Perfluorocarbons (PFCs) are fully fluorinated hydrocarbons that are used as blood plasma substitutes, in medical imaging and in the cosmetics industry. Most are inert and can also be used as tracers for applications such as air flow. However, because of their C-F bonds and their longevity in the atmosphere, PFCs have large global warming potentials and are a current concern in terms of climate change. At present, their levels in the atmosphere are very low (parts per quadrillion, 1 in 10[superscript 15]) but, once released, they are immortal on human timescales. Measuring such low levels is difficult and methodologies developed by the Atmospheric Chemistry Research Group at the University of Bristol are described. (Contains 3 figures and 1 table.)