What does a TLV/TWA take into account for its measurement?

A TLV (Threshold Limit Value) and TWA (Time-Weighted Average) specifically focus on the average concentration of a substance that a worker can be exposed to over a longer duration without adverse health effects. This measurement is crucial for occupational safety as it helps establish acceptable exposure levels over an 8-hour workday or a 40-hour workweek, taking into account the potential cumulative effects of prolonged exposure to hazardous substances.

In practice, the TWA ensures that during an extended exposure period, the average concentration remains below a set threshold, providing a systematic approach to managing and mitigating health risks in the workplace. This is why option C accurately reflects the function of a TLV/TWA, emphasizing long-term exposure limits rather than short-term spikes or maximum allowable concentrations.