Part 1: What are VOCs?
Virtually everyone has heard the term volatile organic compound, or VOC, but how many know what the term really means?
Most people think of VOCs as simply being toxic air pollutants, whether indoors or outdoors, and think of all VOCs as being the same. But this oversimplification hides the much more complex reality.
In layman’s terms, a VOC is a compound that contains carbon and is capable of being in the vapor phase.1 There is no such thing as VOC-free air anywhere on Earth. Many thousands of different VOCs are generated every day by Earth’s plants and animals, including microorganisms, and some also are emitted by the ground (such as methane). Virtually all of what we smell are due to VOCs. At the same time, many VOCs have no odor, or are present in the air at levels well below our ability to smell them.
Human activity can also produce VOCs, such as cooking foods, burning fuels, and using solvents. But these man-made VOCs make only a relatively small contribution to Earth’s VOCs. It has been estimated by scientists that eight times more carbon is emitted per year by natural VOC sources, compared to carbon from man-made VOC sources.2
There are many thousands of different VOCs, and no two are exactly alike.
Which is better? There is no correlation between a VOC being natural or man-made and its contribution to indoor or outdoor air quality. So while some specific VOCs can raise concerns related to indoor air and some other VOCs can contribute to ozone pollution, it is important to understand that all VOCs are not alike, and each has its own unique ability—and many none at all—to contribute to air quality problems indoors or outdoors.