Tag Archives: Silica

Wet Cutting Concrete to Reduce Dust Exposure

Safety Articles from Desert Diamond IndustriesWet cutting concrete reduces respirable dust concentrations in the air by up to 85%.

Those are the results of a study by the University of Massachusetts Lowell Department of Work Environment, which was reported on ForConstructionPros.com. They confirm the results of a Centers for Disease Control and Prevention study that we reported on back in July: wet-cutting concrete reduces worker exposure to dust and, more importantly, to respirable crystalline silica (RCS).

These findings are important because breathing in RCS can cause a number of respiratory conditions, including silicosis, COPD, tuberculosis, and lung cancer. The studiers concluded:

Dry cutting with gas-powered concrete saws should not be allowed under any circumstances, unless the firm is prepared to perform personal air sampling to ensure that exposure levels do not exceed acceptable limits. When exposure levels are known, selection of the appropriate respirator can be an effective way to reduce personal exposures, although the dust can still fill the work area and expose other workers and the neighborhood. The regular use of water controls on gas-powered concrete saws is a clear and effective way to reduce the level of respirable dust altogether: for operators, other project workers and the community.

ForConstructionPros.com, “Wetter is Better to Control Concrete Dust

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OSHA’s Proposed Crystalline Silica Rules May Increase Exposure for Construction Workers

Safety Articles from Desert Diamond IndustriesNew exposure rules proposed by the Occupational Safety and Health Administration (OSHA) may increase construction and maritime workers’ exposure to crystalline silica, which causes the potentially fatal but preventable respiratory disease silicosis.

On Aug. 23, OSHA proposed changes to crystalline silica exposure rules that would adjust permissible exposure levels (PELs) to 50 micrograms per cubic meter (mg/m³) over an eight-hour period in the general, maritime and construction industries. OSHA currently limits crystalline silica exposure to 100 mg/m³ over an eight-hour period in general industry and 250 million parts per cubic foot (mppcf) in the construction and maritime industries.

According to OSHA, these changes are long overdue. The current PELs  were adopted in 1971 and haven’t been updated since. The construction/maritime PEL, in particular, exposes workers in those industries to higher levels of crystalline silica than general industry workers, said the agency.

However, the current construction/maritime PEL is actually more rigorous than the proposed one. According to this OSHA conversion formula, the current PEL of 250 mppcf equals 25 mg/m³, or half the proposed PEL of 50 mg/m³. In other words, OSHA’s proposed PEL would halve crystalline silica exposure for general industry workers,  but double it for construction and maritime workers.

These PEL changes, if approved, would disproportionately affect U. S. construction workers. OSHA estimates that about 2.2 million workers are exposed to crystalline silica in the U. S. However, the vast majority of these – 1.85 million – work in construction, where the PEL may be increased.

Silicosis deaths have fallen dramatically in the U. S. over the past four decades, according to the Centers for Disease Control (CDC) – from 1,157 deaths in 1968 to just 148 in 2002. However, workers continue to be exposed to crystalline silica. According to the CDC, 121,000 workers were exposed to levels equal to or higher than a recommended exposure level of 0.05  mg/m³ set by the National Institute of Occupational Safety and Health (NIOSH).

Labor unions have hailed the proposed changes, which they say will protect worker health. Industry groups, on the other hand, have opposed the changes, which they claim will increase construction costs and decrease worksite safety. They have added that OSHA should instead focus on enforcing current crystalline silica rules.

See OSHA’s Crystalline Silica Rulemaking page to see how you can comment on these and other changes to crystalline silica exposure rules.

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