The quality of the inspection is determined by the quality of the samples

192 pages of critical information

Which sampling methods are easier to interpret and which are more difficult to interpret? Why are different sampling methods needed to assess building contamination and occupant risk? Why is it better to report carpet samples on an area basis rather than a weight basis? How can sample results be converted into actionable information by using the reference, control, and database data-interpretation methods? TABLE OF CONTENTS CHAPTER 1: INTRODUCTION……………………………………………………………..1 1.0 PURPOSE………………………………………………………………………………………………………… 1 1.1 DATA QUALITY……………………………………………………………………………………………….. 3 1.2 METHOD OF COMPARISON……………………………………………………………………………. 3 1.3 BASIC CONCEPTS…………………………………………………………………………………………… 4 CHAPTER 2: TOTAL AIRBORNE FUNGAL SPORES……………………………… 16 2.0 INTRODUCTION…………………………………………………………………………………………… 17 2.1 SAMPLER SELECTION………………………………………………………………………………….. 18 2.2 SAMPLING TIME………………………………………………………………………………………….. 25 2.3 DATA INTERPRETATION METHODS……………………………………………………………. 34 CHAPTER 3: CARPET DUST SAMPLES……………………………………………… 52 3.0 INTRODUCTION………………………………………………………………………………………….. 52 3.1 COMPARISON OF SAMPLING METHODS……………………………………………………… 54 3.2 VALIDATION OF THE OPEN-FACE, FIXED AREA METHOD………………………….. 58 3.3 COMPARISON OF SAMPLING METHODS……………………………………………………… 61 CHAPTER 4: WALL CAVITY SAMPLES…………………………………………….. 66 4.0 WALL CAVITIES………………………………………………………………………………………….. 67 4.1 SAMPLING METHODS…………………………………………………………………………………. 67 4.2 COMPARISON OF SAMPLERS AND PROBES………………………………………………… 73 4.3 INTERPRETATION OF WALL CAVITY DATA………………………………………………… 79 CHAPTER 5: SOFT SURFACE SAMPLES…………………………………………… 85 5.0 INTRODUCTION…………………………………………………………………………………………. 85 5.1 SAMPLING PARAMETERS………………………………………………………………………….. .87 5.2 POST-REMEDIATION RESIDENTIAL CONTENTS……………………………………….. 87 5.3 POST-REMEDIATION OFFICE CONTENTS.. 88 5.4 SURFACE MOLD AND OCCUPANT EXPOSURE. 89 CHAPTER 6: SAMPLE ANALYSIS BY QPCR…………………………………….. 92 6.0 INTRODUCTION……………………………………………………………………………………….. 92 6.1 MICROSCOPY V. QPCR………………………………………………………………………………. 93 6.2 CARPET SAMPLES…………………………………………………………………………………….. 96 6.3 CLOTHING SAMPLES………………………………………………………………………………… 97 6.4 AIR SUPPLY DUCTS AND RETURNS………………………………………………………….. 98 6.5 PERSONAL ITEMS…………………………………………………………………………………… 100 6.6 CRITICAL CARE AREAS……………………………………………………………………………. 101 CHAPTER 7: DATA DISTRIBUTIONS AND LOG PLOTS……………………. 102 7.0 NORMAL AND LOGNORMAL DISTRIBUTIONS………………………………………… 102 7.1 CUMULATIVE PERCENT DISTRIBUTIONS……………………………………………….. 104 7.2 DATA DISTRIBUTIONS AND LOG PLOTS…………………………………………………. 106 REFERENCES………………………………………………………………………….. 114 APPENDICES APPENDIX A: AN OPINION ON ASSESSING THE HEALTH EFFECTS OF MOLD…………………………………………………………………..118 APPENDIX B: COMPARISON OF INDOOR AND OUTDOOR AIRBORNE FUNGAL SPORE CONCENTRATIONS IN RESIDENTIAL PROPERTIES……………………. 124 APPENDIX C: A COMPARISON OF SAMPLING METHOD FOR STRATIFYING CARPETS BY FUNGAL CONCENTRATION……………………………………………………… 140 APPENDIX D: A COMPARISON OF SAMPLING METHODS FOR DETECTING FUNGAL CONTAMINANTS IN CARPETS………………………………………………….. 149 APPENDIX E: Detecting Low Concentrations of Airborne Asp/Pen Spores and Aspergillus Spp. in HEPA-Filtered Hospital Air Using Microscopy and qPCR Analysiw…165   Introduction: Chapter 1 Summary The task of the IEP is not to detect mold, but rather to detect the amplification of mold in the indoor environment. There is currently little guidance as to the utility of commonly used sampling and data interpretation methods for adequately assessing condition (uncontaminated, contaminated). Sample collection presumes the ability to convert the sample results into usable information, and to use the data to differentiate between normal and amplified conditions. The selection of the sampling method and data interpretation method affects the ability of the IEP to correctly interpret the sample results and assess condition. The sampling methods discussed in this book include total airborne fungal spores, carpet dust, soft-surfaces, and wall cavities; while the data interpretation methods include the Reference Method, Control Method, and Database Method. The methods are compared based on their ability to assess condition and/or occupant exposure. A sampling method should be appropriate for the intended purpose of the investigation. For example, a sampling method may be appropriate for assessing building condition, but inappropriate for assessing occupant risk.   Airborne Samples: Chapter 2 Summary The performance of slit-impaction cassettes and filter cassettes are compared for the collection of total airborne fungal spores. The objective is not to promote the use of one sampler over another, but to inform the IEP about the characteristics of the sampler they are currently using. The four parameters affecting data quality that are discussed include sampler selection, sampling time, data-interpretation methods, and the advantages of assessing distributions rather than concentrations. Airborne samples have sometimes been characterized as not worth collecting because the results are too variable to interpret. This characterization may apply to short-term airborne samples, but may not apply to long-term samples. Short-term samples may adversely affect the ability to (1) detect a problem environment, (2) adequately assess property condition, and (3) assess occupant risk. The collection of short-term (5-10 min) samples results in a lower probability that peak concentrations will be captured, increases the probability of reporting a false negative, and may result in a poor estimate of the average concentration, which is related to occupant risk. IAQ investigators perform assessments of both property condition and occupant risk. These two broad categories of activities may require the use of different sampling methods; and a different quality of field data. Slit-impaction cassettes