This paper describes a study that was carried out at a North American nickel alloy production facility to compare the levels of personal exposures to inhalable and total nickel-containing aerosols. It is part of a large body of work aimed at assessing the impact of introducing new personal sampling instrumentation with performance consistent with the latest criteria proposed by the International Standards Organization (ISO), the Comité Européen Normalisation (CEN) and the American Conference of Governmental Industrial Hygienists (ACGIH). Side-by-side sampling using the 37-mm filter holder (for total aerosol) and the so-called IOM inhalable aerosol sampler was conducted for the personal exposures of workers in a range of workplaces throughout the facility. The results showed that inhalable aerosol exposure levels-for both overall aerosol and for total nickel-were consistently and significantly higher than the corresponding total aerosol levels. Weighted least-squares linear regression yielded factors ranging from about 1.3 to 2.4 for overall dust and from about 1.5 to 3.5 for nickel. Inspection of the statistical distribution of the exposures for the whole plant suggested that it was log-normal.