The analysis of the levels of hazardous substances in the air inhaled by workers in the chemical industry and similar working environments is vital in monitoring adherence to statutory concentration limits and protecting the workers from the adverse effects of such substances. This volume contains 15 standardized methods for the determination of chemical compounds in the air of the work area. All methods are suitable for routine use. They meet exceptionally high standards of reliability and reproducibility. Considerable emphasis is placed on sample collection methods and on analytical quality control. A chapter 'Procedures for the preparation of calibration gas mixtures' provides general information on air monitoring methodology.