October 31, 2019

NIOSH: Workers Overexposed to Silica during Fire Debris Cleanup

A recent NIOSH health hazard evaluation of employees’ exposures during fire debris cleanup in California found that many workers were overexposed to respirable crystalline silica. Employees also had metals and polyaromatic hydrocarbons, or PAHs, on their skin, and NIOSH personnel observed some workers not wearing personal protective equipment correctly. The workers involved in this NIOSH evaluation were cleaning up debris from the Carr Fire, which burned more than 229,000 acres in Shasta and Trinity counties in Northern California in 2018. The fire destroyed 1,614 structures, including residences, commercial buildings, and outbuildings. Sixty-one other structures were damaged.

According to NIOSH, remnants of burned residential structures may contain respirable crystalline silica—typically quartz—from demolished concrete used in foundations, walls, and roofing tiles. Items like home electronics and melted vehicles are sources of potential exposures to metals such as lead, cadmium, and aluminum. PAHs are potentially carcinogenic substances found in soot or burn ash. NIOSH stresses that asbestos may also be present in fire debris, depending on the age of the affected buildings.

NIOSH staff visited the Carr Fire cleanup site in September 2018 to observe work practices; measure employees’ exposures to silica, asbestos, metals, and PAHs in air; measure metals and PAHs on skin; and interview employees about their work and health. The agency found that skid steer operators had the highest average exposure to silica and that two operators’ exposure levels were above the OSHA action level and the ACGIH threshold limit value for quartz of 25 μg/m3 as an 8-hour time-weighted average. NIOSH personnel observed several instances where employees did not use dust suppression with water. Some employees were not wearing respirators correctly and others were not wearing them at all. For example, some workers wore respirators over the chin instead of covering the nose and mouth, and others wore respirators when not clean-shaven. Some instances of improper use were not corrected by the task force leader responsible for providing on-site supervision of cleanup crews. When NIOSH investigators sampled 15 employees’ hands at lunchtime, all had metals on them, including lead. Most of the skin wipes also had nondetectable amounts of PAHs. The agency’s evaluation found that employees were not overexposed to asbestos, metals, or PAHs in air.

NIOSH’s number-one recommendation to the employer is to reduce worker exposures to respirable crystalline silica and to educate employees on silica and silicosis. The employer should ensure that water spray is consistently used to reduce dust and require consistent use and enforcement of PPE and decontamination procedures among all contractors and subcontractors. The agency’s evaluation did not include noise dosimetry or audiometry, but its report urges the employer to measure workers’ full-shift noise exposures to determine whether exposures are above NIOSH’s recommended exposure limit for noise of 85 decibels as an 8-hour TWA. According to the agency, noise from construction equipment could expose operators and laborers to noise levels above the REL. NIOSH staff noted that not all employees wore hearing protection during fire debris cleanup.

Further information is available in NIOSH’s HHE report (PDF).

In July, AIHA launched “Think and Act Fire Smart,” an information center for wildfire preparedness and recovery intended to raise awareness about the hidden dangers in the cleanup process that follows a devastating wildfire, especially in urban areas.

Related: An article published in the November 2017 issue of The Synergist, “The ABCs of Wildfire Residue Contamination Testing,” discussed postfire assessments of the indoor environment. “After the Fire,” published in the August 2016 issue, focused on assessing the potential health risks of wildfire residues in the indoor environment.