VOC gases

So what is a VOC? – Download this ION Science guide.

Volatile organic compounds (VOCs) are a wide range of natural and synthetically occurring chemicals. They are found almost everywhere on earth and even in outer space!

They are described as volatile because they evaporate at temperatures found on Earth, releasing molecules into the atmosphere.

VOCs are also extremely useful for mankind. They form the building blocks of many synthetic materials (plastics, rubbers, glues, paints etc.), used to create pharmaceuticals and are a great fuel for transport and heating.

Whilst many VOCs have no adverse effects on health and the environment, some are harmful. Health effects include eye, nose and throat irritation from short term exposures (think about a whiff of super glue) and long-term exposure to very low concentrations you are not aware of (parts per billion) may cause damage to liver, kidneys, central nervous system and cancers.

As VOCs exist as a gas at room temperature the main exposure route is through normal respiration. Exposure to harmful VOCs can happen at home, outdoors or in the workplace.

Domestic and light industrial sources of VOC include building materials, furniture, carpets, heating and cooking systems, stored solvents and cleaning products. Generally, VOCs are released slowly from these sources and would not cause a problem. However, modern buildings have low air exchange rates (to reduce heating and air conditioning costs) therefore concentrations can easily rise to harmful levels. VOCs are now widely recognised as a major contributor to sick building syndrome compromising Indoor Air Quality (IAQ).

In medium and heavy industries, there are more sources of VOCs and higher concentrations can also exist. Here, VOCs pose additional threats. VOC vapours are heavier than air and may displace oxygen in confined spaces posing an asphyxiation risk to workers. VOCs also have relatively low lower explosive limits (LEL) than common gases. For example, methane, the major component of natural gas has a lower explosive limit of 4.4% by contrast VOCs commonly found in the work place have LELs of 1%.