What is the maximum benzene exposure limit in ppm?

• A. 5 ppm
• B. 2 ppm
• C. 0.5 ppm
• D. 1 ppm

Answer: (D)

Understanding exposure limits over time helps here. Benzene is a carcinogen, so regulations set how concentrated the air can be for workers on a shift. The standard permissible exposure limit for benzene is 1 ppm as an eight-hour time-weighted average, meaning the average concentration over a full work shift should not exceed 1 ppm. There is also a short-term exposure limit of 5 ppm for brief periods (about 15 minutes), but that is not the limit for a whole shift—it's a temporary ceiling. The other options (5 ppm, 2 ppm, 0.5 ppm) either reflect the short-term limit or are not the standard long-term PEL values. So the maximum permissible long-term exposure is 1 ppm.