FINAL COPY. Airborne Asbestos Risk Assessment Basic Medical Sciences Building University of Manitoba, Bannatyne Campus

Transcription

1 COPY Airborne Asbestos Risk Assessment Prepared for: University of Manitoba Environmental Health and Safety 191 Frank Kennedy Centre Winnipeg, Manitoba R3T 2N2 Attention: Mr. Grant McCaughey, P.Eng., CRSP Project Number: W18578 October 25, 2002 PINCHIN ENVIRONMENTAL LTD. 172 MARION STREET, WINNIPEG, MANITOBA R2H 0T4 TEL: (204) FAX: (204) MISSISSAUGA DARTMOUTH MONTREAL OTTAWA TORONTO HAMILTON WATERLOO LONDON SARNIA WINNIPEG

2 TABLE OF CONTENTS 1.0 INTRODUCTION BUILDING INFORMATION AND CURRENT CONDITIONS SCOPE OF WORK METHODOLOGY TEM ANALYSIS PCM ANALYSIS DESCRIPTION OF WORK ACTIVITIES DISCUSSION OF AIR SAMPLING FOR ASBESTOS BY TEM AND PCM ANALYSIS TEM ANALYSIS PCM ANALYSIS FINDINGS VISUAL OBSERVATIONS BACKGROUND SAMPLES ANALYSED BY TRANSMISSION ELECTRON MICROSCOPY (TEM) SAMPLES ANALYSED BY TEM DURING MAINTENANCE ACTIVITIES SAMPLES ANALYSED BY PCM DURING MAINTENANCE ACTIVITIES DISCUSSION AND CONCULSIONS RECOMMENDATIONS...8 APPENDICES APPENDIX I APPENDIX II APPENDIX III APPENDIX IV Background TEM Sample Results TEM Air Sample Results During Maintenance Activities PCM Air Sample Results During Maintenance Activities University of Manitoba Correspondence

3 1.0 INTRODUCTION Pinchin Environmental Ltd. was retained by the University of Manitoba to perform an asbestos risk assessment of regular maintenance activities within the interstitial space at the (BMSB) in Winnipeg, Manitoba. The purpose of the assessment was to assess the impact that regularly scheduled maintenance activities have on known friable asbestos-containing spray. The information gathered from the investigation would be used to assess potential exposure to both maintenance workers as well as other building occupants. This report has been prepared to present the methodologies, findings and conclusions. The following sections of this report describe the collection and analysis of TEM and PCM air samples. Samples were collected prior and during simulated and regular maintenance activities within the interstitial space. 2.0 BUILDING INFORMATION AND CURRENT CONDITIONS The is a seven-storey brick clad steel structure constructed in A service area known as an interstitial space is located above each occupied floor. The interstitial space consists of an open air plenum approximately 6 feet in height. Sprayed asbestos-containing cementitious fireproofing containing 25-50% Chrysotile is present on structural steel members at this height on all levels. As would be expected, asbestoscontaining dust and debris are present on surfaces within the interstitial space. 3.0 SCOPE OF WORK The scope of this assignment consisted of the following: 1. Baseline Air Monitoring; Occupied Area Interstitial Space 2. Visual Inspection of Interstitial Space (IS); 3. Worker Exposure (Air) Monitoring; and 4. Interviews with key maintenance personnel to evaluate frequency of IS access and activities within the area. Air samples collected were analysed by both the Phase Contrast Microscope (PCM) method as well as the Transmission Electron Microscope (TEM) method. This allows comparison to both current Manitoba Labour regulatory criteria as well as other more sensitive and stringent asbestos standards. Pinchin Environmental Ltd. Page 1

