hhe report no. heta-97-0045-2676, cle elum … health hazard evaluation report 97–0045–2676 cle...

HETA 97–0045–2676Cle Elum–Roslyn High School

Cle Elum, Washington

William Daniels, CIHKenneth Martinez, MSEE, CIH

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports



This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.


applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

http://www.cdc.gov/niosh/hhe/reports



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PREFACEThe Hazard Evaluations and Technical Assistance Branch of NIOSH conducts field investigations of possiblehealth hazards in the workplace. These investigations are conducted under the authority of Section 20(a)(6)of the Occupational Safety and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary ofHealth and Human Services, following a written request from any employer or authorized representative ofemployees, to determine whether any substance normally found in the place of employment has potentiallytoxic effects in such concentrations as used or found.

The Hazard Evaluations and Technical Assistance Branch also provides, upon request, technical andconsultative assistance to Federal, State, and local agencies; labor; industry; and other groups or individualsto control occupational health hazards and to prevent related trauma and disease. Mention of company namesor products does not constitute endorsement by the National Institute for Occupational Safety and Health.

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORTThis report was prepared by William Daniels and Kenneth Martinez, of the Hazard Evaluations andTechnical Assistance Branch, Division of Surveillance, Hazard Evaluations and Field Studies (DSHEFS).Analytical support was provided by P&K Microbiology Services, Inc. Desktop publishing was performedby Nichole Herbert. Review and preparation for printing was performed by Penny Arthur.

Copies of this report have been sent to employee and management representatives at Cle Elum–Rosyln HighSchool and the OSHA Regional Office. This report is not copyrighted and may be freely reproduced. Singlecopies of this report will be available for a period of three years from the date of this report. To expediteyour request, include a self–addressed mailing label along with your written request to:

NIOSH Publications Office4676 Columbia ParkwayCincinnati, Ohio 45226

800–356–4674

After this time, copies may be purchased from the National Technical Information Service (NTIS) at5825 Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may beobtained from the NIOSH Publications Office at the Cincinnati address.

For the purpose of informing affected employees, copies of this report shall beposted by the employer in a prominent place accessible to the employees for aperiod of 30 calendar days.

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Health Hazard Evaluation Report 97–0045–2676Cle Elum–Roslyn High School

Cle Elum, WashingtonMarch 1998

William J, Daniels, CIHKenneth Martinez, MSEE, CIH

SUMMARYOn May 8, 1997, the National Institute for Occupational Safety and Health (NIOSH) received a request from theKittitas County Health Department for technical assistance in the evaluation of potential microbial contaminationin the Cle Elum–Rosyln High School, Cle Elum, Washington. A similar request had been previously received byNIOSH from employees of the school. On May 28–29,1997, NIOSH investigators conducted an initial visit to theschool. Bulk samples of building materials were collected to assess potential areas of microbial contamination andmeasurements were made of general indoor air quality comfort parameters. On September 15–16, 1997, NIOSHinvestigators conducted a follow–up evaluation during which air samples were collected for culturable fungi andspores, and measurements were repeated for general indoor air quality parameters.

Fungal concentrations from the bulk material samples ranged from none detected (ND) to 6.4x106 colony formingunits per gram of material (CFU/gm). The predominant fungi identified included Aspergillus versicolor,Chaetomium, Penicillium, Paecilomyces, Stachybotrys chartarum (a.k.a., S. atra), Rhodotorula, Sporobolomyces,and unidentified yeasts. Most of the bulk material samples revealed low concentrations of fungi that are notconsistent with the conclusion that an active microbial reservoir exists. However, seven of the twenty bulk materialsamples showed high fungal concentrations and/or were identified with significant genera. Bacterial concentrationsfrom the bulk material samples ranged from ND to 1.6x107 CFU/gm (the highest concentrations were found in ductinsulation and ceiling tiles). Gram negative bacteria were the major species detected and are normally found inassociation with large amounts of moisture. Microbiologic analysis of nine debris and dirt samples indicated fungallevels ranging from 344 to 2.6x106 CFU/gm and bacterial concentrations ranging from 1.1x104 to >5.4x107

CFU/gm (the highest concentrations were observed in the crawlspace dirt). The predominant fungal generaidentified include Acremonium, Penicillium, Cladosporium, and unidentified yeasts; the predominant bacterial typewere Gram negative species. Although in low concentrations, Aspergillus versicolor and Stachybotrys chartarum(mycotoxin producers) were identified in the crawlspace dirt.

The geometric mean of airborne fungal concentration at various locations inside the building ranged from99 colony forming units per cubic meter of air ([CFU/m3] (geometric standard deviation of 1.2) in the facultylounge to >1492 CFU/m3 (geometric standard deviation of 1.1) in the crawlspace. Acceptable levels of airbornemicroorganisms have not been established, primarily due to the varying immunogenic susceptibilities ofindividuals. Airborne dissemination [characterized by elevated levels in the complaint area, compared to outdoorand non–complaint areas, and an anomalous ranking among the microbial species] correlated to occupantsymptomatology may suggest that the contaminant may be responsible for the health effects. Outside of thebuilding, the geometric mean fungal concentration was 365 CFU/m3 (geometric standard deviation of 2.2). All of

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the indoor fungal concentrations were below the outdoor geometric mean level. The taxonomic ranking of manyof the indoor locations was dissimilar to the ranking observed outdoors. Specifically, a higher percentage ofPenicillium sp. were identified in some locations in the building. Greater relative numbers of spores were observedfor the samples collected outdoors compared with indoor sites. The most significant event observed from the sporesamples was the identification of Stachybotrys spores from the crawlspace sample. Although the relativeconcentration is low, the finding is consistent with the bulk sample results which showed the presence of culturableStachybotrys in samples collected from the exterior duct lining of an air handling unit and in the soil within thecrawlspace.

Carbon dioxide concentrations, temperatures, and relative humidity readings were generally found to be withinthose recommended by the American Society of Heating Refrigeration and Air-Conditioning Engineers(ASHRAE).

Based on the information and data obtained during this Health Hazard Evaluation, NIOSH investigatorsconclude that substantial microbial contamination existed in the crawlspace which would not make it asuitable location for placement of air handling units for the building. Recommendations related to thegeneral ventilation systems, building cleaning, and dealing with water incursion incidents are included inthe report.

