Defining Volatile Organic Compounds
According to the State of the Environment Australia 2016 website, Volatile Organic Compounds (VOCs) are a group of carbon-based chemicals that easily evaporate at room temperature. Many common household materials and products, such as paints, glues, and cleaning products, give off VOCs.
Common VOCs include:
- Ethylene Glycol
- Methylene Chloride
The United States Environment Protection Agency website further asserts that Organic chemical compounds are everywhere in both indoor and outdoor environments as they have become essential ingredients in many products and materials. Indoor VOCs are mostly released into the air from the use of products and materials containing VOCs.
The US EPA provides what we have researched to be a very clear and understandable definition:
Volatile organic compounds (VOC) means any compound of carbon, (excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate) that participates in atmospheric photochemical reactions, except those designated by EPA as having negligible photochemical reactivity.
Volatile organic compounds or VOCs are organic chemical compounds whose composition makes it possible for them to evaporate under normal indoor atmospheric conditions of temperature and pressure. This general definition of VOCs is used in scientific literature and is consistent with the definition used for indoor air quality.
Since the volatility of a compound is generally higher the lower its boiling point temperature, the volatility of organic compounds is sometimes defined and classified by their boiling points. For example, the European Union uses the boiling point, rather than its volatility in its definition of VOCs.
A VOC is any organic compound having an initial boiling point less than or equal to 250° C measured at a standard atmospheric pressure of 101.3 kPa.5, 6, 7
VOCs are sometimes categorized by the ease they will be emitted. For example, the World Health Organization (WHO) categorizes indoor organic pollutants as:
Very volatile organic compounds (VVOCs)
Volatile organic compounds (VOCs)
Semi-volatile organic compounds (SVOCs)
The higher the volatility (lower the boiling point), the more likely the compound will be emitted from a product or surface into the air. Very volatile organic compounds are so volatile that they are difficult to measure. They are found almost entirely as gases in the air rather than in materials or on surfaces. The least volatile compounds found in air constitute a far smaller fraction of the total present indoors. The majority will be in solids or liquids that contain them or on surfaces including dust, furnishings, and building materials.