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Construction workers
who sand drywall joint compound are often exposed to high
concentrations of dusts and, in some cases, respirable silica.
Drywall joint compounds are made from many ingredients (i.e., talc,
calcite, mica, gypsum, silica). Some of these have been associated
with varying degrees of eye, nose, throat and respiratory tract
irritation.
Over time, breathing the dust from drywall joint compounds may cause
persistent throat and airway irritation, coughing, phlegm
production, and breathing difficulties similar to asthma. Smokers or
workers with sinus or respiratory conditions may risk even worse
health problems. When silica is present, workers may also face an
increased risk of silicosis and lung cancer.
A recent NIOSH Health Hazard Evaluation (HHE) found that drywall
sanders were exposed to as much as 10 times the permissible exposure
limit (PEL) of 15 mg/m3 for total dust set by the Occupational
Safety and Health Administration (OSHA). The OSHA PEL for respirable
dust (5 mg/m3), the very small particles that can go deep into the
lungs, was also exceeded.
Drywall joint compound manufacturers recognize that workers might be
exposed to too much dust during drywall sanding. NIOSH studied five
manufacturers material safety data sheets that
warned workers to avoid generating dust and to use respiratory
protection when dry sanding. Four of the MSDSs told construction
workers to use wet sanding whenever possible, and the fifth said to
cut dust exposures by ventilation. However, these guidelines are
seldom followed in actual work practice.
Wet sanding is generally avoided because of concerns about drying
time and finish texture. Wet sanding is used to protect equipment or
furnishings rather than to reduce work exposures. When
respiratory protection is worn, it is often used incorrectly with
little thought to training, proper selection or fit.
Vacuum Sanding Systems
Several light-weight sanding systems are now sold to control drywall
workers sanding exposures. These systems use portable vacuums to
capture and remove the dust before the worker is exposed to
it. In 1994, NIOSH studied several of these sanding systems at the
International Brotherhood of Painters and Allied Trades (IBPAT)
Apprenticeship Training Facility in Seattle. NIOSH engineers
compared the dust exposures from three pole-sanding and two
handsanding vacuum control systems with the exposures from
traditional, nonventilated sanding methods.
The five commercially available vacuum sanding controls successfully
reduced dust exposures by 80 percent to 97 percent. Four of the five
sanding controls cut exposures by nearly 95 percent.
If engineering controls had reduced total dust exposures by 90
percent in the HHE case report described earlier, the construction
workers exposures would have remained below the OSHA PEL.
Since the 1994 NIOSH study, more manufacturers are now making
drywall subconsanding
controls to cut dust exposures.
Although NIOSH has not tested these controls, researchers expect
them to perform well. In addition to cutting dust exposures, each of
these new controls has its own special features that will attract
both drywall professionals and the doit-yourselfer.
In addition to lower exposures, vacuum sanding systems can help the
sander, subcontractor, general contractor, and building owner in
other ways.
The dramatic reduction in airborne dust exposures results in a much
cleaner work area during and after sanding. For workers, the clean
working environment is more comfortable; less irritating
to eyes, nose, and throat; and less likely to require respiratory
protection. For the subcontractor, a comfortable worker is likely to
be more productive, be absent less often, and require fewer breaks
for fresh air. The savings and reduced regulatory liability given by
lower respiratory protection
requirements will be passed from the subcontractor to the building
owner.
Other cost savings will result from a cleaner environment that
reduces dirt, cleanup time, and repair or repainting of stained
floors and carpets.
Pole-Sanding
NIOSH study results suggest that the construction workers dust
exposures might be cut simply by changing from handsanding to
pole-sanding. This change is even more important when working
overhead.
The pole increases the space between the worker and the sanding
surface, which in turn reduces the amount of dust close to the
workers nose and mouth.
Preventing Silicosis
Silicosis is permanent lung damage caused by breathing dust
containing extremely fine particles of crystalline silica, which is
found in materials such as concrete, masonry and rock. When these
materials are made into a fine dust and suspended in the air,
breathing in these fine particles can produce lung damage.
Silicosis can be totally disabling and may lead to death.
Activities where silica dust may be present in the air include:
• Abrasive blasting using silica sand as the abrasive;
• Abrasive blasting of concrete;
• Crushing, loading, hauling and dumping rock;
• Chipping, hammering, drilling, sawing and grinding concrete or
masonry;
• Demolition of concrete and masonry structures; and
• Dry sweeping or pressurized air blowing of concrete or sand dust.
The key to silicosis prevention is to prevent dust from being in the
air. OSHA requires dust to be controlled whenever possible. A simple
control may work, for example, a water hose to wet dust down
at the point of generation.
Steps to take:
• Always use the dust control system and keep it in good
maintenance.
• When sawing concrete or masonry use saws that provide water to the
blade.
• During rock drilling use water through the drill stem to reduce
the amount of dust in the air.
• Use dust collection systems that are available for many types of
dust generating equipment. Use local exhaust ventilation to prevent
dust from being released into the air.
• Minimize exposures to nearby workers by using good work practices.
• Use abrasives containing less than 1percent crystalline silica
during abrasive blasting to prevent harmful quartz dust from being
released in the air.
• Measure dust levels in the air.
Respirators should only be used until adequate dust controls are in
place. Respirators should not be the primary method of protection.
If controls cannot keep dust levels below the NIOSH Recommended
Exposure level (REL) then respirators should be used.
Select respirators that provide enough protection. Keeping
respirators fit for use requires continual maintenance.
When they are used, OSHA requires employers to establish a
comprehensive respiratory protection program. Respiratory protection
programs are outlined in the NIOSH Guide to Industrial Respiratory
Protection. FSM
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