Keywords: SIC 8211 (Elementary and Secondary Schools), moisture incursion, microbial contamination, fungi,spores, bacteria, Stachybotrys, Aspergillus, Penicillium, indoor air quality, ventilation

TABLE OF CONTENTS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Acknowledgments and Availability of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Initial Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Bulk Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Comfort Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Follow–up Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Air Samples for Fungi (culturable and spores) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Comfort Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Carbon Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Temperature and Relative Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Initial Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Visual Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Bulk Sample Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Comfort Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Follow–up Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Culturable Air Sample Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Comfort Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Discussion and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11D Wing Crawlspace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Building Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Water Incursion Incidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Operation and Maintenance of HVAC Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Health Hazard Evaluation Report No. 97–0045–2676

INTRODUCTIONOn May 8, 1997, the National Institute forOccupational Safety and Health (NIOSH) received aletter from the Kittitas County Health Departmentrequesting technical assistance in evaluation ofpotential microbial contamination in the CleElum–Rosyln High School, Cle Elum, Washington.A similar request had been previously received byNIOSH from employees of the school.

On May 28–29,1997, NIOSH investigators(composed of an Industrial Hygienist and anIndustrial Hygiene Engineer) conducted an initialvisit to the Cle Elum–Rosyln High School. Anopening conference was held with representatives ofthe school district, state and local health department,state labor agency, teachers, and other involvedgroups. Information was obtained related to thebuilding and the history of the concerns withmicrobiological contamination. A walk–throughinspection was made of the building exterior andinterior. Critical attention was focused on locationsidentified as water incursion points and thoseheating, ventilating, and air–conditioning (HVAC)units located in occupant–reported problem areas andin the building crawlspace. Bulk samples fromvarious building materials and crawlspace soil werecollected to assess potential areas of microbialcontamination and measurements were made ofgeneral indoor air quality comfort parameters. Aclosing conference was then held with theaforementioned representatives during whichpreliminary findings were discussed. A letter reportcontaining the sample results and recommendationswas provided to relevant personnel on August 8,1997.

On September 15–16, 1997, NIOSH investigatorsconducted a follow–up environmental evaluation atthe school. During this visit, air samples werecollected for culturable fungi and spores, andmeasurements were repeated for general indoor airquality parameters. A closing conference was heldto discuss the types of samples collected.

BACKGROUNDThe high school building was constructed inthe 1970's and currently houses approximately300 students, 19 teachers, and 11 other staff.Employee reports of health complaints began in1994. The employees reported that their healthcomplaints might be related to microbialcontamination, possibly associated with waterincursion into the building. There were reportedlytwo major episodes of water incursion, the first in1994 during a large–scale renovation of the building.Temporary roof coverings, which were being usedduring roof reconstruction, reportedly becamedisplaced allowing rain to enter portions of thebuilding. This resulted in water damage to ceilingtiles and walls. Reports from teachers indicated thatthere were areas of visible mold growth on buildingsurfaces following the leakage. The second majorinstance of moisture incursion was during the winterof 1996 – 1997 when an unusually heavy snowfallled to the formation of an “ice dam” around thebuilding. When the snow melted, water drainedtoward the school building, entering the crawlspacebelow the building. At that time, water was flowingin and along the outside air ducts for two air handlingunits located in the crawlspace below the D wing,due to the below grade location of the outside airintakes. Prior to the NIOSH visits, these two unitswere shut down and remained inoperable during theperiod of the NIOSH evaluation.

The building ventilation system consists ofcombinations of 14 central package air handlingunits (AHU), 9 unit ventilators, and 6 fin/tube(radiant heat) systems. The fin/tube units areprimarily located in the central hallways. The air inthe A and B wing classrooms is conditioned withunit ventilator systems with the exception of Room201, which is served by AHU 3. The D wingclassrooms are all served by AHUs with theexception of the Art Room which has a unitventilator. All of the systems are connected to acentral computer control system which regulates thetemperature and the amount of introduced outdoorair. All of the package AHUs are located within the

Health Hazard Evaluation Report No. 97–0045–2676 Page 3

building envelope except for AHU 12 and AHU13 which are located in the crawlspace beneath the Dwing (the units which had been shutdown). Thepackage AHUs use ducted returns with thermalinsulation located on the exterior of the duct surface.Filtration for the package AHUs consists of mediumefficiency pleated filters. The unit ventilators usedlow efficiency (less than 20%) fiber media.

METHODS

Initial Survey

Visual Inspection

A visual inspection was made of the building exteriorand interior. Critical attention was focused onspecific locations identified as water incursion pointsand those HVAC units located in occupant reportedproblem areas and in the building crawlspace.Visual inspection of interior return air duct surfaceswas facilitated with a rigid boroscope (InstrumentTechnologies, Inc., Westfield, Massachusetts).

Bulk Samples

Twenty–nine bulk material or debris samples werecollected in those locations that were suspected ofmicrobial contamination (based on visibleobservation) or those locations that provided anenvironment conducive to the growth ofmicroorganisms. Collection of 20 bulk samplesfrom interior duct insulation and floor carpet wasfacilitated by cutting an approximate one square inchsection from the material. Nine samples of debrisfrom supply air diffusers, and dirt from the D wingcrawlspace were also collected and placed into glassvials. Representative portions of each sample wereweighed and vortexed in a recorded volume of 0.2%Tween 20. Serial dilutions of the prepared sampleswere then plated to the appropriate nutrient media.The nutrient media used for fungi included maltextract agar (MEA) and cornmeal agar (CMA); thenutrient media used for bacterial cultures was trypticsoy agar (TSA). MEA and TSA are general nutrient

media used for the enumeration of fungi andbacteria, respectively. CMA is a selective media topromote the growth of Stachybotrys species.Additionally, a single “sticky” tape sample wascollected of a suspect fungal colony by using theadhesive side of the tape to pull spore structures andhyphae from the growth surface. The tape samplewas mounted (in the field) to a glass slide andsubsequently microscopically analyzed.

