mentioned that a simple VOC sensor isn’t enough to determinate if the air quality is good or not especially in interior environments. Formaldehyde CH2O is a VOC and since I have an AQ monitor uRAD A3 that features both a Formaldehyde sensor and a VOC sensor I will try to find out if there is a correlation between them.

I have been monitoring my house for Formaldehyde for over a month now by leaving the AQM on including while I was out on a trip for 4 days and during that time the house was well closed. This kind of experiment allowed me to determinate if my furniture, paint, etc outgassing Formaldehyde.

The measurements below were taken from 11-March to 15-March 2018. You can immediately notice that there isn’t any correlation whatsoever. Some spikes of CH2O (the blue line) were actually due to the wine I used during the cooking process. The alcohol can interference with the CH2O sensor.

11-15 March 82000068 CH2O vs VOC-3.jpg

There is some low concentration of CH2O in my house between 0 and 0.1ppm totally acceptable by me.

Interesting observation, there was some correlation between Formaldehyde and Carbon Dioxide CO2. As a result, remember to open your house windows if the outdoor conditions are good.


All in all, we can’t make assumptions about the indoor air quality just with a VOC sensor. VOC sensors are also vulnerable to interference by other gases in the atmosphere, so by having a narrow sensor that only measures one gas we can be more sure about the air quality.


One thought on “VOC & Formaldehyde Correlation

  1. […] Now, the EPA does not set standards for exposure to VOCs, so there is no known “safe” level that you can just kind of ignore. Moreover, although there are air quality monitors out there that claim to measure VOCs in the air, these may not be accurate, and it may not be enough to just know total VOC levels without knowing what they’re made up of (read more on that from Sotirios at See the Air). […]


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s