Empirical models to predict parsimoniously the mass and number concentrations of ultrafine particulate in ambient atmosphere.

The main objective of this study was to develop parsimonious empirical models for predicting the mass and number concentrations of ultrafine particulate (UFP, aerodynamic diameter < 0.1 or 0.18 microm) in the atmospheric environment. We found strong correlations existed between the mass/number concentration of UFP and the mass concentration of PM(2.5) (aerodynamic diameter < 2.5 microm) by fitting the experimental data. Therefore, we were easily able to obtain UFP mass and number concentrations by using the presented empirical models. The empirical equations should be used with care since limitations existed.