How To Test For Residual Dust

Transcription

1 Experience on Measurement of Residual Dust as Quality Assurance Documentation During Mold Remediation AIHCE - Chicago, Illinois May 16, 2006 P. Morey & G. Crawford Boelter & Yates, Inc. Gettysburg, PA and Park Ridge, IL B. Prezant Prezant Associates Seattle, WA R. Shaughnessy University of Tulsa Tulsa, OK

2 Surface Dust Metric Gravimetric measurement of residual surface dust as a quality assurance indicator for remediation acceptance has been suggested by: ACGIH (1999) Bioaerosols; Chapter 15, Section AIHA (2001) Microbial Growth Task Force; Section 10 on Quality Assurance Principles Health Canada; Section on Particulate Cleaning

3 How Clean is Clean? When they say they are done, how do we determine if it is clean enough?

4 Residual Dust Test Origin is NADCA 1992 Standard to determine cleaning adequacy of nonporous HVAC surfaces 100 mg/m 2 standard

5 Residual Dust Test During Mold Remediation: Extends NADCA concept to all nonporous interior surfaces

6 Measuring Success Quality assurance principles of successful mold remediation (AIHA 2001) include: Moisture problem elimination. Mold removal performed according to approved protocol. Cleaning performed according to specifications.

7 Verifying Performance Quality assurance principles of successful mold remediation (AIHA 2001) include: Remediated areas checked for residual mold/water damage. HEPA vacuuming remediated space. The amount of surface dust does not indicate a need for recleaning.

8 Residual Dust - Health Canada Residual dust should be reduced as low as can reasonably be achieved. This has been defined as less than 100 mg dry weight/m 2 on smooth surfaces in a number of cognizant authority documents (ACGIH 1999; AIHA 2001.

9 White Glove/Black Glove Test If dust is visible on glove after glove is rubbed over a surface; surface needs recleaning. Too subjective! Lacks scientific basis.

10 Testing Equipment 1. Tygon tubing 2. Vacuum pump 3. 3-piece Cassette with pre-weighed PVC filter 4. Measuring tape

11 Residual Dust Collection Method 37mm filter cassette closed or open face PVC (5 µm) tared filter mini-vacuum with 5 cm flexible tubing - 45º angle on tubing inlet vacuum three (3) to ten (10) minutes, in two directions; 0.2 to 1.0 m 2 surface.

12 Residual Dust Test Example #1 - Painted Concrete Block Wall After Mold Remediation Measurement made several weeks after mold remediation. Residual dust on concrete block 10 to 15 mg/m 2 (acceptable cleaning). Rank order of indoor molds similar to molds in outdoor air.

13 Residual Dust Test Example #2 Hardwood Floor Measurement made one week after HEPA vacuuming Building unoccupied Residual dust level was 7 mg/m 2 (acceptable cleaning)

14 Residual Dust Test Example # 3 Hardwood Floor Measurement made one week after HEPA Vacuuming Building Unoccupied Residual Dust Level was 21 mg/m2 (acceptable cleaning)

15 Residual Dust Test Example #4 - Tile Floor With Semi-Porous Grout Measurement made one week after HEPA vacuuming Building unoccupied Residual dust level was 67 mg/m 2 (acceptable cleaning)

16 Residual Dust Test Example #4 -Tile Floor With Semi- Porous Grout (continued): Residual dust level was 67 mg/m 2 Concurrent inspection found extensive mold growth in nearby crawlspace with Pen-Asp levels of 10 3 to 10 4 spores/m 3 Example illustrates failure of initial inspection to identify visible mold growth

17 Inspection Issues The diagnostic and clearance inspections for visible mold, including mold hidden in building construction, must be thorough.

18 Residual Dust Test Example #5 Book Shelves Measurement made 5- days after mold remediation and HEPA vacuuming Building occupied Residual dust level was 0.2 mg/m 2 (cleaning acceptable)

19 Residual Dust Test Measurements made 1- day before and 5-days after mold remediation and HEPA vacuuming Building occupied Residual dust before cleaning = 500 mg/m 2 Residual dust after cleaning = 220 mg/m 2 Cleaning acceptable???? Example #6 Carpet

20 Residual Dust Test Measurement made 5-days after HEPA vacuum cleaning Building unoccupied Residual dust level = 40 mg/m 2 Rank order of airborne molds indoors and outdoors similar Cleaning acceptable Example #7 Return Air Grille

21 Residual Dust Test Measurement made 1 to 2 weeks after HEPA cleaning Mold remediation occurred 1 to 2 months prior Building unoccupied Non-mold demolition ongoing in building Residual dust level = 66 mg/m 2 (cleaning acceptable) Example #8 Window Sill

22 Residual Dust Test Useful Quality Assurance Indicator in Mold Remediation Simple test easily understood by cleaning personnel. Avoids interpretation difficulties associated with microbiological sampling.

23 Residual Dust Test A Useful Quality Assurance Indicator in Mold Remediation The total mass of dust has been reduced to a point that regardless of microbiologic composition, it represents a minimal exposure risk.

24 Air Sampling Is air sampling during final clearance important as a quality assurance measure in Mold remediation? In some cases, yes As in example #4 where previous inspection missed visible mold in an adjacent crawlspace Thus, air sampling will be important when inspection for mold and water damage was inadequate

25 Air Sampling Is air sampling over-emphasized as a quality assurance measure during mold remediation? Yes, in many cases such as small scale clean-ups where sampling is costly and time consuming. Results are often difficult to interpret; i.e. interference from air infiltration from other parts of the structure outside containment.

26 Too Much Reliance on Air Sampling for Final Remediation Acceptance? Philosophically, yes. The goal of mold remediation is to return interior surfaces to a satisfactory condition (AIHA 2001). Physical inspection plus residual dust measurements are more relevant to judging a satisfactory surface condition.

27 Conclusions Residual surface dust measurements should be used more frequently as a quality assurance indicator of successful mold remediation. Achieving a residual dust level on nonporous surfaces of 100 mg/m 2 appears to work well; levels of 25 mg/m 2 can often be achieved.

28 Recommendations The diagnostic inspection for hidden mold/water damage must always be excellent. The sampling protocol for residual dusts needs to be standardized. Work is needed on acceptable residual dust levels for semi-porous and porous surfaces.

29 Speaker Contact Information Philip R. Morey, PhD, CIH Director, Microbiology Boelter & Yates, Inc. 717/