Atmosphere

Air toxics and indoor air quality in Australia

State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4

Part C: Factsheets (continued)

Total volatile organic compounds (total VOCs)

Substance name: Total volatile organic compounds (total VOCs)
CASR number: Not applicable
Molecular formula: Not applicable
Synonyms: Volatile organic compounds (VOCs), non methane volatile organic compounds (NMVOCs)

Physical and chemical properties

The World Health Organization definition of VOCs includes all organic compounds (substances made up of predominantly carbon and hydrogen) with boiling temperatures in the range of 50-260°C, excluding pesticides. This means that they are likely to be present as a vapour or gas in normal ambient temperatures. Substances that are included in the VOC category include aliphatic hydrocarbons (such as hexane), aromatic hydrocarbons (such as benzene, toluene and the xylenes), and oxygenated compounds (such as acetone and similar ketones).

Chemical properties vary widely.

Common uses

'Total VOCs' are not a category of substances but a grouping of a wide range of organic chemical compounds to simplify reporting when these are present in ambient air or emissions. Many substances (eg natural gas) could strictly be classified as VOCs, but the term is reserved to characterise the presence of substances in polluted air (ie the term generally refers to the vapours or gases given off by the compounds rather than the liquid phase of the compounds).

Sources of emissions

Point sources

VOCs are released from a wide range of industrial processes. Processes involving solvents, paints or the use of chemicals are likely to be the most significant sources. The major point sources of VOCs in Australian cities are petrol refining and fuel storage, and manufacturing industry.

Diffuse sources, and point sources included in aggregated emissions data VOCs are released from painted surfaces, fabrics, carpets, printed paper and material and fibreboard products. Petrol stations are significant emitters of VOCs.

Natural sources

There are significant nonanthropogenic sources of VOCs, since most Australian State capitals are adjacent to areas of bush, which emit volatile oils. In the Brisbane area, for instance, such sources contribute (and are expected to continue to contribute) 60% of the observed VOCs.

Mobile sources

VOCs are emitted in vehicle exhausts and from fuel tanks.

Consumer products that may contain total VOCs

VOCs are emitted from some fabrics, carpets, fibreboard, plastic products, glues and solvents, some spray packs and some printed material, paints, varnishes, wax, cleaning products, disinfectants, cosmetic, degreasing products, hobby products, fuels. The rate of emission may decrease over time as the volatile components are depleted.

Health effects

How might I be exposed to total VOCs?

People are exposed by breathing contaminated air. VOCs may build up in indoor environments because there are more sources and lower rates of ventilation. Indoor air is more likely to contain higher concentrations of VOC than outdoor air.

By what pathways might total VOCs enter my body?

VOCs are present in gas or vapour, so they enter the body by inhalation.

Health guidelines

There are no national guidelines.

What effect might total VOCs have on my health?

The health effects depend on the specific composition of the VOCs present, the concentration and the length of exposure. High concentrations of some compounds that may occur when working with materials or processes that emit VOCs could have serious health effects. These should be considered under the effects of the specific component. General effects of lower concentrations include eye, nose and throat irritation; headaches; loss of coordination; nausea; and damage to the liver, kidneys and central nervous system. Some VOCs can cause cancer in animals; some are suspected or known to cause cancer in humans. Build-ups of VOCs in indoor environments have been associated with 'sick building syndrome'.

Environmental effects

Environmental fate

VOCs include an enormous range of substances; the specific fate in the environment varies. In general VOCs are degraded by sunlight, so eventually break down to simpler compounds. VOCs are necessary for the formation of smog, reacting with oxides of nitrogen to produce ozone and other compounds.

Environmental transport

VOCs are transported in air. The term 'VOCs' generally refers only to the various compounds in vapour or gas form, so water and soil transport are not relevant.

Environmental guidelines

There are no national guidelines.

What effect might total VOCs have on the environment?

VOCs are environmentally significant mainly because of their role in the formation of photochemical smog. Other environmental effects depend on the composition of the VOCs, the concentration and the length of exposure. Some VOCs can have serious effects on animals and plants. Secondary effects may also occur (eg due to the impact of smog). In liquid form and solutions, VOCs can affect water and soil.

Key

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