Volatile organic compounds, or VOCs, are gases that are emitted into the air from products or processes. Some are harmful by themselves, including some that cause cancer. In addition, they can react with other gases and form other air pollutants after they are in the air.Breathing VOCs can irritate the eyes, nose and throat, can cause difficulty breathing and nausea, and can damage the central nervous system as well as other organs. Some VOCs can cause cancer. Not all VOCs have all these health effects, though many have several. Outdoors, VOCs can cause similar health effects, but also can react with nitrogen oxides to produce ozone pollution, the nation’s most widespread outdoor air pollutant.