Comfort Indices

In addition to collecting the bulk samples formicrobial contamination, indicators of occupantcomfort were measured in each room and outdoors.These indicators were carbon dioxide (CO2),temperature, and relative humidity (RH). Real–timeCO2 concentrations were measured using aGastech Model RI–411A, portable CO2 indicator.This portable, battery–operated instrument uses anon–dispersive infrared absorption detector tomeasure CO2 in the range of 0–4975 parts permillion (ppm), with a sensitivity of ±25 ppm.Real–time temperature and humidity measurementswere made using a TSI Incorporated VelociCalcPlus, Model 8360, battery–operated air velocitymeter. This meter is capable of providing directreadings for dry–bulb temperature and RH, rangingfrom 14 to 140°F +/– 0.5°F and 20 to 95% +/– 4%,respectively.

Follow–up Survey

Air Samples for Fungi (culturableand spores)

To determine the concentrations of culturableairborne fungi, the Anderson single–stage viablecascade impactor was used at a calibrated flow rateof 28.3 liters per minute (lpm). All culturablesamples were collected over a sample time of10 minutes (with the exception of the crawlspacesamples, which were collected at 5 to 7 minuteintervals to compensate for anticipated heavierfungal loads). Malt extract agar (MEA) anddichloran glycerol agar (DG18) were used for the


enumeration of fungi (DG18 is used as the nutrientagar to select for xerophilic species). All sampleplates were incubated at room temperature(approximately 25/C). The taxa and rank of thecollected microorganisms were determined bymorphological characteristics.

Air samples for culturable fungi were collected ateight interior building locations and one outdoorlocation. Sampling locations included the ComputerLab, Room 100, Spanish (Room 102), Business(Room 300), Home and Family (Room 302),Computer Aided Design (CAD, Room 303), thefaculty lounge, and the crawlspace under the D wing.At each sample location, four replicate samples ofeach nutrient media were collected for culturablefungi (with the exception of the outdoor andcrawlspace locations where seven and five replicatesamples were collected, respectively). Samples werecollected over a two day period.

To measure the airborne concentrations of totalspores, 13 area air samples (3 of which are duplicatelocations) were collected at locations throughout thebuilding, as well as an outdoor sample location(replicated on the second day). The sample locationsincluded CAD, Computer Lab, Business, Room 100,Home and Family, Spanish, the faculty lounge, andthe crawlspace (duplicate locations included theComputer Lab, Business, and Home and Family).Spores were collected with 37 millimeter (mm)mixed cellulose ester filters. The filters were placedon cellulose support pads and sealed in plastic filtercassettes. The filter holders were connected viaTygon™ tubing to Gillian Hi Flow Sampler™battery–operated personal sampling pumps operatingat a flow rate of 2 liters per minute (lpm) over an8–hour period. Calibration of the flow rates wasperformed immediately prior to, and after, sampling.For subsequent calculation of sample volumes, themean of the pre– and post– sampling flow rates wasused. Calibration of the pumps on–site wasaccomplished with a rotometer, which in turn wascalibrated with a primary standard (bubbleflowmeter) prior to the evaluation. Samples wereanalyzed for fungal spore counts by opticalmicroscopy. Filters were cleared with acetone vapor,

mounted in cotton blue/lactic acid, and scanned at400x magnification with bright field or phasecontrast illumination. Two hundred fields werecounted for each sample. Only particles greater than2 :m in diameter were considered to be possiblefungal spores.

Comfort Indices

In addition to collecting air samples, indicators ofoccupant comfort were measured in each of therooms of the building and outdoors. These indicatorswere CO2 concentration, temperature, and RH, andwere collected in accordance with the methods usedduring the initial survey.

EVALUATION CRITERIANIOSH investigators have completed over1,200 investigations of the occupational indoorenvironment in a wide variety of non–industrialsettings. Almost all of these investigations have beenconducted since 1979.

The symptoms and health complaints reported toNIOSH by building occupants have been diverse andusually not suggestive of any particular medicaldiagnosis or readily associated with a causativeagent. A typical spectrum of symptoms has includedheadaches, unusual fatigue, varying degrees ofitching or burning eyes, irritations of the skin, nasalcongestion, dry or irritated throats, and otherrespiratory irritations. Typically, the workplaceenvironment has been implicated because workersreport that their symptoms lessen or resolve whenthey leave the building.

A number of published studies have reported a highprevalence of symptoms among occupants of officebuildings.1,2,3,4,5 Scientists investigating indoorenvironmental problems believe that there aremultiple factors contributing to building–relatedoccupant complaints.6,7 Among these factorsare imprecisely–defined characteristics of HVACsystems, cumulative effects of exposure to lowconcentrations of multiple chemical pollutants,


odors, elevated concentrations of particulate matter,microbiological contamination, and physical factorssuch as thermal comfort, lighting, and noise.8,9,10,11,12,13

Indoor environmental pollutants can arise fromeither outdoor sources or indoor sources.

There are also reports describing results which showthat occupant perceptions of the indoor environmentare more closely related to the occurrence ofsymptoms than any measured indoor contaminant orcondition.14,15,16 Some studies have shownrelationships between psychological, social, andorganizational factors in the workplace andthe occurrence of symptoms and comfortcomplaints.16,17,18,19

Less often, an illness may be found to be specificallyrelated to something in the building environment.Some examples of potentially building–relatedillnesses are allergic rhinitis, allergic asthma,hypersensitivity pneumonitis, Legionnaires' disease,Pontiac fever, carbon monoxide poisoning, andreaction to boiler corrosion inhibitors. The first threeconditions can be caused by various microorganismsor other organic material. Legionnaires' disease andPontiac fever are caused by Legionella bacteria.Sources of carbon monoxide include vehicle exhaustand inadequately–ventilated kerosene heaters orother fuel–burning appliances. Exposure to boileradditives can occur if boiler steam is used forhumidification or is released by accident.

Problems that NIOSH investigators have found in thenon–industrial indoor environment have includedthe following: poor air quality due to ventilationsystem deficiencies, overcrowding, volatile organicchemicals from furnishings, emissions from officemachines, structural components of the buildingand contents, tobacco smoke, microbiologicalcontamination, and outside air pollutants; comfortproblems due to improper temperature and RHconditions, poor lighting, and unacceptable noiselevels; adverse ergonomic conditions; andjob–related psychosocial stressors. In most cases,however, these problems could not be directly linkedto the reported health effects.

