Ever wondered why TPH (Total Petroleum Hydrocarbons) often are not a measure of all the hydrocarbons present in a petroleum hydrocarbon mixture? Did you know that in 2005 the Environment Agency proposed a slightly different carbon banding for human health risk assessment (HHRA) to the TPHCWG (Total Petroleum Hydrocarbons Criteria Working Group) one? If so this document is for you. It is relatively short but packed full of useful information from rules of thumb, to worked examples of calculations; useful tables including mobility ranking of petroleum hydrocarbon fractions and substances of concern in common petroleum hydrocarbon mixtures as well as links to key reference documents and other guidance. It should be noted that it has been published as a supplementary report to the Environment Agency’s Remedial Targets Methodology: Hydrogeological Risk Assessment for Land Contamination (2006) and should be used alongside this and other pertinent EA advice and guidance. This supplementary report is free to download from the CL:AIRE website at http://www.claire.co.uk/phg.