According to NIOSH regulations, the highest concentration of volatile anesthetic contamination allowed in the OR atmosphere when administered with N2O is which of the following?

According to NIOSH regulations, the highest concentration of volatile anesthetic contamination allowed in the OR atmosphere when administered with N2O is which of the following?

• A. 0.5 ppm
• B. 2 ppm
• C. 5 ppm
• D. 25 ppm

Answer: (A)

The question tests how NIOSH sets exposure limits for waste anesthetic gases in the OR. For volatile anesthetic agents, NIOSH defines an exposure limit of 0.5 parts per million (ppm) as an 8-hour TWA. Nitrous oxide has its own limit, 25 ppm (8-hour TWA). When both are present, exposures are evaluated with an additive approach: (volatile concentration divided by 0.5) plus (N2O concentration divided by 25) must be ≤ 1. This means the volatile anesthetic component cannot exceed its own 0.5 ppm limit, because any higher value would push the sum over 1 unless the N2O concentration is reduced correspondingly, which is not the scenario posed by the question. Therefore, the highest permissible concentration of volatile anesthetic contamination in the OR, when administered with N2O, is 0.5 ppm.

The question tests how NIOSH sets exposure limits for waste anesthetic gases in the OR. For volatile anesthetic agents, NIOSH defines an exposure limit of 0.5 parts per million (ppm) as an 8-hour TWA. Nitrous oxide has its own limit, 25 ppm (8-hour TWA). When both are present, exposures are evaluated with an additive approach: (volatile concentration divided by 0.5) plus (N2O concentration divided by 25) must be ≤ 1. This means the volatile anesthetic component cannot exceed its own 0.5 ppm limit, because any higher value would push the sum over 1 unless the N2O concentration is reduced correspondingly, which is not the scenario posed by the question. Therefore, the highest permissible concentration of volatile anesthetic contamination in the OR, when administered with N2O, is 0.5 ppm.