Standards specific for the non–industrial indoorenvironment do not exist. NIOSH, the OccupationalSafety and Health Administration (OSHA), and theAmerican Conference of Governmental IndustrialHygienists (ACGIH®) have published regulatorystandards or recommended limits for occupationalexposures.20,21,22 With few exceptions, pollutantconcentrations observed in non–industrial indoorenvironments fall well below these publishedoccupational standards or recommended exposurelimits. American Society of Heating Refrigerationand Air–Conditioning Engineers (ASHRAE) haspublished recommended building ventilation designcriteria and thermal comfort guidelines.23,24 TheACGIH has also developed a manual of guidelinesfor approaching investigations of building–relatedcomplaints that might be caused by airborne livingorganisms or their effluents.25

Measurement of indoor environmental contaminantshas rarely proved to be helpful in determining thecause of symptoms and complaints except wherethere are strong or unusual sources, or a provenrelationship between contaminants and specificbuilding–related illnesses. The low–levelconcentrations of particles and variable mixtures oforganic materials usually found are difficult tointerpret and usually impossible to causally link toobserved and reported health symptoms. However,measuring ventilation and comfort indicators such asCO2, temperature, and RH, has proven useful in theearly stages of an investigation in providinginformation relative to the proper functioning andcontrol of HVAC systems.

NIOSH and the Environmental Protection Agency(EPA) jointly published a manual on building airquality, written to help prevent environmentalproblems in buildings and solve problems whenthey occur.26 This manual suggests that indoorenvironmental quality (IEQ) is a constantly changinginteraction of a complex set of factors. Four of themost important elements involved in thedevelopment of IEQ problems are: (1) a source ofodors or contaminants; (2) a problem with the designor operation of the HVAC system; (3) a pathwaybetween the contaminant source and the location of


the complaint; and (4) the building occupants. Abasic understanding of these factors is critical topreventing, investigating, and resolving IEQproblems.

The basis for measurements made during thisevaluation are listed below.

MicroorganismsMicroorganisms (including fungi and bacteria) arenormal inhabitants of the environment. Thesaprophytic varieties (those utilizing non–livingorganic matter as a food source) inhabit soil,vegetation, water, or any reservoir that can providean adequate supply of a nutrient substrate. Under theappropriate conditions (optimum temperature, pH,and with sufficient moisture and available nutrients)saprophytic microorganism populations can beamplified. Through various mechanisms, theseorganisms can then be disseminated as individualcells or in association with soil or dust particles orwater droplets. In the outdoor environment, thelevels of microbial aerosols will vary according tothe geographic location, climatic conditions, andsurrounding activity. In a "normal" indoorenvironment, where there is no unusual source ofmicroorganisms, the level of microorganisms mayvary somewhat as a function of the cleanliness of theHVAC system and the numbers and activity level ofthe occupants. Generally, the indoor levels areexpected to be below the outdoor levels (dependingon HVAC system filter efficiency) with consistentlysimilar ranking among the microbial species.27,28

Some individuals manifest increased immunologicresponses to antigenic agents encountered in theenvironment. These responses and the subsequentexpression of allergic disease is based, partly, on agenetic predisposition.29 Allergic diseases whichhave been reported to be associated with exposuresin indoor environments include allergic rhinitis(nasal allergy), allergic asthma, allergicbronchopulmonary aspergillosis (ABPA), andextrinsic allergic alveolitis (hypersensitivitypneumonitis).27 Allergic respiratory diseasesresulting from exposures to microbial agents have

been documented in agricultural, biotechnology,office, and home environments.30,31,32,33,34,35,36,37

Symptoms vary with the type of allergic disease:(1) allergic rhinitis is characterized by episodes ofsneezing, itching of the nose, eyes, palate, orpharynx, nasal stuffiness with partial or total airflowobstruction, and rhinorrhea with postnasal drainage;(2) allergic asthma is characterized by episodic orprolonged wheezing and shortness of breath due tobronchial narrowing; (3) ABPA is characterized bythe production of IgE and IgG antibodies withsymptoms of cough (which is sometimes productiveof mucous), fatigue, low grade fever, andwheezing.27,38 Heavy exposures to airbornemicroorganisms can result in an acute form ofextrinsic allergic alveolitis which is characterized bychills, fever, malaise, cough, and dyspnea (shortnessof breath) appearing 4 to 8 hours after exposure.Onset of the chronic form of extrinsic allergicalveolitis is thought to be induced by a continuouslow–level exposure, and onset occurs without chills,fever, or malaise, but is characterized by progressiveshortness of breath with weight loss.39 However,despite these relatively well–defined diseases whichhave been reported to occur in office environments,as described previously, symptoms most commonlyencountered by office workers are generally notassociated with any particular medical diagnosis oretiologic agent.

Acceptable levels of airborne microorganisms havenot been established, primarily due to the varyingimmunogenic susceptibilities of individuals.Relationships between health effects andenvironmental microorganisms must be determinedthrough the combined contributions of medical,epidemiologic, and environmental evaluation.25 Thecurrent strategy for on–site evaluation involves acomprehensive inspection of problem areas toidentify sources of microbial contamination androutes of dissemination. In those locations wherecontamination is visibly evident or suspected, bulksamples may be collected to identify the predominantspecies (fungi, bacteria, and thermoactinomycetes).In limited situations, air samples for microorganismsmay be collected to document the airborne presence


of a suspected microbial contaminant. Airbornedissemination (characterized by elevated levels in thecomplaint area, compared to outdoor andnon–complaint areas, and an anomalous rankingamong the microbial species) correlated to occupantsymptomatology may suggest that the contaminantmay be responsible for the health effects.

Carbon DioxideCarbon dioxide is a normal constituent of exhaledbreath and, if monitored, can be used as a screeningtechnique to evaluate whether adequate quantities ofoutside air are being introduced into an occupiedspace. ASHRAE's most recently publishedventilation standard, ASHRAE 62–1989, Ventilationfor Acceptable Indoor Air Quality, recommendsoutdoor air supply rates of 20 cubic feet per minuteper person (cfm/person) for office spaces, and15 cfm/person for reception areas, classrooms,libraries, auditoriums, and corridors. Maintainingthe recommended ASHRAE outdoor air supply rateswhen the outdoor air is of good quality, and there areno significant indoor emission sources, shouldprovide for acceptable indoor air quality.

