A new method called the FTIR tracer Method (FTM) has been developed for mesuring and quantifying fugitive (diffuse) emissions of hydrocarbons. The method has been evaluated in field experiments whch were conducted in the vicinity of several petrochemical plants and an oil refinery during 1993-1995. The technique is based on concentration measurements with infrared remote sensing by Long Path Fourier Transform InfraRed (LPFTIR), combined with tracer releases. The field experiements show the FTM to be very useful for mass flux measurements of both alkanes and alkenes and that the measurements are consistent with the conventional SF6 method. However, the technique needs to be further validated and a more thorough understanding of the measurement uncertainties have to be achieved.