Low-VOC Paint: Choosing Healthier Interior Finishes

The Pretty Good House Blog

Low-VOC labels are a good starting point, but they’re only part of the story

We talk a lot about indoor air quality (IAQ) in our book, especially in the chapters on materials (a pollutant “source”) and on mechanicals (the pollutant “dilution”). Many of the compounds we worry about are classified as volatile organic compounds (VOCs), a term we all are familiar with even though we may not know precisely what it means.

What makes a VOC volatile?

As the name implies, VOCs are unstable chemicals that easily become airborne. The precise moment when we call them “volatile” is a regulatory rather than a scientific distinction, and various regulatory bodies at various state and national levels have different thresholds. They all, though, focus on compounds with high vapor pressure at room temperature, meaning they will evaporate from a liquid or solid state into airborne gas. From there, they can react with other compounds to form things like ground-level ozone (smog), or they can directly damage health through breathing, eating, or absorption through the skin.

Plenty of VOCs are naturally occurring—certain plant and tree odors (e.g., an orange peel) are obvious examples. They can still be indoor-air pollutants. Our co-author Chris Briley discovered during design for a client with multiple chemical sensitivity (MCS) that she reacted strongly to the terpenes in the raw pine. “That nice pine smell we all love was a terrible irritant for her,” he says.

The effect of exposure to even dangerous ones can vary, but repeated and prolonged exposure increases the risk significantly. Sensitivity often increases with exposure. As a rule, VOCs are significant contributors to indoor air pollution and should be avoided.

Why paint matters for indoor air quality

There are plenty of things in a house that can emit VOCs: furniture, carpeting, cleaning products—anything that has a strong smell. But if you think about square footage, one…