Blown-in-Cellulose Insulation

/ / Green Building Consulting, Healthy Building Inspections & Testing
blown-in-cellulose insulation

Blown-in-Cellulose Insulation Test Results

On a recent project, we recommended a homeowner try Blown-in-Cellulose insulation as a healthy alternative to other insulation choices. Blown-in-cellulose is known in the healthy materials world as a pretty safe insulation choice. But just to be sure the product was safe, we sent a wet sample to a lab for emissions testing.

Blown in Cellulose Insulation

Blown in Cellulose Insulation

First, we asked that the sample be wetted with water (instead of a solvent) to avoid introducing additional chemicals to the mix. We also asked that it be sent to the lab wet, presumably to get the “worst case” scenario of emissions from a sample that was not yet dried.

When the lab results  for the blown-in-cellulose insulation were returned to us, we were a bit concerned to see the following:

Lab Results Cellulose

Lab Results Cellulose

Formaldehyde? Acetaldehyde? Toluene? This was not what we had expected. And half of the house had already been insulated with blown cellulose and the walls closed! Fortunately, we held off jumping to conclusions until I’d had a little time to assess the results.

In order to get a better sense of the data, I looked up the acceptable limits allowed by a certification generally considered to be the most stringent in the industry: GREENGUARD. The Full Concentration Levels applicable for Building Construction Materials and Finishes are as follows:


Parameter GREENGUARD Full Concentration Level applicable for Building Construction Materials
Total VOCs (TVOC)

≤ 0.5 mg/m3


≤ 0.05 ppm

Fortunately, there are a lot of online calculators – that explain how to convert from ppm to mg/m3.  But the first calculation did require looking up the molecular weight of formaldehyde—it brought back memories of college chemistry class!

Here is the equation to convert between ppm and mg/m3:

ppmformaldehyde = (mg/m3)formaldehyde * (24.45)/(molecular weight)formaldehyde

So I plugged in the following values to solve for x, the GREENGUARD formaldehyde limit in mg/m3:

0.05 ppm = GREENGUARD formaldehyde limit

30.031 g/mol = molecular weight of formaldehyde

24.45 = conversion factor

x = GREENGUARD formaldehyde limit in mg/m3

Solving for x, I found the formaldehyde limit set by GREENGUARD in mg/m3:

x = 0.0614 mg/m3 = 61.4 µg/m3

The formaldehyde levels from the test results (12.7 µg/m3) are at 20% of those allowed by GREENGUARD (61.4 µg/m3).

So, here is the final tally:



Total VOCs (TVOC)

101 µg/m3

≤ 500 µg/m3


12.7 µg/m3

≤ 61.4 µg/m3

It is good to know that blown-in-cellulose insulation is indeed a low-emitting product!