This Technical Report describes the use of photometers for the determination of airborne particles belonging to the respirable fraction and gives details on their limitations and possible uses in the field of occupational hygiene. NOTE Photometers can also be used to detect other size fractions of airborne particles after aerodynamic pre-separation, but these are not the focus of this Technical Report. The method complements existing conventional long-term aerosol particle sampling and can be used for: - instantaneous (direct-reading) measurement, - time-related monitoring, - investigation of space-related aerosol evolution (mapping), and - exposure visualization. The method enables e.g.: - detection and relative quantification of concentration peaks due to specific operations (bagging, sanding, etc.); - identification of most exposed workers with a view to more detailed studies of risks and prevention measures to be applied; and - detection of dust emission sources and their relative magnitudes.