This can increase the risk of injury or fatality. According to the U.S. Bureau of Labor Statistics’ Census of Fatal Occupational Injuries, from 2003 to 2009, work related vehicle crashes resulted in 206 worker fatalities. Activities which may be hazardous include vehicle accidents while traveling to and from well sites, the delivery and movement of large machinery such as mixing or pumping equipment, and the rig-up/rig-down processes In a study conducted in Pennsylvania, Muehlenbachs et al. found significant increases in total and heavy truck accidents in towns with hydraulic fracturing activity versus those without, with each well addition increasing rates of accidents by 2% and risk of fatality by .6%. Rig-Up and Rig-Down are terms used to refer to the delivery, construction, dismantling and breakdown of equipment required throughout the hydraulic fracturing process. Incidents and fatalities during rig-up/rig-down operations may result if struck or crushed by the heavy equipment involved. Hazards during mixing and injection Workers may be exposed to dangerous chemicals while mixing and injecting fluids used in hydraulic fracturing. Potential chemicals include, hydrochloric and hydrofluoric acid, biocides, methanol, ethylene glycol, guar gum, polysaccharides and polyacrylamides, magnesium peroxide, calcium peroxide, magnesium oxide, citric acid, acetic acid, sodium polycarboxylate, phosphonic acid, choline chloride, sodium chloride, formic acid, and lauryl sulfate. Effects of exposure to the chemicals listed vary in severity, but may include, chemical burns, skin and eye irritation, allergic reactions, carcinogenic effects, and toxic reactions from direct contact or inhalation of chemicals. Hazards during pressure pumping and flowback operations Modern day fracking equipment is capable of pumping anywhere from 800 to 4200 gallons of water per minute, at pressures ranging from 500 to 20,000+ psi. Once the injection process is complete and gas has entered the well, anywhere between 10 and 30 percent of the fluid injected will flow back into the well as wastewater for disposal. In addition to the chemical additives present in fracking fluid, flowback water contains dangerous volatile hydrocarbons, such as pulled from the fractured rock. Workers must use handheld gauges to check fluid levels via hatches on top of wells and when doing so they may be exposed to dangerous plumes of gas and vapor containing the volatile hydrocarbons. Exposure to these chemicals and hydrocarbons can affect the nervous system, heart rhythms, and may lead to asphyxiation or death. Additional workplace hazards Spills Workers are exposed to spills in the hydraulic fracturing process both