How to control formaldehyde and other VOC off gassing in your indoor space

Volatile Organic Compounds, or VOCs, can affect our lives in unpleasant ways, and sometimes are hard to get away from, for example: 

• They can be in the glue that workers used to lay down flooring in your office or home

• In the oil-based primer that a contractor used to seal wood in a renovation

• You just ordered a memory-foam mattress and unboxed it.  As the heavy mattress expands to its full-size, you notice an overwhelming smell.  

If your sense of smell is telling you to get out of the space, it’s a good intuition, as most VOCs are unhealthy.  If you have the option to vacate the space (or even go on vacation!) while it “off-gasses” for a few weeks, of course that is best.  Otherwise, there are two options: 

1. If the object emitting the VOCs can be moved, move it to a ventilated space to allow it to off-gas there (increasing the temperature and humidity there will help)

2. If the object is un-moveable, control the emissions via: (IAQ and Your Health: A Deeper Look at VOCs and Formaldehyde Emissions)

1. Controlling the temperature and/or humidity

2. Using an air purifier that can adsorb the VOCs.

3. Seal the VOCs into hard objects such as furniture or flooring using a non-toxic topcoat like AFM SafeSeal or AFM HardSeal

4. Ventilating with windows, fans and heaters

First, let’s dive into how off-gassing happens and some differences between formaldehyde and most other VOCs.  

Formaldehyde is a simple organic chemical made of hydrogen, oxygen and carbon (chemical formula HCHO).  It’s a widespread and natural constituent of all living systems, found in plants, fruits, vegetables, animals (including humans) and seafood. It is one of the most abundant volatile organic compounds in the universe.  (IAQ and Your Health: A Deeper Look at VOCs and Formaldehyde Emissions)

The problem is being exposed to more formaldehyde than what is naturally-occuring.  You may have heard that formaldehyde is a probable human carcinogen, therefore, it’s best to avoid products that have formaldehyde added in. There are several ways of using formaldehyde in manufacturing: it can be reacted with phenol, urea or melamine.  Phenol-formaldehyde (PF) and melamine-formaldehyde (MF) resins are safer because they emit less formaldehyde than urea-formaldehyde (UF) resins.

At normal room conditions, formaldehyde tends to evaporate quickly and it has a pungent smell.  However, unlike other VOCs, it’s highly soluble in water (most VOCs have low water-solubility).  This means that as the water vapor in the air increases (humidity increases), formaldehyde vapor reacts with the water vapor to form methane diol, also called methylene glycol (hydrated formaldehyde, CH2(OH)2).  (Investigation of air–water exchange of formaldehyde using the water surface sampler: Flux enhancement due to chemical reaction)  Methanediol is listed as one of the main ingredients of "Brazilian blowout", a hair-straightening formula marketed in the United States. Although methanediol or methylene glycol is in equilibrium with formaldehyde (it can change back into formaldehyde by rejecting the water molecule), it’s not considered to be toxicologically equivalent to formaldehyde and experts conclude that “it has essentially no toxicity absent that attributable to formaldehyde present in equilibrium.”  Sporadic reports of sensory irritation occurring in conjunction with the use of hair smoothing products have been attributed solely to the presence of airborne formaldehyde gas emitted when these products are heated as part of the process. (Formaldehyde and methylene glycol equivalence: Critical assessment of chemical and toxicological aspects)  Therefore, if you’re going to be exposed to formaldehyde, it’s better that it’s the hydrated (methylene glycol) version, which is present in more humid air.  In this role, methane diol or methylene glycol likely serves as a biological “buffer” to detoxify formaldehyde by limiting its concentration in the body while having no inherent toxicity.

The good thing is that, as mentioned previously, you can actually control off-gassing of materials, by controlling the temperature and humidity.  In a 2019 study of the release of volatile organic compounds from dry building materials (artificial wood-based boards) under different temperatures and relative humidity, increase of ambient temperature and relative humidity promotes the release of TVOC (total VOCs), which affects its peak concentration and stable concentration, and the effect on formaldehyde release is more significant.

What does this mean?  Higher temperatures cause materials to release VOCs more quickly.  Higher humidity had an even greater effect.  Why is this?  

Basically, increasing temperature causes increased movement of formaldehyde molecules inside the wood-based board, promoting their release.  In addition, increased temperatures also change the pore structure characteristics of the board, causing a decrease in its adsorption capacity for formaldehyde.  Both of these factors accelerate the release of formaldehyde with increasing temperatures.

Increase of relative humidity is a bit more complex: it increases the water vapor pressure in the air.  Increased water vapor pressure in the air causes evaporation of water from the substrate (artificial board) to slow down.  Since water molecules occupy a relatively large portion of the pores of the board, they tend to push out VOC molecules into the air.  Another way to explain this is that as the relative humidity increases and the board absorbs moisture from the air, VOCs (including formaldehyde) are released into the air to make room for more water molecules.

Here are the conclusions of the study: 

1. The release process of formaldehyde from wood-based panels can be divided into three stages: initial rapid release phase, stable release phase, and long-term slow release phase. The release process of TVOC can be divided into an active period and a stable period in which the amount of release changes significantly with time.

2. Increasing the temperature or increasing the humidity, the release rate of formaldehyde and TVOC in the artificial board increased to different degrees. The change of temperature or humidity has a greater effect on the release of formaldehyde from the artificial board, and has less influence on the release of TVOC. Under the combined action of temperature and humidity, the effect of formaldehyde and TVOC release on wood-based panels is more intense.

Following are visual depictions of the release of formaldehyde and TVOCs with increasing temperatures, and with increasing humidity. (The effects of temperature and humidity on the VOC emission rate from dry building materials)  See how formaldehyde release really “ramps up” with increasing temperatures and humidity, much more so than the total VOCs? (18 degC ~ 64 degF, 23 degC ~ 73 degF, 28 degC ~ 82 degF). 

What does this mean for off-gassing of products in our homes?  If you want to keep it to a minimum, keep the temperature and humidity down.  Of course, products will still off-gas at a lower rate for a long time, but if you choose them wisely, it will be less likely to have serious health consequences.  Coating hard surfaces with AFM Safecoat products can also help to suppress off-gassing, and using an air purifier with a substantial amount of activated carbon can adsorb VOCs like formaldehyde (AirPura purifiers have a competitive amount of activated carbon and quiet fans according to this post).  Finally, ventilating with fresh air dilutes the offgas (however, beware that increasing ventilation on warm, humid days will also increase offgassing).  

Otherwise, if you do buy something that is extremely stinky with VOCs but can be moved, you can take it out of your home to a covered space where it can offgas safely.  Using fans, heaters and open windows, you can rapidly release the formaldehyde and other VOCs and get it to a lower, steady state of offgas that should be more tolerable when you bring it back into your cooler, drier home.  

Photo by Tiana Borcherding on Unsplash