What is the maximum CO reading considered safe for a fit-testing atmosphere?

What is the maximum CO reading considered safe for a fit-testing atmosphere?

• A. Less than 20 ppm
• B. Less than 35 ppm
• C. Less than 50 ppm
• D. Less than 100 ppm

Answer: (B)

During a CO-based fit test, the air in the testing area must stay at a level of carbon monoxide that is safe for the brief exposure and still meaningful for the test readings. The standard safe upper limit used for this context is less than 35 parts per million. This level protects the person from CO-related health effects during the short duration of the test while still allowing the tracer gas to be present in measurable amounts for detecting leaks. Exceeding this concentration could cause symptoms like headaches or dizziness that would interfere with the test and potentially skew results. While a lower figure, such as 20 ppm, would be even safer, 35 ppm is the commonly accepted threshold for keeping the testing environment both safe and practical.

During a CO-based fit test, the air in the testing area must stay at a level of carbon monoxide that is safe for the brief exposure and still meaningful for the test readings. The standard safe upper limit used for this context is less than 35 parts per million. This level protects the person from CO-related health effects during the short duration of the test while still allowing the tracer gas to be present in measurable amounts for detecting leaks. Exceeding this concentration could cause symptoms like headaches or dizziness that would interfere with the test and potentially skew results. While a lower figure, such as 20 ppm, would be even safer, 35 ppm is the commonly accepted threshold for keeping the testing environment both safe and practical.