Abstract
An industrial hygiene study was conducted at a true in situ oil shale retorting facility located near Vernal, Utah. The study was conducted during operation of the first two in situ oil shale retorts of commercial size at the facility. Air samples were collected for analysis of dust and a number of selected gases and vapors, and limited monitoring was conducted for noise. Limited dust monitoring also was conducted during the drilling of blastholes for a third retort. Very low concentrations of dusts, and gases and vapors were observed in most areas above the operating oil shale retorts. Higher concentrations of some gases and vapors were observed in small cracks or leaks in the ground surface above the retorts, near a leaking fan that carried retort off gases, and in a confined area adjacent to tanks used for separation and storage of retort oil and water. Observed breathing-zone air concentrations would not exceed established occupational health standards, even if employees were to be exposed for 8 hr. Low levels of polynuclear aromatic hydrocarbons were measured, but the significance of long-term exposure to these compounds is unknown. The limited air sampling conducted during the drilling of blastholes indicated high dust concentrations in the immediate vicinity of the drilling operation; however, personal sampling of employees indicated their exposures were not excessive. Noise levels generally exceeded 8-hr exposure limits in the immediate vicinity of blowers, but workers were not observed to spend much time in these areas.