Monitoring and Measuring Exposure
Air/Environmental Monitoring
When toxic chemicals are present in the workplace, exposure can be determined by measuring the concentration of a given chemical in the air and the duration of exposure. This measurement is called air or environmental monitoring or sampling and is usually done by industrial hygienists, using various types of instruments. Environmental monitoring is the most accurate way to determine exposure to most chemicals.
The air is collected from your breathing zone (the air around your nose and mouth) so that the concentrations measured will accurately reflect the concentration you are inhaling. The exposure levels calculated from this monitoring can then be compared to the Permissible Exposure Limit (PEL) for that chemical.
Biological Monitoring
For chemicals that are absorbed by routes other than inhalation, such as through the skin and by ingestion, air monitoring may underestimate the amount of chemical you absorb. For these and some other chemicals, the levels of the chemical (or its breakdown products) in the body can sometimes be measured in the blood, urine or exhaled air. Such testing is called biological monitoring, and the results may give an estimate of the actual dose absorbed into the body.
For one substance, lead, biological monitoring is required by law when air monitoring results are above a certain level. The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended the exposure limits for biological monitoring for a small number of chemicals. These are called Biological Exposure Indices (BEIs) and are published together with TLVs. (See glossary)
Knowledge Check Choose the best answer for the question.
3-10. Measurement of exposure to chemical exposure by sampling blood, urine or exhaled air is called _____.
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