Statistical methods for establishing equivalency of a sampling device to the OSHA standard

Occupational Safety and Health Administration (OSHA) regulations allow the use of an alternative sampling device for exposure monitoring provided the device has been demonstrated to be equivalent to the standard device. For example, the OSHA standard allows the use of an alternate cotton dust sampler that is equivalent to the Lumsden-Lynch vertical elutriator (VE); also, OSHA defines the accuracy of the monitoring device for measuring airborne chemicals such as benzene and sulfur dioxide. Typically, the OSHA criterion is that 90% of the readings of the sampling device should be within +/- 25% of the readings obtained by the standard device or within +/- 25% of the actual airborne chemical concentration. This article proposes two statistical tests for establishing that an alternative measuring device of airborne chemicals or dust is equivalent to the OSHA standard. The statistical tests are illustrated using an example.