4 4.0 METHODOLOGY Prior to the site work, a series of meetings were held with University personnel to discuss and establish the type and frequency of activities within the interstitial space. Work activities to be monitored were established by BMSB Physical Plant personnel. Activities were planned that would be most representative of actual work in these areas. Background samples were collected on June 10, 2002 and June 24, 2002 to monitor airborne asbestos levels prior to any simulated or scheduled maintenance work being performed. Three samples were collected within the interstitial spaces and three samples were collected in the corridors. The samples were analysed by Transmission Electron Microscopy (TEM) method. The following is a summary of the background samples collected: ID Sample No. Location Date Collected 1 N st Floor Interstitial Space June 10, N rd Floor Interstitial Space June 10, N th Floor Interstitial Space June 10, N nd Floor Corridor adjacent Room 230 June 24, N th Floor Corridor across Room 432 June 24, N rd Floor Corridor across Room 432 June 24, 2002 A series of air samples were collected during the scheduled work on July 22, Air samples were collected in the vicinity of work in the IS (Area samples), on the workers (Personal samples), and in the offices area immediately below the work (Occupied samples). Workers were utilizing 1/2-face negative pressure respirators fitted with P100 filters and disposable coveralls while performing work. Visual observations were also made at the same time sampling was being performed to document the work activities as well as observe any asbestos that may be disturbed. The samples were analysed by both Transmission Electron Microscopy (TEM) and Phase Contrast Microscopy (PCM). Pinchin Environmental Ltd. Page 2

5 The following is a summary of the samples collected: ID Sample No. Location Sample Type Date Collected th Floor Interstitial Space Area July 22, Jeff Modjeski Personal July 22, Giuliano Lupinetti Personal July 22, Middle of Room 615A-B Occupied July 22, th Floor Hallway across from Room 615A-B near Fridge Occupied July 22, 2002 Each sample was collected by drawing a predetermined volume of air through a mixed cellulose ester (MCE) filter, having a pore size of 0.45 µm for TEM and 0.80 µm for PCM. The effective collection area on both TEM and PCM sampling cassettes is 380 mm 2. The filter, backed by a 5.0 µm pore-size MCE diffuser filter and cellulose support pad, was held in a 25 mm three-piece conductive cassette with a 50 mm extension cowl. Diaphragm vacuum pumps, fitted with needle valves for flow control, were used in sample collection. The pumps were calibrated using a primary standard before use. 4.1 TEM Analysis TEM air samples were analysed at EMSL Analytical Inc. Laboratories, Williamsville, N.Y. according to the EPA Level II Procedure (formerly Yamate Level II procedure, US EPA Contract , Draft Report dated July 1984). According to the method, a section of each filter is carbon coated, the filter is dissolved away and the carbon film, embedded with the collected particles, is directly transferred to a 200-mesh grid. The grid is then scanned under a Transmission Electron Microscope at approximately 20,000 times magnification. Fibrous particles (structures) meeting specified size criteria are classified as individual fibres, fibre bundles, clusters or matrices. Asbestos structures are sized and identified as Chrysotile or Amphibole (Amosite/Grunerite, Crocidolite, Actinolite/Tremolite, and/or Anthophyllite) by a combination of morphology (shape and appearance), selected area electron diffraction (SAED, crystallographic structure), and energy dispersive x-ray analysis (EDXA, elemental composition). A total of 100 structures must be counted or 10 grid openings scanned, whichever is first. The analytical sensitivity is determined by the volume of the sample and the number of grid openings observed. The Limit of Detection for this method has been determined to be one confirmed asbestos structure in the total number of grid openings analysed. The results are presented by asbestos type and structure (fibre) length, i.e. structures less than 5 micrometers long (<5 µm) and structures with a length greater than or equal to 5 micrometers ( 5 µm). The total number of structures of all asbestos types present is given for each length category and the total concentration of all asbestos types of all lengths is also given. The calculated concentration of asbestos present is dependent upon the number of structures counted, the area of the filter analysed, the effective collection area of the filter and the volume of air drawn through the filter. If no asbestos structures are identified in the sample, the result is reported as being less than the Limit of Detection. Pinchin Environmental Ltd. Page 3

