Which statement describes the relationship of DAC to ALI?

Which statement describes the relationship of DAC to ALI?

• A. DAC is the air concentration corresponding to ALI breathed for 2,000 hours
• B. ALI is calculated independently of DAC
• C. DAC is a dose rate metric
• D. ALI is a surface contamination threshold

Answer: (A)

DAC is the air concentration in which, if a worker breathes it for about 2,000 hours in a year, the intake reaches the Annual Limit on Intake. In other words, ALI sets the maximum allowed inhaled activity per year, and DAC translates that limit into a concentration in air by using a typical breathing rate and exposure time. This connection comes from the inhalation equation: intake ≈ air concentration × breathing rate × time (with deposition factors as needed). So the statement that best describes their relationship is that DAC is the air concentration corresponding to ALI breathed for 2,000 hours. DAC is not a dose rate, ALI isn’t a surface contamination threshold, and ALI and DAC are intrinsically linked rather than calculated completely independently.

DAC is the air concentration in which, if a worker breathes it for about 2,000 hours in a year, the intake reaches the Annual Limit on Intake. In other words, ALI sets the maximum allowed inhaled activity per year, and DAC translates that limit into a concentration in air by using a typical breathing rate and exposure time. This connection comes from the inhalation equation: intake ≈ air concentration × breathing rate × time (with deposition factors as needed). So the statement that best describes their relationship is that DAC is the air concentration corresponding to ALI breathed for 2,000 hours. DAC is not a dose rate, ALI isn’t a surface contamination threshold, and ALI and DAC are intrinsically linked rather than calculated completely independently.