What Exactly Are Volatile Organic Compounds (VOCs)?

It’s always best to get super-technical first, I find, so let’s start with a nice, jargon-heavy definition:

A volatile organic compound is any organic compound with a high vapour pressure at room temperature and low solubility in water.

We should break this down into a few parts. Firstly, the term “organic compound” names any molecule partially or wholly composed of carbon-carbon bonds or bonds between carbon and other elements. Some of the most important substances in the world today are organic compounds, substances like oil, plastic and coal. You’ll even find organic compounds in items as ubiquitous as printers, cleaning fluids and permanent markers. In fact, all of these items contain volatile organic compounds, specifically, which, returning to our definition, tells us a little about why VOCs are such a concern for safety regulators and health officers.

You see, if a substance has a high vapour pressure at a particular temperature, this indicates that the substance is evaporating significantly. Vapour pressure is an odd measure, referring as it does to the amount of pressure imposed upon a liquid within a closed system by those particles which have passed from a liquid into a gaseous state. But by comparing the different vapour pressures of a substance at different temperatures, you’ll be able to get a good sense of the rate at which a substance evaporates, so vapour pressure is often used as an indicator of this rate. A volatile substance, then, is a substance which evaporates significantly at room temperature, making it a potential hazard – that's why, as Envirotech Online recently reported, certain workplaces should be more aware of VOCs and the risks they pose to the health of employees. 

The final property of volatile organic compounds identified in our definition is probably the most straight-forward, as most people already understand solubility. But, to refresh everyone’s memories, solubility is a substance’s capacity to dissolve – or, in technical terms, loosen its bonds – in particular liquids. In a way, it’s like evaporation, but instead of a liquid becoming a gas, it’s a solid becoming a liquid.

So, that’s a quick run-down on volatile organic compounds - that wasn’t too painful, was it? It’s hard to over-state just how prevalent VOCs are, especially in the modern workplace, so a little understanding will go a long way. Further, when it comes to air pollution, tackling the emission of volatile organic compounds is one of the highest priorities. If you’re interested to find out how much of a threat VOCs pose to health, take a look at our article on the topic.