6 4.2 PCM Analysis PCM air samples were analysed at Pinchin Environmental s Winnipeg, Manitoba Laboratory in accordance with the National Institute of Occupational Safety and Health (NIOSH) Method 7400 dated May 15, Sample analysis was performed following the A set of counting rules. It is important to note that fibres are not identified by this method. All particles >5 µm in length and with a length to diameter ratio of 3:1 or greater are included in the count. Fibres with a diameter of <0.3 µm cannot be detected by this method regardless of length. Quality control measures taken by this laboratory follow the protocol described in the NIOSH Method The reliable quantitation limit for this method, determined from in-house quality control data, is based on a minimum fibre density of 50 fibres/mm DESCRIPTION OF WORK ACTIVITIES Two (2) maintenance staff from the Physical Plant were assigned to undertake work in the IS for the purpose of the assessment. The following maintenance activities were observed during the assessment: Working on new air conditioner; Walking around to retrieve tools; Using a Hilti Drill to simulate drilling into the metal floor and ceiling; Hammering on beams; Asbestos was scraped off the ceiling to simulate where a hole would be drilled (<0.1 sq. m.); and Pieces of asbestos were accidentally knocked off structural members when transporting tools. The work activities lasted approximately 3.5 hours. No breaks for coffee or lunch were taken during this period. The activities that the Physical Plant Department or contractors routinely carry out within the interstitial space areas have been provided in a letter from Mr. Dale Ziemanski on July 8, This is provided in Appendix IV for reference. 6.0 DISCUSSION OF AIR SAMPLING FOR ASBESTOS BY TEM AND PCM ANALYSIS 6.1 TEM Analysis In order to interpret the results of the TEM air monitoring, it is necessary to discuss the general meaning and use of air sampling. The following discussion will reference Ontario and United States guidelines or standards. No standards or guidelines based on TEM monitoring have been published by Health Canada, Manitoba Labour or other Canadian provinces. In addition, some published research information is used for comparison. Pinchin Environmental Ltd. Page 4

7 Guidelines have not yet been established specifically for asbestos air quality in general occupancy buildings. The most thorough literature review of TEM air monitoring of buildings containing Asbestos Containing Material (ACM) was published in 1991 by the Health Effects Institute (HEI) 1. Based on the results of monitoring of 198 buildings containing ACM, their report stated that the concentration of airborne asbestos fibres (longer than 5 µm) ranged from to f/ml with a mean concentration of f/ml and a 95% percentile of f/ml. Based on this, it is clear that the existence of airborne fibres longer than 5 µm, even in a building with ACM, is relatively uncommon. It should be noted however, that low levels of short (<5 µm) Chrysotile fibres are commonly found in both ambient air and in buildings with and without ACM. Although no study has provided an average for short fibres (as was provided by the HEI for fibres >5 µm) it is quite common to detect up to 3 fibres of Chrysotile asbestos in the TEM counting area of a typical air sample (with a volume collected in the order of litres). Amosite or Crocidolite asbestos is not normally detected in ambient (outdoor) or building air. In October 1987, the U.S. Environmental Protection Agency published Asbestos-Containing Materials in Schools; Final Rule and Notice. This rule is a result of the Asbestos Hazard Emergency Response Act (AHERA). Included in this rule is the requirement for post asbestos-removal (clearance) air monitoring using aggressive air sampling and analysis of the air samples by TEM for the presence of asbestos. Asbestos is identified using morphology, SAED and EDXA, and asbestos, which is longer than 0.5 µm and has an aspect ratio of 5:1 or greater is included in the results. If the average airborne asbestos concentration based on 5 samples inside the work area is higher than the equivalent of 0.02 fibre/ml, the inside airborne asbestos level must be shown to be less than the outside value. If the indoor air is shown to have a higher fibre concentration than the outside, the area is considered unacceptable for re-occupancy. Since asbestos fibres of all lengths are included, the airborne asbestos concentration of 0.02 fibre/ml is considerably more stringent than that suggested in Ontario by the MOE. It must be stressed that the AHERA method has been designed only for the clearance of asbestos removal sites where the presence of airborne asbestos is an indication of the lack of acceptable cleaning. For measurement of asbestos fibre concentrations in the outside atmosphere, to which the general public may be exposed continuously, the Ontario Ministry of the Environment (MOE) suggested a guideline of 0.04 fibre/ml (fibres longer than 5 µm) measured by TEM in the 1980 s. Therefore, only asbestos fibres are reported. In addition, the instrumental resolution is adequate to allow detection of even the very fine asbestos fibres. The origin or justification of this level has not been published for peer review. Although this guideline has never been withdrawn, more recent testing indicates that it is significantly higher than actually measured in ambient (outdoor) air. Based on all of the above studies and guidelines, it is reasonable to conclude that the asbestos content of air in a building should be considered to be elevated only when: 1 Asbestos in Public and Commercial Buildings: A Literature Review and Synthesis of Current Knowledge, Health Effects Institute-Asbestos Research, Cambridge, MA, Pinchin Environmental Ltd. Page 5

