Laborer Dies of Carbon Monoxide Poisoning During Sandblasting Operations in Virginia

INVESTIGATION

The victim had been assigned the task of sandblasting two wrought iron chairs the day before the incident. The victim performed the sandblasting operations at the dealership as necessary, but not on a daily basis. The sandblasting unit consisted of a diesel-powered air compressor, two 1-inch-diameter air discharge lines (one to the air-blasting nozzle, one to the air-filtration unit), the air-filtration unit, a vortex/control valve (to control air flow and cool the air), and the abrasive-blasting airline respirator (a continuous flow airline Type "CE" respirator, with a hood and facepiece that covered the wearer's head, neck, and shoulders to protect against rebounding abrasive) (Figure). The air compressor had been purchased by the dealership 5 years before the incident.

Early that afternoon, the victim told the shop foreman that the filter in the filtration unit needed to be changed because the supplied air smelled stale. No filters were available at the dealership, so the victim drove to a supplier and obtained the filter, then returned to the dealership and changed it. The victim told the shop foreman that he would finish sandblasting the chairs early the following morning before the sun got hot.

The victim began sandblasting the chairs at 8:00 a.m. the following morning. At 9:00 a.m., the victim was found lying on the ground unconscious, but breathing, still wearing the abrasive-blasting respirator.

Investigation of the air compressor unit revealed several factors that might have contributed to this fatality:

• the vanes of the compressor's radiator were clogged

• the engine of the air compressor was extremely low on oil to the point where it had seized and could not be started at the time of the investigation

• evidence of combustion or extreme heat was present at the back end of the compressor (opposite the two discharge lines)

• the main discharge line was broken in an area located underneath the evidence of combustion or extreme heat

• three electrical safety relays-that would detect high ambient, oil, or discharged air temperature and automatically shut the compressor down-had been bypassed

• the filter in the filtration unit offered no protection against toxic gases; it could only filter out solid particulates and liquid aerosols.

• a black, oil-like residue was present in both discharge lines and, to a greater extent, in the air filtration unit.

The filter that had been replaced did not exhibit the black oily residue present on the new filter. Residue samples obtained by the DSR investigator were analyzed for evidence of combustion, but the analysis was inconclusive.

The event was unwitnessed but it is assumed the following occurred. The compressor began to overheat either because of a low oil level or because of the clogged radiator vanes. The engine and engine oil became extremely hot, but the engine did not shut down because the safety relays were inoperable. The hot oil began to smoke and possibly burn. Smoke and carbon monoxide passed through the discharge line to the victim's abrasive-blasting respirator, and the victim was overcome. Although unconscious, the victim was still wearing the respirator and continued to inhale the carbon monoxide. The emergency medical service (EMS) was summoned and transported the victim to the hospital where he was pronounced dead by the attending physician.