The 8-hour time-weighted average limit set by the Occupational Safety and Health Administration (OSHA) for carbon monoxide (CO) is 50 ppm. The OSHA regulation at 29 C.F.R. §1910.1000(d) requires employers to determine the cumulative exposure of workers to certain gases over an 8-hour work shift using the formula below.
Formula to determine cumulative exposure of workers to certain gases
Where:
E = equivalent exposure for the work shift
C = concentration during any period of time in which the concentration remains constant
T = duration of time in hours of the exposure
The regulation further stipulates that no employee can be further exposed to the gas when the value of E exceeds the 8-hour time-weighted average limit set for the given substance. Using the formula above, determine if the employer complied with this regulation if a worker is exposed to CO concentrations throughout the workday as follows: 45 ppm for 3.25 hours; 75 ppm for 2.5 hours; 50 ppm for 1.5 hours and 60 ppm for 45 minutes. Explain CO poisoning and the interaction of CO with hemoglobin.
