The screenshot below is from MIT's Erik Velasco's presentation Particle exposure and dosage on public transport. My question is about the small, portable Black Carbon (BC) monitor.
From my reading, Black Carbon refers to mostly carbon particles, mostly produced in natural and anthropogenic combustion processes (e.g. forest fires, vehicles...). Unlike most of the particles that fall into the PM10 and PM2.5 classifications, it seems that a very important fraction of BC comes from very small particles of the order 0.1 microns since they are formed during a short time during combustion.
0.1 micron particles are hard to detect using laser scatterometry since they scatter very weakly compared to the larger particles, and the size of the portable meter shown seems quite small for an advanced scatterometer.
Question: How do small, portable Black Carbon (BC) Monitors work? I believe this one is called a Micro-Aethalometer in the presentation; what basic principles do they use to quantify BC in the air that fits in such a small form factor?
From Particle exposure and dosage on public transport, open image in new window for full size.
From The Aeroflex: A Bicycle for Mobile Air Quality Measurements, Bart Elen et al. Sensors 2013, 13, 221-240; doi:10.3390/s130100221 open image in new window for full size.