Definition of VOC

1. According to World Health organization (WHO)100 organic compounds used in the

indoor environment are classified according to their volatility by:

VOC = organic compound whose boiling point is in the range from (50°C to 100°C) to (240°C to 260°C)

VVOC= organic compound whose boiling point is in the range from < 0°C to (50°C to 100°C) SVOC= organic compound whose boiling point is in the range from (240°C to 260°C) to (380°C to 400°C)

2. According to a working group of the European Community (Report ECA 18) the definition of VOC is based on the retention time window in which a substance is eluted in

gas chromatography101:

VOC= all volatile organic compounds, in a capillary column coated with 100%

dimethylpolysiloxane, are eluted with a retention range between n-hexane (n-C6) and n-

hexadecane (n-C16). This corresponds to a boiling point range of 50-290°C.

VVOC= all compounds which, in a capillary column coated with 100% dimethylpolysiloxane, are eluted before n-hexane

SVOC= all semi-volatile organic compounds which, in a capillary column coated with 100% dimethylpolysiloxane, are eluted with a retention range between n-hexadecane and n-docosane

These definitions are also used in the AgBB scheme78

and in the international standard EN ISO

16000-6102.

VOC= organic compounds within the retention range of C6 to C16.

SVOC= organic compounds within the retention range from C16 up to C22.

Note: At the moment ISO 16000-6 is using contradictory VOC definitions: The definition

―50°C-100°C to 240°C-260°C‖ corresponds to an analytical interval from C6 to C14 (see

paragraph 3.2 of EN ISO 16000-6). At another place (see paragraph 11 from EN ISO 16000-6),

VOC is defined from C6 to C16. This corresponds to circa 70°C to 300°C.

3. According to 2004/42/EC77

:

VOC= any organic compound having an initial boiling point less than or equal to 250°C measured at a standard pressure of 101,3 kPa.

4. Wolkoff et al have proposed a new definition of organic compounds in indoor air (OCIA)

in the context of ―reactive chemistry‖103:

Chemically non-reactive (stable) organic compounds, e.g. octane, toluene and butanol Chemically “reactive” organic compounds with –C=C– bonds like styrene, limonene etc that react with ozone alone or with nitrogen dioxide in presence of light to produce new oxygenated products

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Organic compounds that form chemical bond(s) to receptor-sites in the mucous membranes i.e. biologically reactive (e.g. formaldehyde)

Organic compounds with (known) toxic properties, e.g. fungicides (e.g. PCP); these compounds are characterized by effects developed over long duration of exposure NOTE: MVOCs= microbial volatile organic compounds, a variety of VOCs produced by moulds

and bacteria104.

In ISO 16000-5105 a general description is given of the emission characteristics of VOC sources.

A generalized overview of the emission characteristics of building materials is depicted in Figure 6.

Emission characteristics and indoor air concentration

Example of source Example of emitting VOCs

Continuous

-active over a long period

-uniform, short term changes in emission rates are low

Concentration Time Building products -PVC -linoleum -cork

-parquets and wooden furniture

plasticizers, viscosity modifiers, solvent residues, antioxidants, stabilizers

linseed oil and oxidation products as process residues

binders, thermal degradation products wood extractives, solvent from varnishes, surface treatment oils and waxes

Continuous -irregular, decaying Concentration

Time

Paints, adhesives _{Organic solvents, coalescing solvents,} film forming reaction products, film degradation products‖

co-solvents, emulgators, defoamers, resins as colophony,

Figure 6: (generalized) Emission characteristics of VOC sources (building materials)105

A construction product in use can act as primary and secondary emission source for the emission of particles and/or VOCs to the indoor air:

Primary emission: The physical release of compounds which are present in a new product Secondary emission: Compounds produced by chemical reaction in the product or in the

indoor environment.

A schematic overview of the influence of the test conditions on primary and secondary emissions is given in Figure 7.

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Test Test (single product) (single product) Pri ma ry e mi ssi o n Pri ma ry a n d se co n d a ry e mi ssi o n climatic parameters humidity oxidants

Figure 7: Influence of test conditions on primary and secondary emission (substrate-adhesive-flooring material)106.

In Figure 8, the generation of primary and secondary emissions from building products is

described107. Three different cases can be distinguished:

1. An unwanted reaction is happening during the production of a material and the formed reaction product is released at the customers site.

2. An unwanted reaction is happening at the surface or in different materials at the customers site, e.g. between concrete, adhesive and flooring material (see Figure 7) 3. An unwanted reaction of primary compounds with other primary compounds or reactive

gases is happening in the gas phase at the customers site.

Figure 8: Formation of primary and secondary emissions from chemical constituents of (building) materials for indoor use107.

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5. Testmethods/standards/analysis methods for VOCs and PM

A proper implementation of Council Directive 89/106/EEC on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products (Construction Products Directive, CPD), requires common test concepts and measuring methods to close out threats to human health and the environment (in this case: indoor air) from construction works. The necessary concepts and methods should allow the functioning of the Internal Market for construction products and the compliance of construction works with the level of protection laid down in regulatory requirements of Member States and the EU. Hence the need for selection and adjustment or development (if needed) of appropriate testmethods for the determination of the emission of VOCs and particulate matter (PM) from construction products into indoor air. In this section an overview will be given of the available testmethods/standards & analysis methods in the field of VOC and PM emissions into indoor air.