Expanded Polystyrene EPS is manufactured from styrene which is a monomer that has been manufactured on an industrial scale for more than 60 years. It is used in the manufacture of a wide variety of plastics and rubber products.
Styrene occurs naturally and can be found in many foods including strawberries, beans, nuts, beer, wine, coffee beans and cinnamon.

During the manufacturing process of EPS a non CFC blowing agent called pentane is used to expand the polystyrene granules into its familiar expanded form.
Pentane is a volatile liquid which is formed by natural processes such as the anaerobic decomposition of plant matter by micro organisms and by the digestive systems of animals. It belongs to the same family as butane, methane etc. which are commonly used as heating fuels.

During the manufacturing process any pentane released is quickly converted in the atmosphere via a photochemical reaction into carbon and water. As it does not contain chlorine, pentane does not damage the ozone layer, unlike CFC (chlorofluorocarbons) and HCFC (hydro chlorofluorocarbons). However the pentane gas emitted during the manufacturing process does contribute to man made emissions of volatile organic compounds, in the region of 0.2%. To put this into perspective, a far larger quantity is released by the decomposition of household waste.
The amount of CO2 gas emitted during the manufacturing process is insignificant. In the case of Sips Industries Panels the CO2 emitted in the EPS manufacture is offset in around one week by the reduced energy requirements of the building.
Pentane as a gas is not regarded as a hazard to health.

Expanded polystyrene is non-toxic and inert. Expanded polystyrene consists of up to 98% air.

Expanded polystyrene boards can be recycled and ground into packing cases etc. Processes are being researched which will allow EPS to be recycled back into its original chemical form helping to reduce consumption of natural resources, however this has not been achieved to date.