(1) No person shall cause or contribute to concentrations of hydrogen sulfide in the ambient air which exceed the following standard:

(a) hourly average: 0.05 ppm, one-hour average, not to be exceeded more than once per year.

(2) Measurement method: For determining compliance with this rule, hydrogen sulfide shall be measured by the methylene blue spectrophotometric method, as more fully described in "Methods of Air Sampling and Analysis, Second Edition" (1977) Method P and CAM 126-6, or by an approved equivalent method.