Dose calculations for diameter distributions of aerosol particles
In case the aerosol particle diameter is a distribution rather than a deterministic value, the dose metric calculations change as follows.
It is assumed here that particle diameter distributions PM(δ) are mass (or equivalently: volume) distributions, i.e. PM(δ)dδ gives the fraction of the total mass (volume) of the particles with diameter between δ and δ+dδ.
The relation between the normalized diameter distribution PM(δ) and the actual (non-normalized) diameter distribution P(δ) is given by
When considering a distribution of the diameter of the aerosol particle, the dose metric calculations of the ‘surface area aerosol particle’ and ‘number of aerosol particles’ change to:
Surface area aerosol particles:
Number of aerosol particles