were adequate for assessing the condition of a property, but were less useful for assessing occupant risk. Filter cassettes were useful for assessing both condition and occupant risk. For example, the OSHA method for total airborne spores references an open-face 37 mm filter cassette loaded with a 0.8 micron MCE filter, a maximum airflow rate of 1.0 lpm, and a maximum sample volume of 120 liters. It was concluded that comparing indoor concentrations of airborne contaminant spores to outdoor concentrations has little utility. However, comparing distributions of concentrations is applicable to both contaminated and uncontaminated properties, in both commercial and residential properties. In 2005, the California Dept. of Health Services proposed requirements for establishing numerical guidelines for mold in occupied spaces. However, the document did not make a clear distinction between assessing the condition of indoor spaces versus assessing occupant exposure/risk. It was concluded that the quality of currently available data may be sufficient to establish a numerical guideline for assessing building condition, but not for assessing occupant risk.   Carpets: Chapter 3 Summary Three micro-vacuum methods for sampling carpets are compared: (1) Closed-face filter cassette with beveled-tip tubing attached; (2) Open-face filter cassette brushed across the surface of the carpet; and (3) Open-face filter cassette held firmly against discrete spots on the carpet. Reporting sample results on an area basis rather than on a weight basis provided a standardized result that better described the condition of the carpet. Since the laboratory typically sieves the carpet dust and only retains a small portion of the fine dust for analysis (typically 5 mg), weight-based results may be distorted unless reported on a total-weight basis. All three micro-vacuum methods were able to identify uncontaminated carpets using numerical guidelines. Collecting carpet samples using the OFFA method and reporting the results on an area basis was the best-performing carpet sampling method. Numerical guidelines are proposed for assessing the condition of a carpet using the open-face, fixed area sampling method. Reporting the results for micro-vacuum carpet samples (or soft-surface samples) in an ERMI format should be used with caution.   Wall Cavities: Chapter 4 Summary The Air-O-Cell, Allergenco-D, Mold Snap, and Micro-5 slit-impaction cassettes; and the Bi-Air filter cassette were compared based on sensitivity and reproducibility. The WallChek, Inner Wall, and Bi-Air sample probes were also compared using the same parameters. Their relative performance was compared based on replicate wall cavity samples collected from a test wall. Samples were collected using both quiescent and aggressive conditions. Aggressive sampling conditions resulted in substantially higher average concentrations, reduced variability between replicate samples, and a reduction in false negatives. Reporting total Asp/Pen-like spores rather than culturable fungi was a more reliable method for detecting the presence of contaminant spores; and correctly classifying the condition of the wall cavity. About half of the contaminated wall cavities included in a comparison would have been classified as uncontaminated if only culturable samples had been collected. Destructive testing combined with a visual inspection is more prone to false negatives than wall cavity sampling. It is not unusual to detect the presence of mold in a wall cavity sample, then not be able to see any visible mold on interior surfaces following destructive testing. However, it is also not unusual for swab samples collected from those same interior surfaces to be positive for indicator fungi. Numerical guidelines for wall cavity samples were proposed for the AOC-WC and the BA filter cassette.   Soft Surfaces: Chapter 5 Summary Two micro-vacuum sampling methods were assessed for sampling soft surfaces: (1) the closed-face filter cassette (CFMA) and the open-face filter cassette (OFFA) were compared based on Aspergillus-Penicillium and Cladosporium concentrations. The utility of collecting of tape lifts from soft surfaces was not assessed. A soft-surface material may be subject to surface contamination and/or deep-seated colonization. The OFFA method was capable of detecting both surface contamination and deep-seated colonization, while the CFMA method was only capable of detecting surface contamination. There was a direct relationship between the surface concentration of Asp/Pen spores and the airborne concentration of Asp/Pen-like spores.   QPCR Analysis: Chapter 6 Summary Airborne, carpet, wall cavity, and surface samples analyzed by qPCR are discussed. It may be prudent to combine microscopy with qPCR analysis whenever possible. The distributions for total Aspergillus, total Penicillium, and total fungi were presented for nine uncontaminated carpets analyzed for the 36 ERMI fungi. Ten uncontaminated items of clothing were sampled using the OFFA method, and the distributions of total Aspergillus, total Penicillium, and total fungi were reported. Concentrations of Asp + Pen spores analyzed by both microscopy and qPCR were reported for 46 airborne samples collected in critical care areas of seven hospitals. Background concentrations were less than 15 spore-equivalents/m³.   Data Distributions: Chapter 7 Summary In uncontaminated environments, the distribution of airborne mold may typically be described by a normal distribution. In contaminated environments, contaminant concentrations are better described by a lognormal distribution. The procedure for constructing a distribution of sample concentrations, and a log plot, is presented using example field data. A log plot is useful in detecting sample concentrations that exceed the maximum reportable concentration of the method (overloaded or saturated samples), making it possible to estimate the probable magnitude of the truncated data.