Question

Based on the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values, permissible exposure limits for chemicals have been developed. These PELs are broken into three categories: ceiling limits which are not to be exceeded even instantaneously, Short Term Exposure Limits which are based on a 15 minute exposure, and ________?

1) Long Term Exposure Limits which are based on an 8 hour time-weighted average
2) Medium Term Exposure Limits which are based on a 1 hour exposure
3) Permanent Exposure Limits which are based on a lifetime exposure
4) Temporary Exposure Limits which are based on a 30 minute exposure

Answer 1

Long Term Exposure Limits are based on an 8-hour time-weighted average. These limits are pivotal for maintaining safety over regular, extended periods of work. Therefore, correct option is 1.

Step-by-step explanation:

Based on the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values, permissible exposure limits (PELs) for chemicals are classified into different categories to help underscore the importance of limiting exposure in industrial and environmental settings.

These categories include ceiling limits, which must not be passed even for a moment, Short Term Exposure Limits (STELs) based on a 15-minute exposure, and the option in question, which is Time-Weighted Average (TWA) Limits, based on an 8-hour exposure.

The correct answer to the question is (1) Long Term Exposure Limits which are based on an 8-hour time-weighted average. Long-term exposure limits are critical for ensuring worker safety and health over an extended period, in contrast to the instantaneous nature of ceiling limits or the brief duration assessed by STELs.