Silicosis in Construction. Edison Electric Institute April 23, Christy J. Jennings, ARM, COHC SafeMetrics LLC

Transcription

1 Silicosis in Construction Edison Electric Institute April 23, 2013 Christy J. Jennings, ARM, COHC SafeMetrics LLC 1

2 I. What is Silica? Composes 15% of Earth s Crust 1. Crystalline Silica (regulated) has a diagnostic X-ray diffraction pattern 2. Amorphous Silica (not regulated) without form cannot distinguish by X-ray diffraction Glass is common example SafeMetrics, LLC 2

3 What is Silica? Silica is Quartz Quartz (silica) is found naturally in almost all rock, sand and soil. It is also found in concrete products and bricks. It is sometimes found in sandblasting (abrasive blasting) grit and is called silica sand. 4

4 Crystalline Silica Examples: Sand, Granite, other Hard rocks Quartz, most common Cristobalite, Tridymite Much less common, but more toxic than quartz 4

5 Why Target Crystalline Silica Exposure? 1. Toxicity is well documented 2. Widespread worker overexposure 3. Exposures can be controlled 5

6 Case Study, 1930 s: Hawk s Nest Tunnel Gauley Mt., W. VA Estimated Deaths from Silicosis: 500 to 750 6

7 Progress made: Exposures in the 21 st Century 7

8 II. Silica and Mortality 250 Worker deaths per year from Silica (Compare to 175 deaths/yr from trenching accidents) Silicosis Tuberculosis Heart Disease Lung Cancer? Suspect Hum. Carcinogen A2 (ACGIH) 8

9 Silica Health Hazards Inhaled silica dust scars the lungs A lung disease called silicosis is caused by breathing of dust containing silica. The dust causes fibrosis or scar tissue formation in the lungs. This reduces the lung s ability to extract oxygen from the air. There is no cure. 5

10 Silicosis Diagnosis Requires Chest X-ray X-ray must be read by qualified B- Reader Silica Nodules are Non-Reversible 10

11 Health Effects Chronic-Obstructive Pulmonary (Lung) Disease--COPD Affects Aveolar Surface Decreases Elasticity Prevents Oxygen/CO2 Exchange 11

12 Disease Classes of Silicosis 1. Acute Silicosis (Highest Exp.) Latency of weeks to 5 years 2. Accelerated Silicosis (High Exp.) Latency of 5 to 15 years 3. Chronic Silicosis (Moderate Exp.) Latency >15 years 12

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15 III. Silica Special Emphasis Program Began in 1997 Part of OSHA current Strategic Plan (through 2008) Compliance Enforcement Consultation Training and Outreach OSHA Web-site 15

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17 Silica New Construction Based Standard Proposed As of September 2012, the crystalline silica permissible exposure limit (PEL) for the construction industry at 29 CFR (a) is expressed in terms of millions of particles per cubic foot (mppcf). This PEL is based on a particle count method long rendered obsolete by respirable mass (gravimetric) sampling, which yields results reported in milligrams per cubic meter (mg/m3) A formula is available to convert from mg/m3 to mppcf for compliance purposes 17

18 Silica New Construction Based Standard Proposed The new standard will be based on gravimetric methods and will eliminate the need for conversions. OSHA used a benchmark of 0.1 mg/m3 of respirable silica dust in its 2009 guidance for controlling silica exposures in construction. The agency indicated that since this benchmark is generally more conservative (lower) than the construction PEL, employers who meet the benchmark will also be in compliance with the obsolete construction PEL. The PEL options under consideration by OSHA for the proposed new silica rule are 0.1 mg/m3 and 0.05 mg/m3 of respirable silica dust. 18

19 IV. Potential Silica Exposures Foundries Ceramics Industry Abrasive Blasting Construction Manufacturing of cleaning agents Mining Operations Use of Coal (e.g., electric power generation) 19

20 Silica Exposure in Construction Concrete Work Jack-hammering Power sanding Generates moderate to heavy amounts of dust Generates heavy amounts of dust 12

21 Silica Exposure Rock Drilling Rock drilling without water produces large amounts of dust. Drilling without water Your actual exposure will depend on the wind, where you stand and if you use water to control the dust. 11 Drilling with water

22 Silica Exposure brick and cinder block cutting Without water With water Generates moderate to heavy amounts of dust without water. 15

23 10% Crystalline Silica Quar

24 Georgia Tech Safety and Health Consultation Program 24

25 Georgia Tech Safety and Health Consultation Program 25

26 Georgia Tech Safety and Health Consultation Program 26

27 Georgia Tech Safety and Health Consultation Program 27

28 Georgia Tech Safety and Health Consultation Program 28

29 8 % Crystalline Silica Quartz 10% Crystalline Silica Quartz

30 Georgia Tech Safety and Health Consultation Program 30

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34 V. Silicosis: Non-Curable Disease Prevention through Safe Workpractice is critical 34

35 Silicosis Prevention Program Engineering Control of Dust Training on crystalline silica Respiratory protection program Work clothes, change and wash area 35

36 Silicosis Prevention Program Air monitoring program Medical surveillance Housekeeping and Regulated Areas Recordkeeping 36

37 OSHA s Advisory Committee for Construction Safety and Health (ACCSH) Utilize a competent person approach for the upcoming proposed silica in construction rule current regulation and will also need to be familiar with features of the new OSHA silica standard perform air sampling only under the direct supervision of an industrial hygienist (qualified person). 37

38 Silica dust exposure can be controlled by use of water or exhaust ventilation Using water to cut concrete and bricks Concrete sander with exhaust ventilation 20

39 Silica Exposure Control Avoid dry sweeping and use of compressed air on concrete Both these activities can stir up large amounts of dust. Use a vacuum with high efficiency filters when possible. 22

40 Silica Overview Silica-It s not just dust Silicosis is irreversible and prevetable Present in a variety of construction based task including maintenance, and work performed during facility outages. New standard proposed for Silica in construction Questions? 40