Air particulate matter measurement
Types of measuring devices
The principal method is based on the gravimetric approach of measuring the mass gain of a given particulate size fraction collected on a filter per unit volume of air sampled. The typical mass loadings on filters for the low to medium volume samplers are less than 5 mg and many chemical species are present at levels of less than 1 μg for a sampling period of 24 hours. Page 149
from Sean Boyce:
Might be able to get something working using the principle by which ionizing smoke detectors work, using a lower voltage than an electrostatic precipitator:
"An ionization type smoke detector is generally cheaper to manufacture than an optical smoke detector; however, it is sometimes rejected because it is more prone to false (nuisance) alarms than photoelectric smoke detectors. It can detect particles of smoke that are too small to be visible. It includes about 37 kBq or 1 µCi of radioactive element americium-241 (241Am), corresponding to about 0.3 µg of the isotope. The radiation passes through an ionization chamber, an air-filled space between two electrodes, and permits a small, constant current between the electrodes. Any smoke that enters the chamber absorbs the alpha particles, which reduces the ionization and interrupts this current, setting off the alarm."