1 / 17

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.

amity-ramos
Télécharger la présentation

Fiber Escape from Asbestos Abatement Enclosures - Quantitative Results

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. 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

More Related