Indoor CO2 concentrations are normally higherthan the generally constant ambient CO2concentration (range 300–350 ppm). Carbon dioxideconcentration is used as an indicator of the adequacyof outside air supplied to occupied areas. ASHRAEStandard 62–1989 recommends 1000 ppm as theupper limit for comfort (odor) reasons.23 Whenindoor CO2 concentrations exceed 800 ppm in areaswhere the only known source is exhaled breath,inadequate ventilation is suspected.40 Elevated CO2concentrations suggest that other indoorcontaminants may also be increased. It is importantto note that CO2 is not an effective indicator ofventilation adequacy if the ventilated area is notoccupied at its usual level.

Temperature and RelativeHumidityTemperature and RH measurements are oftencollected as part of an indoor environmental qualityinvestigation because these parameters affect theperception of comfort in an indoor environment. Theperception of thermal comfort is related to one'smetabolic heat production, the transfer of heat to theenvironment, physiological adjustments, and bodytemperatures.41 Heat transfer from the body to theenvironment is influenced by factors such astemperature, humidity, air movement, personalactivities, and clothing. The ASHRAE Standard55–1992, specifies conditions in which 80% or moreof the occupants would be expected to find theenvironment thermally comfortable.24 ASHRAEalso recommends that RH be maintained between30 and 60% RH. Excessive humidities can supportthe growth of microorganisms, some of which maybe pathogenic or allergenic.

RESULTS

Initial Survey

Visual Inspections

Inspection of various HVAC units housed inside ofthe building envelope did not reveal environmentalconditions supportive of fungal growth and,subsequently, obvious fungal contamination. Theinteriors of the inspected systems’ workingcomponents appeared dry and clean. However, theinsulation lining of the return air ducts located ineach of the serviced classrooms exhibitedconsiderable debris (i.e., dust agglomerated to theduct lining and trash deposited in the plenum). Incontrast, the AHUs located beneath the D wingcrawlspace (AHU 12 and 13) showed evidence offlooding into the outdoor air supply ducts. Theflooding was evidenced by the residual water line inthe duct interior and water remnants bound into thefibers of the exterior duct lining.


During the walk–through investigation, active fungalgrowth was observed in only a few locations insidethe building. Significant growth was observed in theHome and Family classroom at the return air diffuserbeneath the linoleum floor. Reports from the facultyindicated that the floor of this room was floodedrecently due to a burst water pipe. Bubbles in thelinoleum were observed by the NIOSH investigators,likely a direct result of water incursion. Fungalcolonies were also observed on ceiling tiles that hadbeen left in the attic space above some of theclassrooms. These tiles had reportedly beenremoved earlier in the year as a result of waterdamage from a leaking roof, but some of the tiles stillremained scattered along the top of the ductwork.Although the crawlspace underneath the D wing hada musty odor, there was no visible evidence of activefungal growth. However, occupants stated that thedirt floor had recently been raked. Active groundwater incursion into the crawlspace was observed atvarious points in the foundation. In addition, aplastic sheet was observed below the dirt floor. This“vapor barrier” will result in the inability of water todrain out of the crawlspace. The pooling created bywater intrusion into the crawlspace and the dirt floormake the likelihood of fungal growth at variouslocations within the crawlspace highly probable.

Bulk Sample Analysis

Fungal concentrations from the bulk materialsamples ranged from non–detectable (ND) to 6.4x106

colony forming units per gram of material (CFU/gm)and are summarized in Table 1. The predominantfungi identified included Aspergillus versicolor,Chaetomium, Penicillium, Paecilomyces,Stachybotrys chartarum (a.k.a. S. atra), Rhodotorula,Sporobolomyces, and unidentified yeasts. Thesegenera have been implicated as allergens andAspergillus, Penicillium, and Stachybotryschartarum have been additionally noted asmycotoxin producers. Chaetomium, Stachybotryschartarum, Rhodotorula, Sporobolomyces, andunidentified yeasts are characterized as hydrophilic(moisture–loving) fungi. Most of the bulk materialsamples revealed low concentrations of fungi whichis not consistent with the existence of an active

microbial reservoir. However, 7 of 20 bulk materialsamples resulted in high fungal concentrations and/orwere identified with significant genera.

The wood floor sample collected from the Home andFamily classroom had concentrations of Aspergillusversicolor and Chaetomium ranging to 1.4x106 and1.8x106 CFU/gm, respectively. This is consistentwith the sticky tape sample from the flooring thatalso revealed predominantly Aspergillus sp. andChaetomium. Additionally, bulk material samplesfrom the lining of the two return air duct plenums inthe Home and Family Life classroom revealedAspergillus sp. and Chaetomium, although in lowconcentrations. Bulk material samples collectedfrom the exterior thermal insulation of the outdoorair intake of AHU 12 revealed high concentrations ofGram negative and Gram positive bacteria(3.3x106 and 2.4x107 CFU/gm, respectively) andconcentrations of Stachybotrys chartarum ranging upto 7.7x105 CFU/gm. A bulk material samplecollected from the interior duct lining of AHU13 (before the filters) revealed the presence of a lowconcentration of Stachybotrys chartarum(769 CFU/gm) and, additionally, Penicillium rangingto 1.6x104 CFU/gm. Bulk material samples fromtwo ceiling tiles found in the attic space above theschool were cultured with fungal concentrationsranging up to 4.7x106 CFU/gm; the predominantgenera identified included Rhodotorula, unidentifiedyeasts, Penicillium, and Sporobolomyces.

Bacterial concentrations from the bulk materialsamples ranged from ND to 1.6x107 CFU/gm. Gramnegative bacteria were the major type detected andare normally found in association with large amountsof moisture. The highest bacterial concentrationswere found in the floor sample from the Home andFamily Life classroom, in both of the outdoor airintake exterior thermal insulation samples collectedfrom AHU 12, and in the ceiling tile samples.

Microbiologic analysis of the nine debris and dirtsamples indicated fungal levels ranging from 344 to2.6x106 CFU/gm and bacterial concentrationsranging from 1.1x104 to >5.4x107 CFU/gm (Table 2).The predominant fungal genera identified include


Acremonium, Penicillium, Cladosporium, andunidentified yeasts; the predominant bacterial typewas Gram negative. Significant concentrations(greater than 1x106 CFU/gm) of fungi or bacteriawere found in the dirt samples collected in theD wing crawlspace (under Room 302 andunder the AHU 12 outdoor air intake). Moderateconcentrations (greater than 1x104 CFU/gm) of fungiand bacteria were detected in all remaining samples(including the supply air diffuser debris in theBusiness classroom) except those collected from thewater dampened areas of the crawlspace dirt and thepooled water in the AHU 12 exterior duct lining.However, the lack of fungal growth from theexception samples is not unusual as fungi do nottolerate low oxygen levels in water saturatedenvironments. Although in low concentrations,Aspergillus versicolor and Stachybotrys chartarum(mycotoxin producers) were identified in thecrawlspace dirt.

