Advances in Hair Styling 428 a green house gas in the upper atmosphere relative to carbon dioxide. Contributing factors include infrared absorption, spectral wavelengths, and product atmospheric lifetime. Global warming and the reduction of greenhouse gases have been the focus of the United Nations Framework Convention on Climate Change since 1992. This initiative is more formally recognized as the Kyoto Protocol which established target emissions in 1997 17 as of 2010 not all nations have ratified this treaty. The identified gases are carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulphur hexafluoride. Currently there are no regulations in the United States limiting GWP gases in hair care products, though there is some activity in the European Union. Aside from the determination of product form, the target region and/or regions and their respective regulatory environment is a primary factor in hair spray product development. Solvent, propellant, component, and polymeric choices will need to be made in concert to achieve a compatible and functional system. Understanding what ingredients are considered VOCs or have GWP implications, their interactions, compatibilities, and impact on product performance is necessary. The current definition of a VOC according to the EPA states “any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions.”18 Common ingredients used in hair styling products that are excluded as VOCs due to their negligible photoreactivity in the lower atmosphere are acetone, methyl acetate, cyclopentasiloxane, and hydrofluorocarbon 152a. Both acetone and methyl acetate have an inherent malodor which can be potentially covered by a fragrance however, each has additional concerns such as a Schiff base reaction in the presence of amines and hydrolysis in aqueous media, respectively. Cyclopentasiloxane is often used at high concentrations in shine sprays (55% VOC), thus eliminating the need for the addition of water, and is used at low levels in finishing