This document specifies a process for the electrical diffusion charging of aerosols with subsequent measurement of particle charge. With the aid of this method, it is possible to determine the lung-deposited surface area (LDSA) concentration of particles in ambient air. Depending on the design of the electrical diffusion charger, the LDSA of particles in the size range of approximately 20 nm to approximately 300 nm is measurable.
Furthermore, this document specifies design criteria for LDSA measuring aerosol monitors as well as performance criteria and the associated test procedures. The performance criteria depend on the application and they are more stringent when the instrument is operated in an air quality monitoring station.
In the determination of the LDSA concentration, the share of geometric particle surface area concentration is determined that can be deposited in the alveolar region of the human lung. Typical particle surface area concentrations with alveolar deposition measured in urban areas range from 5 µm2/cm3 to 50 µm2/cm3.
Instruments based on this measurement principle can be designed to be very compact with a low power consumption. This makes them ideally suited for hand-held measurements, other forms of mobile application or to measure personal exposure. On the other hand, they can be easily adapted to serve as a stationary instrument in air quality monitoring stations.
