Its origin may be natural or generated by man, for example in the emission of organic solvents, vehicle circulation or combustion of fuels.
The Spanish state classifies them in three groups ordered according to their potential danger:
- Compounds extremely dangerous for health, such as benzene
- Class A compounds, which can cause significant damage to the environment, such as aldehydes.
- Class B compounds, with less impact on the environment, such as acetone.
However, among class A there are also compounds classified as carcinogens by the World Health Organization (WHO) like formaldehyde.
A common feature of VOCs is that they react with nitrogen oxides (emitted by diesel vehicles) and sunlight. This reaction generates ozone at ground level, which causes negative effects on health, especially respiratory harm.
Other effects of VOC are respiratory problems, throat and eyes irritation, dizziness, irritability, difficulty in concentrating. In the long term, they can cause more serious damage, for instance, in the central nervous system or the liver. Some of them have a carcinogenic effect such as benzene.
The United States Environmental Protection Agency (EPA) determines that the concentration of volatile organic compounds indoors can be up to 5 times higher than outdoors.