Abstract
An industrial hygiene pilot study was conducted to estimate the concentrations of respirable dust likely to be encountered during the personal sampling phase of a large-scale morbidity study of the portland cement industry. An analysis of the pilot study data showed little variability in exposure for subjects working in the same job in the same area of the same plant. Thus, one could estimate mean exposure by sampling several subjects rather than sampling the same subject several times. It was concluded that for statistical considerations, the best approach would be to sample four jobs per area and six subjects per job. Practical considerations required one more often to select six jobs with two subjects per job, however. Overall, the collection of fewer samples was required during the morbidity study than was anticipated originally. In turn, the reduction in the number of samples to be collected resulted in a savings of time and resources.