An extensive survey is given of the methods and instrumentation for the determination of benzene (71432) vapor in air at concentrations relevant from an occupational health standpoint. Considerations include the problems of benzene toxicity, measurement and control; descriptions and evaluation of methods and instrumentation, including short term, continuous, remote and long-term sampling; chemical methods, including gas detector tubes and gas chromatography; calibration, readout and control. Nonspecific instruments include catalytic combustion detectors, flame ionization detectors, flame thermal detector, selective catalytic combustion detectors, gas density detector, thermal conductivity detectors, and alpha ionization. Semispecific instruments include ultraviolet photometers, infrared monitors, and flame emission photometers. Specific instruments include ultraviolet spectrophotometers, infrared spectrophotometry, polargraphy and mass spectrometry. Potential new methods and instrumentation include gas chromatography improvements, optical methods, chemical substrative methods, the plasma chromatograph, polargraphic methods, coulometry, and calibration improvements. Appendices include lists of manufacturers and manufacturer's data sheets and brochures.