Final answer:
The allowable limit for an air contaminant without adverse effects is known as the Threshold Limit Value (TLV), with similar exposure limits including STEL, Ceiling Limit, and TWA. The EPA sets standards such as National Ambient Air Quality Standards and Maximum Contaminant Levels to safeguard health and the environment.
Step-by-step explanation:
The allowable limit for an air contaminant that a worker can be exposed to without adverse effects is known as the Threshold Limit Value (TLV). The TLV represents the level at which it is believed a worker can be exposed day after day for a working lifetime without adverse health effects. Similar guidelines include the Short-Term Exposure Limit (STEL), which is a period not exceeding 15 minutes of exposure that should not be repeated more than four times per day with at least 60 minutes between exposures. There is also the Ceiling Limit, which is an exposure limit that should not be exceeded at any time. Lastly, the Time-Weighted Average (TWA) is the average exposure based on a standard 8-hour workday or a 40-hour workweek. It's important to note that the Environmental Protection Agency (EPA) sets various standards including the National Ambient Air Quality Standards for principal air pollutants, and Maximum Contaminant Levels (MCLs) for drinking water, to protect public health and the environment.