What type of exposure limit indicates the maximum duration a worker can be exposed to a substance without respiratory protection?

The correct answer, Threshold Limit Value, refers to the maximum concentration of a hazardous substance to which a worker can be exposed continuously for a typical workday and over a working lifetime, without experiencing adverse effects. This value is primarily set based on the assumption that if the exposure stays below this threshold, the risk of harm is minimal.

In contrast, other terms used in workplace exposure limits serve different purposes. The Time Weighted Average accounts for the average exposure over a standard workday, typically reflecting longer-term exposure risks rather than immediate safety scenarios. The Permissible Exposure Limit, often associated with regulatory standards, specifies limits that are legally enforceable but may not directly indicate the necessity for respiratory protection. The Short Term Exposure Limit is designed to protect workers from exposure to high concentrations of hazardous substances over a shorter period, usually 15 minutes, and does not convey the same long-term exposure context as the Threshold Limit Value.