HPM Particle Sensor

The Honeywell HPM Series Particle Sensor is a laser-based sensor which uses the light scattering method to detect and count particles in the concentration range of 0 μg/m3 to 1,000 μg/m3 in a given environment. A laser light source illuminates a particle as it is pulled through the detection chamber. As particles pass through the laser beam, the light source becomes obscured and is recorded on the photo or light detector. The light is then analyzed and converted to an electrical signal providing particulate size and quantity to calculate concentrations in real time. The Honeywell particle sensor provides information on the particle concentration for given particle concentration range. [source]

I have organized one sensor for demonstration purpose, plugged to my ATMega8 Modul and running continuous measurements. Of course there are more commands available however not used at this time.

The sensor itself runs at 5V/80mA (it has a fan inside to suck in the air), which needs to be considered in case you're using a battery powered application.