There are many potential sources of particulate matter and silica from sand operations, including the following:
· Stack emissions
· Fugitive dust emissions
· Blasting of sandstone formations during mining activities.
· Frac sand mining
· Transport of sand from mine to processing plant
· Frac sand processing
Additional sources of silica exposure include the following:
· Glass production
· Road resurfacing
EPA has published estimates for fugitive dust emissions from industrial sand and gravel operations as follows (Table 4-2 in http://www.epa.gov/ttn/chief/ap42/ch11/bgdocs/b11s19-1.pdf).
While ambient silica concentration data from Wisconsin are lacking, many workplace studies and US and international environmental studies have documented ambient levels (e.g., OEHHA 2005, WHO 2000, Shiraki and Holmén 2002, De Berardis et al., 2007, and Trzepla-Nabaglo et al. 2006). Many of these studies track exposures from sand and gravel operations.
To measure exposure to the most dangerous particulate matter and silica from sand operations, we use equipment that filters out the large particles and measures the small particles, called "respirable" particles. There are three ways to measure these particles: a particle counter, a mass counter, and a filter. In each case, air containing silica is pulled through a device to count or collect the silica particles.
Outdoor particulate air monitors such as the one above cost $2,500-10,000 (http://www.ecotech.com.au/particulates-categories/particulate-samplers, https://fscimage.fishersci.com/images/D16583~.pdf).
The Concerned Chippewa Citizens groups has set up a network of 11 Dylos particulate monitors (top image) near the Chippewa Falls EOG sand processing plant: http://wisair.wordpress.com/st-josephs-hospital-monitor/