Distribution and skewness of occupational exposure sets of measurements in the Norwegian industry

Abstract

Aggregated occupational sets of exposure measurements from the Norwegian industry registered in the exposure database EXPO at The National Institute of Occupational Health, Oslo were examined with respect to distributions and skewness. Data for lead in blood show a truncated almost normal distribution because of regulations for workers with high lead in blood concentrations. The styrene, dichloromethane and acetone measurements show quasi log-normal distributions possibly because of over-representation of worst-case measurements. The other personal and stationary measurements are relatively good fitted to a log-normal model. The stationary measurements indicate generally lower mean levels than the corresponding personal measurements. The statistical parameter skewness is valuable in connection with an exposure database as a distribution test for raw data and log-transformed data.