Method and apparatus for measuring suspended particulate matter

An apparatus for measuring suspended particulate matter in the atmospheric air, the comprising:

• a container;
• a pump for sucking the atmospheric air into the container;
• a discharging electrode, which is arranged in the container, for electrically charging the suspended particulate matter in the container by generating single-pole ions;
• a dust collecting electrode, which has an electric potential difference with respect to the discharging electrode, for collecting the suspended particulate matter, which has been electrically charged in the container by the discharging electrode;
• a dispersing mechanism for dispersing the suspended particulate matter collected by the dust collecting electrode;
• an irradiating optical system for irradiating the dispersed suspended particulate matter with laser beams;
• a measuring optical system for measuring a spatial intensity distribution of light which has been diffracted and scattered by the suspended particulate matter when the suspended particulate matter is irradiated with laser beams;
• and
• a calculation section for calculating a particle size distribution of the collected suspended particulate matter from the result of measurement.