Comparison of virtual impactor and two-filter particle samplers.

The two-filter method for samplng of inhalable particles in air has been compared with the virtual impactor method (Dichotomous virtual impactor), which is considered a reference method. The two-filter method correlated well with the virtual impactor method, and showed a good reproducibility. The discrepancy between the methods, limited to about 14% on the average, when the same air intake was used on both samplers, was not significantly different from zero, based on 24 samples.