# How to convert from ppm to ug/m3 in case of PMx?

For $\text{PM}_{10}$, $\text{PM}_{2.5}$ sensors, sensitivity, minimum and maximum recordable concentrations are generally expressed in $\pu{ppm}$ (parts per million) while legislation uses $\pu{\mu g / m^3}$ or $\pu{mg / m^3}$.

For gases you usually use the molar mass to convert from one to the other. Since PM is composed by heterogeneous particles how can I convert $\pu{ppm}$ to $\pu{\mu g / m^3}$? Is there an approximate weight for each type of PPM?