A procedure has been devised that permits benzene exposure data to be compared with the three ANSI exposure limits—peak, ceiling, and time-weighted average concentrations. For most industrial operations, the vapor concentrations closely follow a log-normal distribution. Accordingly, the sampling data are plotted on log-normal probability paper using Larsen's convention. A line of limiting exposure is constructed on the same plot, and a visual comparison is made for compliance. Plotting values for the limiting line of acceptable exposures are given for sampling periods of 10 to 240 minutes. A numerical example that illustrates the evaluation procedure is also included.