Comfort Indices

Carbon dioxide concentrations ranged from 300 to1225 ppm in the 21 locations measured in thebuilding. The mean concentration was 520 ppm.Two measurements, 1200 ppm in Room 104 and1225 ppm in Room 100, exceeded the 1000 ppmrecommended in the ASHRAE Standard 62–1989 asthe upper limit for comfort (odor) reasons. Theoutdoor air CO2 concentration was 300 ppm.

Temperatures in the building ranged from 68° to76°F, with a mean of 71°F. Relative humidityranged from 53% to 60%, with a mean of 56%.These measurements were within the comfort zonerecommended in ASHRAE Standard 55–1982;however, the combination of temperature and RHmight feel somewhat cool to those in summertimeclothing.

Follow–up Survey

Visual Inspection

During the follow–up survey, some moistureincursion was noted in the D wing crawlspace,primarily through pipe and conduit entries throughthe foundation. During a period of rain during thesurvey, water drained into the below groundlocations where the air intakes for AHUs 12 and13 are located. It should be noted that these twoAHUs were still not being operated, and ventilationto the D wing classrooms was supplied through opendoors or windows.

Two additional areas identified during the initialsurvey as potential reservoirs for microbiologicalcontamination appeared to have been eliminated.The ceiling tiles had been removed from the atticspaces above the classrooms, and the remaining tilesabove the kitchen area had reportedly been inspectedand no microbial growth was found. The linoleum,underlayment, and parts of the subfloor in the Homeand Family classroom had been removed andreplaced; however, some employee reports indicatedthat no containment procedures were used during thisprocedure. No additional microbial reservoirs werenoted during this survey.

Culturable Air Sample Analysis

A graphical summary of the bioaerosol samplingresults for fungi is presented in Figure 1. Nosignificant differences existed in concentration or thepredominant taxa between the different nutrientmedia (MEA and DG18) at each of the varioussampling locations; therefore, the data collectedusing different nutrient media at each location waspooled. The geometric mean fungal concentration atvarious locations inside the building ranged from99 colony forming units per cubic meter of air([CFU/m3] geometric standard deviation of 1.2) inthe faculty lounge to >1492 CFU/m3 (geometricstandard deviation of 1.1) in the crawlspace. Due toovergrowth on the culture plates collected in thecrawlspace, the concentration is an estimate that


assumes a CFU under every impaction hole. Outsideof the building, the geometric mean fungalconcentration was 365 CFU/m3 (geometric standarddeviation of 2.2). All of the indoor fungalconcentrations were below the outdoor geometricmean level, however, the concentrations in four ofthe classrooms (i.e., Spanish, Business, Home andFamily, and CAD) approached the outdoorconcentration.

The taxonomic ranking (i.e., the ranking of thepredominant genera according to frequencyoccurrence) of many of the indoor locations wasdissimilar to the ranking observed outdoors.Specifically, a higher percentage of Penicillium sp.(indicated by the line with the square markers inFigure 1) was identified in the Computer Lab,Room 100, Spanish, Home and Family, CAD,and the faculty lounge. Outdoors, the percentage ofPenicillium averaged 14%, whereas indoors, in theaforementioned locations the percentages rangedfrom 27% to 44%. Aspergillus sp. (indicated by thecircles in Figure 1) were also identified in theComputer Lab, Room 100, Spanish, Home andFamily, and CAD. The percentages of Aspergillusspecies identified were low by comparison; however,no Aspergillus species were identified outdoors.

The results of air sampling for total spores are shownin Table 3. The spore concentrations should only beused as qualitative indicators of spore levels at eachlocation, due to problems encountered with thesampling method (i.e., sampling closed face) thatmay have resulted in an under–estimation of the totalspore count. Like the culturable sampling results,greater relative numbers were observed for thesamples collected outdoors compared with indoorsites. The most significant event observed from thespore samples was the identification of Stachybotrysspores from the crawlspace sample. Although therelative concentration is low, the finding isconsistent with the bulk sample results which showthe presence of culturable Stachybotrys in samplescollected from the exterior duct lining of AHU13 and in the soil within the crawlspace.

Comfort Indices

Carbon dioxide concentrations ranged from 425 ppmto 1150 ppm, with a mean concentration of 650 ppmin the 13 samples. Two measurements (Rooms100 and 104) exceeded the 1000 ppm recommendedin the ASHRAE Standard 62–1989 as the upperlimit for comfort (odor) reasons. In both instances,classrooms were occupied by 20 or more students.The outdoor air CO2 concentration was 350 ppmduring the follow–up survey.

During the follow–up survey, temperatures in thebuilding ranged from 67° to 71°F, with a mean of69°F, and RH ranged from 53% to 59%, with a meanof 56%. These measurements were within thecomfort zone recommended in ASHRAE Standard55–1982; however; the combination of temperatureand RH might feel somewhat cool to those insummertime clothing.

DISCUSSION ANDCONCLUSIONS

The growth and survival of microorganisms inenvironmental reservoirs requires (a) a suitablenutrient source; (b) adequate available water; and(c) an appropriate temperature. These factors are alldetermined by the localized environment and whencombined with high porosity materials, can provideoptimum conditions for microorganisms to grow. Inthe crawlspace under the D wing, these factors wereall present; i.e., water intrusion from snow melt andrain storms (present in the duct lining and in the dirtfloor), organic material in the dirt floor, and cooltemperatures (that result in increased humidity).Microbial contamination was confirmed by bulksample analysis in select locations of the dirt floorand from exterior lining in the outdoor air intakes ofthe AHUs. Some of the fungal species identifiedincluded the mycotoxin producers Aspergillusversicolor and Stachybotrys chartarum. Theculturable air sample results showed the existence oflarge concentrations of fungal species (as evidencedby the overgrowth for short sampling times) which


included Aspergillus and Penicillium species. Theselarge concentrations demonstrate the activedissemination of fungal reservoirs in the crawlspace.The upstream side of the fan in AHUs operate undera negative static pressure. Placement of the AHUs inthe crawlspace will inevitably draw air andcontaminants from the crawlspace (andcontaminants in the exterior duct insulation) into thesystem to be disseminated to the occupied spaces.Therefore, a potential pathway exists for thedissemination of microbial contaminants into the airspaces supplied by these AHUs. This clearlyindicates that this is not a suitable location for theAHUs. It would also indicate a need to keep thebuilding areas under a positive pressure, with respectto this space, to prevent entrainment of microbialcontamination into the classrooms.

