CPWR – Center for Construction Research and Training
One of the most dangerous kinds of dust you can breathe is crystalline silica. Silica is in sand,
rock, masonry, concrete, and some paints. (Quartz is silica.) You can be exposed to silica when
you work with these materials in abrasive blasting, cutting/sawing, jackhammering, grinding,
drilling, crushing, or dry sweeping - or during demolition of concrete or masonry structures.
In the lungs, silica
can cause silicosis, which scars air sacs and keeps oxygen from
getting in the blood. Silicosis can cause shortness of breath. Sometimes
it can kill you. And it increases your chance of getting tuberculosis
(TB) and lung cancer. Many industrial countries have restricted the use
of silica sand for sandblasting.
Silicosis usually takes about 20 years to develop, but you can get it after 5 to 10 years; it depends
on how much silica you are exposed to and if you are protected. Or you can get silicosis after a
few weeks if you work in thick clouds of crystalline silica and you are not protected. (This
happened to tunnel workers who cut through hard rock and were not protected.) You can be in
danger even if you do not see dust. Silicosis can get worse years after you are away from the
OSHA has rules about
levels of silica (and other dusts). For more information, call your
local union, the National Institute for Occupational Safety and Health (1-800-35-NIOSH
OSHA (1-800-321-OSHA or www.osha.gov),
or CPWR – Center for Construction Research and Training (CPWR) (301-578-8500 or www.cpwr.com
). (CPWR has a hazard alert card about respirators.) Or go to www.elcosh.org.
- Wet down dry
materials and surfaces before you work with them
or before you sweep them. Use equipment with water sprays. Or use a
HEPA vacuum. This will cut down on the dust.
- Use local exhaust
ventilation to reduce airborne dust where it originates.
- For abrasive
blasting, replace silica sand with safer materials. The U.S. governments
National Institute for Occupational Safety and Health (NIOSH) says do
not use sand or any abrasive with more than 1% crystalline silica in
it. Specular hematite (iron oxide) or steel grit may be safer
substitutes. (A study by NIOSH found hematite was less toxic than some
other substitutes.) But if you use some slags or steel grit, you may
be exposed to some toxic metals. Because there is silica in concrete
and some paints, even if you dont use sand for abrasive blasting
on them, you can be exposed to silica.
- When doing
abrasive blasting, you need to use a type CE abrasive blasting respirator
(positive pressure/pressure demand, with an APF of 1,000 or 2,000).
This respirator provides air from outside the blasting area. Respirators
must not be the main way you reduce exposures. There should also
be effective engineering controls and air sampling must be done during
the work. Use only a NIOSH-approved respirator (If a respirator
is NIOSH-approved, chemical cartridges, particulate filters, and the
box it comes in will say "NIOSH." Self-contained breathing apparatus
will have a NIOSH label on the backpack.)
- When drilling
in rock that may contain silica, you may need a respirator.
The type of respirator you need will depend on the silica concentration
- If you need a
respirator, OSHA says you must have a full respiratory protection
program. This means correct selection and fitting of respirators,
medical clearance of workers for fitness to wear a respirator, and worker
training to use the respirators. Correct storage and cleaning of respirators
and an evaluation of the program are also needed. Your employer must
have a written safety-and-health program too.
- Do not eat,
drink, or smoke near silica. Wash your hands before you eat, drink,
- Change out
of your work clothes before you go home. This limits the dust you
and your family are exposed to.
CPWR has free hazard alerts on Safe Work with Power Saws and Air-Purifying
Respirators (You can get these in English or Spanish.)
This document appears in the eLCOSH website with the permission of the author
and/or copyright holder and may not be reproduced without their consent.
eLCOSH is an information clearinghouse. eLCOSH and its sponsors are not
responsible for the accuracy of information provided on this web site, nor
for its use or misuse.
© 2003, CPWR – Center for Construction Research and Training. All rights reserved. CPWR is a research, development, and training arm of the
Building and Construction Trades Dept., AFL-CIO: CPWR, Suite 1000, 8484 Georgia Ave., Silver Spring, MD 20910. (Edward C.
Sullivan is president of the Building and Construction Trades Dept. and of CPWR and Joseph Maloney is secretary-treasurer.)
Production of this card was supported by grant CCU317202 from the National Institute for Occupational Safety and Health and grants
U45-ES09764 and U45-ES06185 from the National Institute of Environmental Health Sciences. The contents are solely the
responsibility of the authors and do not necessarily represent the official views of NIOSH or NIEHS.
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