CDC Report Renews Concerns over Workers' Exposures during Tank Gauging, Sampling
A report published on Jan. 15 in CDC’s Morbidity and Mortality Weekly Report (MMWR) urges health and safety professionals and healthcare workers who treat or evaluate oil and gas workers to be aware of the risks related to exposure to high concentrations of hydrocarbon gases and vapors (HGVs) and to oxygen deficiency during manual tank gauging and sampling. These tasks require workers to open the “thief” hatch of a hydrocarbon-containing storage tank—a known, concentrated source of HGVs, says CDC. Workers who open these hatches face potential hazards that include “sudden exposure to high concentrations (>100,000 ppm) of low-molecular weight HGVs, accompanied by displacement of air, resulting in O2 deficiency.” The report discusses nine oil and gas worker deaths between January 2010 and March 2015 in which exposure to HGVs was confirmed or suspected. According to CDC, oil and gas workers, who often manually gauge fluid levels and collect samples from storage tanks at well sites, should not work alone in situations that might put them at risk for exposures to high concentrations of hydrocarbons and low-oxygen environments. All nine workers whose deaths were examined in the report were working alone at the time of the incidents, and were either performing tank gauging or collecting a fluid sample. They were all found collapsed on a tank, on a catwalk leading up to a tank hatch, or at the base of catwalk stairs. In at least five of the cases, the storage tank hatch was found open. Three weeks before the death of one worker, he was examined in an emergency room after experiencing altered consciousness while gauging a tank. “Health professionals need to recognize the signs and symptoms of exposure to high concentrations of HGVs and possible O2-deficient atmospheres in oil and gas workers,” the report reads. “Health and safety professionals need to recognize and act on nonfatal warning signs and symptoms, such as dizziness, confusion, immobility, and collapse in oil and gas workers who might have been exposed to high concentrations of HGVs and to O2-deficient atmospheres.”
Three weeks before the death of one worker, he was examined in an emergency room after experiencing altered consciousness while gauging ​a tank.
The authors also note that medical examiners and coroners investigating worksite fatalities should be aware that exposures to HGVs and oxygen-deficient atmospheres can result in sudden cardiac death and urge them to include appropriate toxicology analyses in their investigations. According to MMWR, toxicologic data on HGVs were not consistently collected during autopsy of the nine workers described in the report, but petroleum hydrocarbon vapors were noted as a cause of death for three of the workers. “A thorough worksite assessment is warranted if any workers exhibit signs or symptoms of HGV exposure or oxygen deficiency,” the report states. “Implementation of measures to reduce or eliminate HGV exposures is important, including practices that allow for alternative fluid sample collection points, remote monitoring of fluid levels, proper use of gas monitors, respiratory protection meeting the requirements of the Occupational Safety and Health Administration, and worker training.” Read the full report on CDC’s ​website.