VOCs are a group of carbon-based chemicals that easily evaporate at room temperature. Many common household materials and products, such as paints and cleaning products, give off VOCs. Common VOCs include acetone, benzene, ethylene glycol, formaldehyde, methylene chloride, perchloroethylene, toluene and xylene. Different VOCs have different health effects, and range from those that are highly toxic to those with no known health effect. Breathing low levels of VOCs for long periods of time may increase some people’s risk of health problems. Several studies suggest that exposure to VOCs may make symptoms worse in people who have asthma or are particularly sensitive to chemicals. VOCs particularly affect indoor air quality—concentrations of many VOCs are consistently higher indoors (up to 10 times higher) than outdoors.3 Some VOCs are known to be air toxics (see Air toxics).
Sources of human-made VOCs in 2013–14 have changed little since 2009–10. Figure ATM37 shows the proportions of VOC emissions from motor vehicles, burning, industry, and commercial and domestic sources.