1 / 30

SILICA 101 A PRIMER

SILICA 101 A PRIMER.

lcarol
Download Presentation

SILICA 101 A PRIMER

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SILICA 101 A PRIMER

  2. This training module is designed to give the viewer an overview of silica hazards and controls. Included will be suggestions on how to conduct silica inspections, how to find sources of silica information on the web, and how to protect yourself at sites where silica is present.

  3. Silica Properties/Hazards Silica is found abundantly in nature and in industry. Common uses include glassmaking, sandblasting, foundries, pottery manufacturing, granite countertop fabrication and various construction jobs including tuck pointing and road building. Silica is one of the components of Portland cement, so if you see concrete you will see silica.

  4. Silica causes silicosis—a disease where scar tissue develops in the lungs and reduces the ability to get oxygen from the air. There are three kinds of silicosis based on the amount of exposure and length of time of exposure: CHRONIC usually develops after 10 or more years of exposure and is the most common type; ACCELERATED develops between 5 and 10 years of moderate exposures; ACUTE develops within weeks up to 5 years of exposure to massive doses.

  5. WHY TARGET SILICA? OSHA targets silica because it is such a serious disease and exposure is so common. NIOSH estimates that 1.7 million U.S. workers are currently exposed to silica.

  6. Joint Approach In 1996 there was a joint effort between OSHA, MSHA and NIOSH to reduce and eliminate workplace exposure to silica and silicosis. OSHA published an SEP—Special Emphasis Program for Silicosis on May 2, 1996. This program established an outreach and inspection targeting program to put an emphasis on eliminating silica hazards.

  7. Exposure Limits There are several exposure limits for silica. OSHA has limits for quartz, cristobalite and tridymite and separate levels for construction and general industry. ACGIH has a TLV of 0.05 mg/m3 for respirable quartz and cristobalite. NIOSH as a REL of 0.05 mg/m3 for respirable quartz, cristobalite and tridymite.

  8. OSHA Limits GENERAL INDUSTRY QUARTZ (mg/m3)– 10 / (% silica + 2) CRISTOBALITE – ½ the calculated quartz formula TRIDYMITE – ½ the calculated quartz formula CONSTRUCTION QUARTZ (mppcf)– 250 / % silica + 5

  9. What does this mean? The general industry PEL is in mg/m3 and the % silica is analyzed from the sampling filter. That’s right—it changes with the % of silica on the filter. The higher the % silica, the lower the PEL. If no silica is detected the PEL is 5.0 mg/m3 which is the PEL for nuisance dust. If 100% silica is detected the PEL is 0.098 mg/m3. But what’s a mppcf? And how am I supposed to measure it?

  10. Wake up!!! Time to begin confusing calculations!!

  11. MPPCF vs MG/M3 No one samples or analyzes for million particles per cubic foot anymore. This is an obsolete method that uses impingers and technology has advanced since the construction standard was adopted. We have to measure in mg/m3 and convert to mppcf. Fortunately, NIOSH has devised a formula to convert mppcf to mg/m3.

  12. HOW AM I SUPPOSED TO KNOW THIS? • The only way to know the conversion is to read this power point. OR—you can find it hidden on the Intranet at: http://merlin.osha.gov/compliance/memos/ra20010904.pdf • The formula is: CN, mppcf = (CM, mg/m3) / 0.1 • So, if you collected a respirable dust sample at 2.0 mg/m3, the equivalent count concentration would be: CN, mppcf = 2.0 / 0.1 = 20 mppcf Of course you could just multiply the mg/m3 by 10 to get mppcf but that’s too easy.

  13. Now I’m REALLY Confused • You should be confused-this is a confusing concept. But you CAN figure it out!! • To determine silica exposure for OSHA purposes you must calculate two things: the PEL and the employee exposure. Then you compare the employee exposure to the PEL to see if you have overexposure.

  14. What If I Find Quartz and Crystobalite? That’s great!! Then you can use the mixture formula and cite 1910.1000(d)!! OSHA has a silica etool that shows you how to do this.

  15. How Do I Do THAT? If you can do an 8-hour time-weighted average using two or more samples, you can calculate a silica PEL using two or more samples. All you have to do is a “weight-weighted” average using the % silica and weight of each sample. An excellent example of this is listed on the OSHA silica etool at http://www.osha.gov/SLTC/etools/silica/compare_to_limit/pel/pel.html

  16. The GENIUS Method Now that you know how to do those confusing calculations, here’s the easy way. Just click on the OSHA etool website and the Genius will do the calculations for you!! Just click here to begin: http://www.osha.gov/SLTC/etools/silica/compare_to_limit/genius/genius.html

  17. Cautionary Note/Great Advice A common mistake in calculating silica exposures is to correctly calculate the PEL using the % silica formula, but instead of comparing the calculated PEL to the amount of respirable DUST containing silica, the consultant will compare the PEL to the amount of respirable SILICA in the sample. Please be very careful when making calculations—or especially when reviewing sampling results from consultants—to make sure the calculations are done properly.