8 The average concentration of fibres >5 µm exceeds f/ml (the 95 th percentile of the HEI reported result); or More than 3 fibres (all lengths) are detected in the 10 fields analysed of a TEM sample ( L); or asbestos fibres other than Chrysotile are detected in the sample. These criteria will be used to evaluate the air samples collected. It should be noted that even if concentrations exceed these criteria they do not automatically imply an actual health risk to occupants merely an elevated level of airborne asbestos at the time of sampling. 6.2 PCM Analysis For control of airborne asbestos fibre concentrations in workplaces where asbestos is in use, Manitoba Labour currently applies a time-weighted average exposure limit of 0.1 fibre/ml (fibres longer than 5 µm) for all asbestos types. The specified measurement technique is phase contrast microscopy (PCM). In this technique, all particles are reported which are visible in phase contrast illumination at a magnification of 450, are longer than 5 µm, are less than 3 µm in width, and which have a length to width (aspect) ratio equal to or greater than 3 to 1. There is no provision for identification of specific mineral particles. All fibres whether asbestos, cellulose, fibreglass, etc., are included in the results. Under the conditions of this examination, the instrumental resolution is inadequate to allow detection of fibres having widths less than about 0.25 µm; particles longer than 5 µm will be included only if their widths are greater than this width. The detection limit varies with the sampling volume. However, the practical lower limit of quantitation is fibres per millilitre (ml), due to the common presence of other fibrous dusts at these levels. Given these limitations, this measurement technique is generally applied only where most airborne fibres are likely to be asbestos, such as in the asbestos industry or inside or immediately adjacent to asbestos abatement operations. In Manitoba, all existing legislation and environmental guidelines concerning permissible airborne asbestos fibre concentrations are expressed in terms of those fibres having lengths exceeding 5 µm. There is a general, although not universal, agreement that shorter fibres pose a lower hazard to health than long fibres. As stated by the Ontario Royal Commission on Asbestos 2 (Page 8, Chapter 1, Section B; Health Effects of Asbestos) 3. The asbestos fibres which are most likely to cause adverse health effects when inhaled are long and thin. Length and diameter are, of course, relative phenomena: fibres are measured in microns, one micron being onemillionth of a metre. The hazardous asbestos fibres are those which would be longer than 5, perhaps longer than 8 microns, and thinner than 1.5 or perhaps 0.25 microns. 2 Report of the Royal Commission on Matters of Health and Safety Arising from the Use of Asbestos in Ontario, Queens Printer for Ontario, Toronto Pinchin Environmental Ltd. Page 6

9 In the general environment, when airborne asbestos fibres are present, they are usually too small in diameter to be detected by phase contrast microscopy. In addition, in areas where asbestos is not the principal source of airborne dust, the concentration of airborne asbestos fibres is not necessarily correlated with the total fibre concentration. Particles or aggregates of particles can appear to be fibres when viewed under the conditions of the PCM examination. Conversely, features which appear in PCM to be non-fibrous particles, may actually be closely associated groups of fibres. In these circumstances, it is not possible to predict the airborne asbestos level from the result of a measurement made by PCM. 7.0 FINDINGS 7.1 Visual Observations Visual inspection of the interstitial space found settled dust and small pieces of asbestos debris dispersed throughout the area. In areas of high traffic, the spray on beams near the floor was stepped on by workers causing the spray to powder on the floor. 7.2 Background Samples Analysed by Transmission Electron Microscopy (TEM) The background samples collected in the 2 nd and 4 th Floor Corridors showed no asbestos fibres of any length to be present. The background sample collected in the 3 rd Floor Corridor was overloaded. In discussions with the analyst at EMSL Analytical, the sample was overloaded with particulate and therefore, could not be analysed to determine whether asbestos fibres are present. Two of the three background samples collected within the interstitial space showed no asbestos fibres of any length to be present. The background sample collected from the 4 th Floor interstitial space (Sample No. N 4954) found 29 Chrysotile asbestos fibres (all lengths) to be present. Of the 29 fibres, 4 were equal to or longer than 5 µm. With the exception of Sample No. N 4954, all the air samples were determined to be less than the detection limit which was s/cc or lower. The airborne asbestos concentration of Sample No. N 4954 was determined to be s/cc (all lengths) and s/cc (fibres 5 µm). Detailed sample results are provided in Appendix I. 7.3 Samples Analysed by TEM During Maintenance Activities The total number of fibres counted during maintenance activities ranged from a low of 5 fibres in the room directly below the scheduled work to a high of 60 fibres counted in the interstitial space near the new air conditioning unit. The number of structures 5 µm ranged from 1 fibre in the room directly below the scheduled work and the personal sample attached to the worker, to a high of 4 fibres counted in the interstitial space near the new air conditioning unit. The airborne concentrations for all fibres ranged from s/cc to s/cc. The concentrations for fibres 5 µm in length ranged from to s/cc of air. Detailed sample results are provided in Appendix II. Pinchin Environmental Ltd. Page 7

