#Breathing zone monitor portable#
Sampling and analysis may also be performed by portable direct reading instruments, real-time continuous monitoring systems, passive dosimeters or other suitable methods. The sampling and analysis may be performed by collection of the benzene vaptor or charcoal absorption tubes, with subsequent chemical analysis by gas chromatography. There are a number of methods available for monitoring employee exposures to benzene. Sampling and analysis must be performed with procedures meeting the requirements of the standard. Air samples should be taken in the employee's breathing zone (air that would most nearly represent that inhaled by the employee). The arithmetic average of all such random samples taken on one work shift is an estimate of an employee's average level of exposure for that work shift.
Random sampling means that any portion of the work shift has the same change of being sampled as any other. Short-time interval samples (or grab samples) may also be used to determine average exposure level if a minimum of five measurements are taken in a random manner over the 8-hour work shift. Measurements taken for the purpose of determining employee exposure to benzene are best taken so that the representative average 8-hour exposure may be determined from a single 8-hour sample or two (2) 4-hour samples. Appendix D to § 1910.1028 - Sampling and Analytical Methods for Benzene Monitoring and Measurement Procedures
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