Growth conditions were also present in the Homeand Family classroom as evidenced by the“bubbling” of the linoleum floor noted during theinitial survey visit, and subsequent growth ofAspergillus versicolor and Chaetomium in thewood underlayment. However, the microbialcontamination in this classroom should beconsidered as localized given that a substantialpathway to the occupied areas is not present exceptat the flooring seams. However, bulk materialsample analysis of the return air plenum revealedevidence of small numbers of Aspergillus versicolorand Chaetomium spores and/or hyphae in the interiorthermal insulation. This would seemingly indicatethat some dissemination of the microbialcontaminants was occurring from the woodunderlayment. Although the linoleum floor had beenreplaced by the September 1997 follow–up visit, theobserved fungal concentrations (as shown by theculturable air sample results) were among the highestobserved in the school. In addition, the contributionby Penicillium species to the total fungal load wasthe highest percentage (approximately 44%)compared to all other sample locations. These levelsmay not necessarily be indicative of currentreservoirs, but rather an indication of inappropriate(or non–existent) containment during (andinadequate cleaning after) the removal of the oldlinoleum floor and the installation of the new floor.

A more thorough cleaning of this area appearswarranted.

The bulk samples and visual observation did notreveal the existence of substantial microbialreservoirs in the other areas of the school at the timeof the site visits. Furthermore, no evidence ofongoing moisture incursion or moist conditions wasnoted, which is needed for ongoing growth ofmicrobial contaminants. Since separate air handlingsystems supply the different areas of the school, nocommon dissemination pathway would be expectedto exist from those areas of the school wheremicrobial reservoirs were noted. This would tend tobe supported by the culturable air and spore sampleresults which indicated all of the indoor fungalconcentrations were below the outdoor level. Thedissimilarities found in the taxonomic ranking ofmany of the indoor locations is somewhat moredifficult to interpret. The higher levels ofPenicillium sp. identified in some locations may beindicative of a small residual from pastcontamination (such as during the remodeling orincidents of flooding) or dissemination (from theAHUs in the D wing crawlspace) with ineffectivecleanup. However, this conclusion is speculativebased on the inherent limitations of this type of data.Due to the high level of concern, and the fact that apotential for microbial contamination existed fromthe previously described events, it would seemprudent to make all reasonable efforts to thoroughlyclean these areas to remove any doubt of residualcontamination.

RECOMMENDATIONS

D Wing CrawlspaceThe crawlspace should not be used as a location forAHUs and/or associated negative pressureductwork. Unit ventilators located in the classroomsor centrally located AHUs should be used to provideair to these building. The ventilation system(s) in theD wing should be operated in a manner so as to keepthe occupied building spaces at a positive pressurewith respect to the crawlspace. The use of an


additional exhaust fan(s) in the crawlspace may helpinsure this pressure differential.

Building CleaningVisible or suspected microbial contaminationrequires remediation efforts including the removal ofthe contaminated material and/or clean–up with ahigh efficiency particulate air filter (HEPA) vacuumand decontamination with an effective chemicalagent (i.e., 5 to 10% solution of chlorine bleach).Remediation will result in the disruptionof microbiological reservoirs. The airbornedissemination of these bioaerosols can pose asignificant exposure concern for the remediationworkers. Additionally, these aerosols can be spreadto uncontaminated areas of a building, increasing thehazard for the remaining occupants and adding to thedifficulty of clean–up. Therefore, it is important thatall remediation activities be conducted with anawareness of the potential bioaerosol exposures andwith minimal disturbance of contaminated materials.Specifically, controls must be instituted that protectboth the worker and the adjacent environment.

Remediation workers should use personal protectiveequipment (PPE) appropriate for the hazards towhich they may be exposed. Such decisions requirea priori awareness of potentially hazardous agents,significant exposure routes (e.g., inhalation, dermalcontact, or ingestion), and possible concentrations ofthe biological materials. Remediation work onsmall, localized patches of mold growth on ceilingsor walls should be conducted with appropriaterespirators (i.e., a disposable N–95NIOSH–approved respirator with a facepiece that fitstightly, ensuring that contaminants do not enterthrough leaks between the respirator and a wearer'sface), eye protection, and gloves. However,situations involving gross contamination withmicroorganisms that pose potentially significanthealth outcomes (e.g., infectious or toxigenic fungi),may require a higher level of PPE due to theconcentrations of the microbial agents and theirdisease potential (e.g., full–face, poweredair–purifying respirators, disposable protectiveclothing with hoods, gloves, and disposable shoe

coverings). For respirator use, OSHA requires arespiratory protection program that includes thefollowing components: written standard operatingprocedures, user instruction and training, cleaningand disinfection, storage, inspection, surveillance ofwork area conditions, evaluation of respiratorprotection program, medical review, and use ofcertified respirators.42

Given the level of disruption that may occur duringmicrobiological remediation work, engineeringcontrols applied at the source should be the primarycontrol measure. Remediation activities should beconducted in a manner that minimizes thedisturbance of microbiological reservoirs. However,as the extent of the microbial contamination becomeslarger, reservoir dissemination becomes unavoidabledue to the activities of surrounding building materialremoval. Under these conditions, isolation barriersare required to contain airborne spores andother biological matter. Barriers alone disrupt thepathways between remediation zones and adjacentenvironments, but disseminated aerosols almostinvariably find breaks in any barrier system.Therefore, negative pressure relative to adjacentareas is induced in the remediation zone to ensurecontainment. It is critical that the exhausted airstreams be appropriately filtered (i.e., HEPA filters)to guard against the re–entry of microbiallycontaminated air back into the zone of remediationand/or to other areas that are considereduncontaminated. Specific control guidelines havebeen recommended for the remediation of toxigenicfungi from contaminated materials.43

Water Incursion IncidentsAny episodes of water incursion should be dealt withpromptly. Water should be removed immediatelyfrom porous, water damaged furnishings, carpets,and construction materials. Heat fans should be usedto dry carpets and other applicable surfaces within24 hours. Steam or other water–based cleaningmethods which add moisture to the environmentmust be used with extreme care. Any soft materialsthat become wet with sewage contaminated watershould be promptly discarded. A written program


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Operation and Maintenanceof HVAC SystemsContinuing attention should be given to ensuring thecomfort of the building occupants through regulationof temperature (in consideration of the RH) and thesupply of adequate amounts of outside air to theoccupied spaces. Written logs of unit inspectionsand filter changes should be maintained. Return airducts in the classrooms should be regularly inspectedand dirt and debris removed as needed.

