Introduction of fractal-like agglomerates to the algorithm for calculating surface area concentrations of PM1

A method of estimating, in urban indoor environments, human exposure to particulate matter with aerodynamic diameter of less than 1m (PM1, also referred in the literature as fine-mode or nanometer (nm) particulate matter) is proposed. It defines a measure of exposure as a surface area concentration of PM1 and the means of its calculation. The calculation algorithm was constructed using statistical parameters of particulate matter lognormal distribution, with the use of Hatch-Choate equations and the Maynard method, and extended by the accumulation stage physics of PM1 fraction, including Eggersdorfer's and Pratsinis's findings. Introduction of structure and dynamics of fractal-like agglomerates into the calculation algorithm significantly increased estimation accuracy of surface area concentrations, in relation to the standard Maynard method, which calculates surface area concentrations of only spherical particles.