Definition(s)
Acceptable ceiling concentration (ACC)
The designated level of an air contaminant to which an employee may be exposed at any time during an 8-hour shift, except for a time period and up to a concentration not exceeding the “acceptable maximum peak above the acceptable ceiling concentration for an 8-hour shift.”
Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global Standards