This image is from Wisconsin Watch
With the increase in fracking comes a demand for sand used to keep hydraulic fractures open. Not just any sand will do-- it has to have the right particulate size, and therefore is best sourced by crushing and sorting sandstone. To read a summary of silica monitoring, see the wiki page I just made.
Particle Monitoring for Silica
As I pointed out in the Silica wiki page, most dust monitoring has traditionally occurred in occupational environments where the total dust exposure was assumed to be largely of the particles of concern. In a fenceline community, dust could be from any number of sources, so particulate characterization becomes key. Gross particulate measurements such as PM10(For an overview of particle monitoring terms, see the wiki) require correlation with Wind direction, local soil conditions, and a variety of factors. These correlations will require some sort of identification of silica.
Polar Light Microscopy
Scanning dust that has settled on a sticky pad or in a filter has been a method of dust monitoring. with a high-quality scanner or microscope and polarized light microscopy, could silica be picked out? the silica particles above are the most colorful. Other methods that are traditionally used involve X-rays.
There might also be an infrared method of analysis, detailed in this paper. I have to get it and read it: Pandurangi, R. S.; Seehra, M. S.; Razzaboni, B. L.; Bolsaitis, P. (1990) Surface and bulk infrared modes of crystalline and amorphous silica particles: a study of the relation of surface structure to cytotoxicity of respirable silica. Environ. Health Perspect. 86: 327-336.