Under Habels Rule, which expression correctly represents exposure?

Under Habels Rule, which expression correctly represents exposure?

• A. Concentration PPM divided by minutes
• B. Concentration PPM multiplied by minutes
• C. Concentration PPM minus minutes
• D. Concentration PPM added to minutes

Answer: (B)

Exposure is the amount of contaminant a person encounters over a period, which is found by multiplying how concentrated the contaminant is by how long you’re exposed. Under Habels Rule, this gives a measure in ppm·minutes. So you represent exposure as concentration in ppm multiplied by minutes. If you divide by minutes, you’d misrepresent how exposure builds with time, and adding or subtracting minutes wouldn’t reflect the actual cumulative dose. For example, 5 ppm for 20 minutes equals 100 ppm·minutes of exposure.

Exposure is the amount of contaminant a person encounters over a period, which is found by multiplying how concentrated the contaminant is by how long you’re exposed. Under Habels Rule, this gives a measure in ppm·minutes. So you represent exposure as concentration in ppm multiplied by minutes. If you divide by minutes, you’d misrepresent how exposure builds with time, and adding or subtracting minutes wouldn’t reflect the actual cumulative dose. For example, 5 ppm for 20 minutes equals 100 ppm·minutes of exposure.