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Fiber Escape from Asbestos Abatement Enclosures - Quantitative Results

Fiber Escape from Asbestos Abatement Enclosures - Quantitative Results. Paul Bozek, PEng CIH ROH Andrea Sass-Kortsak, PhD CIH ROH PO 131 Industrial Hygiene General Practice. Background - Abatement. Containment in “Type 3” Indoors:. Background - Abatement.

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Fiber Escape from Asbestos Abatement Enclosures - Quantitative Results

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  1. Fiber Escape from Asbestos Abatement Enclosures - Quantitative Results Paul Bozek, PEng CIH ROH Andrea Sass-Kortsak, PhD CIH ROH PO 131 Industrial Hygiene General Practice

  2. Background - Abatement Containment in “Type 3” Indoors:

  3. Background - Abatement • Fiber level inside removal enclosures are well known and studied • Fiber levels outside enclosures are not • Limited, published, old data suggests fiber levels outside can be elevated, depend* on • Poor worker decontamination procedures • Insufficient negative pressure inside enclosures • Problems with negative air machines/filters * Applied OEH 13(1) p 32, 1998

  4. Study Method • Observe practices /take pairs of air samples in Type 3 abatement projects (N=23) during: • Abatement (cutting, scraping, etc) • Worker decontamination at breaks • Asbestos Waste removal from enclosure • NIOSH 7400 (PCM): 20 min to 1 hour, dependent on task • Air samples are short term samples, not TWA! • Gather data on project: • # workers, pressures, type of ACM, size

  5. Study Method – Data • Assumption for “overloaded samples” • Use air volume and NIOSH 7400 max fibre density • Assumption for None detected (“ND”) • Use air volume and ½ x lab-specific fibre density LOD

  6. Results • 21 x “Type 3” Abatement Projects (Indoor) • 2 projects dropped due to short duration • 11 spray-on fireproofing • 4 plaster ceiling/wall removal (non-friable) • 5 friable ACM paper (e.g. “aircell”, sheet ) • 2 friable “magblock” plus non-friable cement • Toronto, Ontario between 2008-2011 • Some data missing (due to timing of work)

  7. Results – Observations (1) • Failure to wet ACM during abatement: N = 5 of 21 • Inadequate negative pressure: • (-5 Pa = -0.02”WG) • During Abatement , N = 8 of 21 • During Garbage removal, N = 6 of 16

  8. Results – Observations (2) Worker decontamination at breaks or end of shift: • Zero of 21 observed/reported to pre-clean suits/respirators in the “dirty room” before entering shower • None had rags/buckets of water nor HEPA vacuums placed in the “dirty room” for this purpose • Most workers took <1 minute to shower

  9. Results – Observations (3) Asbestos waste removal from shower or garbage chute: • Zero of 20 observed workers receiving waste bags wore protective suits/respirators • 8 of 20 observed to be passing out garbage bags that had not been cleaned (wet wipe or HEPA) • 6 of the 8 observed double bagging in the “dirty room” but not cleaning the outer bag

  10. Air Results: Abatement Mean: 0.65 f/cc Median 0.39 f/cc 10 overloaded Outside Enclosure Mean: 0.045 f/cc Median 0.002 f/cc 2 overloaded, 9 ND “Dirty” Room

  11. Air Samples: Worker Decontamination Task Mean: 0.20 f/cc Median: 0.03 f/cc Mean: 0.04 f/cc Median: 0.03 f/cc 3 ND “Dirty” Room 2 overload 2 ND

  12. Air Samples: Garbage Removal Task Mean: 0.26 f/cc Median 0.11 f/cc Mean: 0.013 f/cc Median: 0.008 f/cc 3 ND “Dirty” Room 6 overload 1 ND

  13. Air Samples: Univariate Analyses Few variables were truly normally distributed • Abatement pressure • Fibre count on dirty side during garbage removal Log-normal not apparent either • Too few samples? Non-parametric testing : some correlations significant, mostly relating to garbage removal

  14. Air Samples: Multivariate Analyses - Garbage Removal Fibre Count - Clean side was a function of (p<0.05) • Fibre Count (dirty side) • Number of workers in project • Negative Pressure • ACM type (non-friable, spray-on, mixed) Other models (abatement, worker decon) were not significant (p>0.05)

  15. Conclusions • Observed practices could lead to fibre escape and exposure to those in immediate vicinity of the abatement enclosures, but levels generally acceptable (with some exceptions) • 3rd party on-site consultants need to observe work practices, not just conduct milestone inspections

  16. Limitations • Short term tasks = short term sampling • Small dataset • Timing of sampling with respect to tasks variable • High variability of tasks = 21 sites representative? • Assumption for “overloaded samples” • Could be overloaded due to non-fibrous aerosols

  17. Acknowledgements Co-Investigator: Mike Russo and Enzo Garritano Infrastructure Health and Safety Assoc. of Ontario Grant Funding: Workplace Safety and Insurance Board of Ontario

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