10 7.4 Samples Analysed by PCM During Maintenance Activities All of the air samples analysed by PCM method were below the limit of detection, which ranged from <0.01 to <0.08 s/cc. Detailed sample results are provided in Appendix III. 8.0 DISCUSSION AND CONCULSIONS This building is unique in its construction from all other buildings managed by the University of Manitoba, in that it has the interstitial space, which is sprayed with friable asbestos. This material is in very close contact to all people having to work in this area, being applied to structural members on or near the walking surfaces and at the 6-foot height. Compounding the issue is the fact that the space also serves as a return air plenum and the ceiling tiles below are perforated which allow movement of air to occupied areas. As such, any disturbance of asbestos in the interstitial space has the potential to cause elevated levels in the occupied areas below. It is difficult to confirm the source of the single elevated background sample result collected in the interstitial space. Some possible explanations include, previous activities within the area or possibly the mere access of our technician to place the sampling pump may have been sufficient disturbance. All of the remaining background samples did not detect any asbestos fibres. All of the PCM monitoring data indicate that the exposures were below both the Manitoba Labour Action Level of 0.05 s/cc and the Occupational Exposure Level 0.1 s/cc. No measurable levels above the action limit were found. All of the TEM sample results from monitoring during the exercise show elevated levels when compared to the background TEM monitoring. When considering the concentrations of fibres 5 µm in length, the results all fall below both the Manitoba Labour Action Level of 0.05 s/cc and the Occupational Exposure Level 0.1 s/cc. It is apparent that there is some low level exposure to workers when working in the interstitial space as well as low-level contamination of areas below. The primary exposure is to fibres <5 µm in length, which the Ontario Royal Commission has concluded, are the least likely to cause adverse health effects. The study concludes that precautions must be taken both to protect the workers in the interstitial space and adjacent areas. 9.0 RECOMMENDATIONS Based on our investigation we make the following recommendations: 1. Make all staff and contractors aware of the University s Asbestos Management Program; 2. Restrict access to persons following Type 2 Precautions; Pinchin Environmental Ltd. Page 8

11 3. Access should be restricted to off-hours when HVAC can be shutdown; 4. Shutdown HVAC for floor being accessed; 5. For any significant maintenance work or contracted work that has a higher potential for disturbance, isolate the rooms below by placing polyethylene to the underside of the ceiling; 6. Develop site specific procedures for any activities that do not fall within the classifications of work as established in the University of Manitoba s Asbestos Management Program; 7. Conduct air monitoring during some routine work activities to establish airborne fibre levels; and 8. Consider proactive removal of all asbestos within the facility. Don Stefanchuk Regional Manager Pinchin Environmental Ltd. Backup\Job\W Report Asbestos Risk Assessment Pinchin Environmental Ltd. Page 9

12 APPENDIX I BACKGROUND TEM AIR SAMPLES

13 APPENDIX II TEM AIR SAMPLES DURING MAINTENANCE ACTIVITIES

14 APPENDIX III PCM AIR SAMPLES DURING MAINTENANCE ACTIVITIES