  18. How Do I Sample? Since the PEL is for respirable dust, you have to use a cyclone. Sample using pre-weighed filters at 1.7 lpm. Directions are on the Intranet at: http://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html#ii:1_5 Read them and follow them EXACTLY!! Ask for both quartz and cristobalite in the analysis.

  19. Possible Violations REMEMBER THAT OSHA DOES NOT HAVE AN EXPANDED SILICA STANDARD but there’s still lots we can do: • 1910.1000(c) and (e)-overexposure and engineering controls for general industry • 1926.55(a) and (b)-overexposure and engineering controls for construction • 1910.132 and 1926.95-require tyveks or coveralls to keep the dust at work • 1910.134-respirator violations

  20. Possible Violations • 1910.134(e)(1)-respirator medical monitoring-although extensive medical monitoring is not required under the OSHA silica standards, medical evaluations ARE required under the respirator standard and more extensive medical monitoring can (and should) be required during settlement negotiations. • 1910.1200-pay particular attention that hazard communication training includes silica hazards

  21. Possible Violations • 1910.1200(f)-labeling, especially concrete slabs • 1910.22(a)(1)-housekeeping, piles of silica should be cleaned promptly • 1910.94(a)-abrasive blasting, lots of requirements about the blast enclosures and PPE • 1926.21(b)(2)-training

  22. Protect Yourself!!! • Wear your respirator with N-100 filters • Wear tyveks • Shoe coverings REMEMBER TO KEEP THE SILICA IN THE INDUSTRIAL ENVIRONMENT, NOT IN YOUR CAR OR HOME!!!

  23. SUBSTITUTION, VENTILATION, WET METHODS Numerous controls can be found on the OSHA website www.osha.gov and the NIOSH website www.cdc.gov/niosh SUBSTITITION – is always necessary to control sandblasting exposures unless small parts are being blasted in an abrasive blasting cabinet VENTILATION – can be difficult and time-consuming but is always possible (except for sandblasting) WET METHODS – work well in construction but need LOTS of water Engineering Controls

  24. Sandblasting Controls The only way to reduce exposures in sandblasting is through substitution with a non-silica abrasive Employers do not like to switch even though non-silica abrasives are more effective and less costly You have to convince them that non-silica abrasives will work—they will still need respirators but employees will not get silicosis and employers will save $$$

  25. Sandblasting Controls • The OSHA etool (http://www.osha.gov/SLTC/etools/silica/protect_against/protect_against.html ) has a detailed discussion of non-silica abrasives including a cost-comparison example • Review 1910.94(a) for possible abrasive blasting violations • Remember 1910.244(b) for deadman control on the blasting nozzle

  26. Miscellaneous Inspection Tips • Silica is an IARC Class 1A Carcinogen-probable human carcinogen-and must be included on a MSDS if 0.1% or greater is in a product • N-95 respirators are allowed for routine overexposures • Remember there are other health hazards on silica inspections • Noise • Other air contaminants (metals, formaldehyde, etc.) • Beryllium (found in the abrasive black beauty) • Every silica overexposure can be eliminated – don’t take TECHNICAL ABATEMENT for an answer!!

  27. OSHA References • Silica, crystalline safety and health topics page-this contains everything that OSHA knows about silica and everything that you should know, too http://www.osha.gov/SLTC/silicacrystalline/index.html • Silica etool-designed for employers and employees, fun to use, great place to begin http://www.osha.gov/SLTC/etools/silica/index.html

  28. OSHA References • Silicosis outreach materials-the quickest way to get a copy of the SEP http://www.osha.gov/Training/Silicosis.html • Silica slide presentation-discusses everything you ever wanted to know about silica analysis, but not sampling—good for general information OR if you’re going to court http://www.osha.gov/SLTC/multimedia.html

  29. Other References • NIOSH has a silica safety and health topics page with lots of good stuff http://www.cdc.gov/niosh/topics/silica/default.html • The Marble Institute of America has an alliance with OSHA and has produced several CDs on safety/health issues http://www.marble-institute.com/

More Related