In field testing, these samplers have been demonstrated to vary (CV) only 11.6% from [Federal Reference Methods](/wiki/pm-monitoring-regulations), when measuring course particulates (PM10-2.5), making this the most precise published passive particle monitor design (Ott, Cyrs, & Peters, 2008).  Public Lab is evaluating the deployment of this technology. 

[Read More](/wiki/SEM-stub-pm)

Developed originally for indoor dust monitoring at the University of North Carolina by Jeff Wagner and David Leith, this tiny monitor (in the middle of the housing, below) consists of a fine mesh cap over top of a Scanning Electron Microscopy (SEM) pin stub, a small aluminum object that looks like a pin.  Thomas Peters and Darrin Ott at the University of Iowa added a wind-and-rain housing so the monitors can be used outside.  They also added a glass microscope slide cover on top of the stub, allowing lower-cost analysis with a standard visible-light microscope. 

[![Amber Wise removing a stub cover](//i.publiclab.org/system/images/photos/000/012/171/original/IMG_20151020_175427.jpg)](//i.publiclab.org/system/images/photos/000/012/171/original/IMG_20151020_175427.jpg)

[![IMG_20151015_120027-trim.png](//i.publiclab.org/system/images/photos/000/013/521/medium/IMG_20151015_120027-trim.png)](//i.publiclab.org/system/images/photos/000/013/521/original/IMG_20151015_120027-trim.png)

Analysis is performed in [ImageJ](http://fiji.sc/Fiji). roughly:

[![Analysis Steps](//i.publiclab.org/system/images/photos/000/011/635/original/imagejsteps.jpg)](//i.publiclab.org/system/images/photos/000/011/635/original/imagejsteps.jpg)

[Read More]

Citation: 
Darrin K. Ott, William Cyrs, Thomas M. Peters, Passive measurement of coarse particulate matter, PM10-2.5, Aerosol Science 39:156 – 167, 2008