Objectives As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminium manufacturing, area particle samples were collected in smelters and fabrication facilities to assess instrument reliability and particle size distribution at different process areas.

Method Personal Modular Impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used to collect samples. The coefficient of variation (CV) of collocated samples of the same type was used to evaluate the reproducibility of the impactors. PM_2.5 measured by PMI was compared to PM_2.5 calculated from MiniMOUDI data to assess the validity of using PMI to measure fine particles in personal sampling. Mass median aerodynamic diameter (MMAD) was calculated to characterise particle size distribution at different locations.

Results 62 MiniMOUDI and 71 PMI samples were collected at 44 production areas. Most of CVs were less than 30%. The slope of the liner regression of PMI_PM_2.5 versus MiniMOUDI_PM_2.5 was 1.12 mg/m³ per mg/m³ (± 0.05), with correlation coefficient of 0.97 (± 0.01). MMADs in fabrications were significantly smaller and less variable than those in smelters (p = 0.001). The fraction of PM₁₀ which was PM_1.0 or PM_0.56 was significantly higher in fabrications than in smelters (p < 0.001).

Conclusions The reproducibility for impactors was moderate to high. PM_2.5 measured by PMI can be a valid measure for fine particle exposure in personal sampling. The concentrations of submicron and quasi-ultrafine particles were similar in fabrications and smelters. PM_2.5 is not a good surrogate for ultrafine particles in this setting.