The National Institute for Occupational Safety and Health (NIOSH) recently posted information on its Web site that alerts roofing industry workers to the hazards of respirable silica. The silica issue has come to the forefront in the roofing industry after recent NIOSH testing showed worker exposures exceeded the Occupational Safety and Health Administration's (OSHA's) permissible exposure limit during cutting of concrete and clay roofing materials. (See "Understanding a complex killer," August 2005 issue, page 36.)
The danger with regard to inhaling respirable crystalline silica is a lung disease called silicosis. Respirable silica, the sand portion of cut concrete or clay, enters the lungs and causes inflammation and scarring. The result is reduced lung capacity. Silicosis is an insidious disease—its effects may not become apparent until years after an initial exposure to respirable silica. The lung damage from silicosis is irreversible.
Silicosis is a problem usually associated with workers who do sandblasting, rock drilling and building demolition. According to NIOSH, each year, 200 workers die from the disease. Additionally, NIOSH estimates more than 1 million workers are at risk for developing silicosis each year.
Taking action
The first step to addressing this issue is to review manufacturers' material safety data sheets for the presence of silicon dioxide in concrete or clay roofing materials. Respirable silica is generated when tiles containing silicon dioxide are cut in a manner that produces particles small enough to inhale. This ordinarily is done with a dry-cutting technique involving the use of gasoline-powered tile cutters with diamond blades that produce large amounts of dust that contains respirable silica. Clearly, it is not merely workers doing the cutting who are exposed to respirable silica. Nearby workers and passersby also may be subjected to a dust cloud of silica particles. Exposures can be compounded if workers use leaf blowers to clean a roof subsequent to dry-cutting operations. Dry cleaning is preferred because wet cleaning of the residue can stain the newly installed roofing tiles, causing permanent damage.
NIOSH suggests the following engineering controls to reduce worker exposure to silica:
Unfortunately, wet-cutting methods have been shown to be dangerous to workers at elevated heights and damaging to roofing materials. Similarly, vacuum attachments to capture respirable silica do little to reduce exposure levels sufficiently. A cutting station on the ground may limit exposures of some workers but has significant practical limitations for job efficiency.
You should consider monitoring roofing workers engaged in concrete or clay tile installations to ascertain the extent of the silica hazard. Any engineering controls that effectively reduce the amount of silica dust while not introducing additional hazards on the roof, such as water, should be implemented. NIOSH recommends the use of an N-95 filtering facepiece respirator (dust mask) to reduce silica exposure during cutting operations involving concrete and clay roofing tile. If you require employees to use respirators to protect them from silica, OSHA says you must establish a written respiratory protection program under 29 CFR 1910.134 of the OSHA General Industry Standards. The required elements include:
Future plans
NRCA is in the process of assessing the scope of risks to roofing workers installing concrete and clay products. Roofing professionals are encouraged to contact NRCA with results of any air monitoring they may conduct.
Harry Dietz is NRCA's director of risk management.
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