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Table 1. Microbiological Results of Bulk Samples

Sample LocationFungi (CMA) Fungi (MEA) Bacteria (TSA)

(CFU/gm) Taxa Rank (CFU/gm) Taxa Rank (CFU/gm) Taxa RankB1 (Home and Family – under linoluem) 4.1x106 Chae>Pen>A. ver 3.4x106 A. ver>Pen>Chae 1.6x107 G negB2 (Room 301 – return duct insulation) ND ND 752 unidentifiedB3 (Home and Family – return duct insulation 1) 1.5x103 Chae>Pen>A. ver=

Pen= Clad3.5x103 Chae ND

B4 (Home and Family – return duct insulation 2) 4.0x103 Pen>Clad 6.5x103 Pen>Cha=Y 806 unidentifiedB5 (Room 300 – return duct insulation) 1.7x103 Pen=Pae 1.7x103 Pen>stf>Pae 1.7x103 unidentifiedB6 (Room 103 – unit ventilator insulation) 813 Y ND NDB7 (Room 200 – unit ventilator insulation) 4.0x103 Pen>Clad>Chae 16,200 Pen>>Clad 1.0x103 unidentifiedB8 (AHU 12 – exterior insulation below fan) 9.5x103 Y=Clad>Chae 4.8x103 Pen>Epi=Clad=Chae 1.8x104 G neg>BacB9 (AHU 12 – outside air intake exterior insulation 1) 5.8x105 Sta>>Y=Dor 8.7x105 Sta>>Pho>A. Fum=

stf=Y3.3x106 G neg

B10 (AHU 12 – outside air intake exterior insulation 2) 2.1x103 Y=Aur>Tri 592 Pen=Tri >2.4x107 unidentifiedB11 (AHU 12 – interior insulation) 7.3x103 Clad>Pen>Asp 7.3x103 stf>Clad=Y>Pen 6.1x104 G neg>BacB12 (AHU 12 – interior insulation 1) 2.1x104 Pen>>Y>Clad>stf=Sta 1.8x104 Pen>>A. nig=Clad>Ulo 3.0x104 G neg>Bac>Mic=

RhoB13 (AHU 12 – interior insulation 2) 4.7x103 Pen>Clad=stf 3.7x103 Pen 1.7x104 G negB14 (Room 100 – unit ventilator insulation) ND 3.3x103 Clad=Pen=Pith=Y 3.3x103 unidentifiedB15 (AHU 1 – interior insulation 1) 4.2x103 Pen>stf 5.8x103 Pen>Clad 4.2x103 unidentifiedB16 (AHU 1 – interior insulation 2) ND 855 Pen 7.7x103 G negB17 (Room 100 – carpet) 909 Pen 909 Pen=Acr 455 unidentifiedB18 (ASB room – carpet) 8.7x103 Pen>Y 8.7x103 Pen>Y 3.9x104 G negB19 (Ceiling tile 1) 3.4x106 Y>Rho>>Spo>Aur=

Chry=Pen3.2x106 Y>Rho>>Spo>Aur=Pen 2.3x105 G neg>Bac

B20 (Ceiling tile 2) 6.4x106 Y>>Spo>Pen>Chry>Rho 3.6x106 Y>>Spo>Pen>Chry=Rho 1.8x106 G neg>Bac

Acr – Acremonium Dora – Doratomyces Spo – Sporobolomyces Bac – BacillusA ver – Aspergillus versicolor Epi – Epicoccum nigrum Sta – Stachybotrys chartarum G neg – Gram negativeA nig – Aspergillus niger Pae – Paecilolmyce3s variotii stf – sterile fungi Mic – MicrococcusAur – Aureobasidium pullulans Pen – Penicillium Tri – Trichoderma Rho – RhodococcusChae – Chaetomium Pho – Phoma Ulo – Ulocladium charatarumChry – Chrysoprorium Pith – Pithomyces Y – unidentified yeastClad – Cladosporium Rho – Rhodotorula


Table 2. Microbiological Results of Bulk Samples (debris and dirt)

Sample LocationFungi (CMA) Fungi (MEA) Bacteria (TSA)

(CFU/gm) Taxa Rank (CFU/gm) Taxa Rank (CFU/gm) Taxa RankV1 (crawlspace soil under Room 302) 2.6x106 Acr >Pen>>A. ver=Clad 2.1x106 Pen>Acr>>Tri>Clad >5.4x107 G neg

V2 (crawlspace soil 1 under AHU 12) 4.2x103 Pen>Mon=Pho=Sta=Tri 4.2x103 Glio>Pen>A. ver=Tri 7.4x104 G neg>>Bac>ActV3 (crawlspace soil under AHU 13) 3.7x103 Pen>stf>Tri 1.9x104 Sta>Pen=Y>stf>Pho=Pith 1.8x105 G neg=BacV4 (crawlspace soil 2 under AHU 12) 3.7x104 Clad>Acr>Ver=Trit>stf 2.4x104 Clad>Acr>Trit>Glio=Pho=

Pith=Ver4.4x106 G neg>>Mic>

Rho>BacV5 (crawlspace soil at water incursion point 1) 344 Tri 344 Tri 4.7x104 BacV6 (crawlspace soil at water incursion point 2) 1.1x103 Pen=Tri=Muc 2.2x103 Y>Tri=Muc 3.7x104 BacV7 (Home and Family – debris from diffuser) 5.5x104 Pen>>Chae>stf 4.1x104 Pen>>stf>Clad=Epi=Y 2.3x105 BacV8 (Business – debris from diffuser) 9.2x104 Y>Pen>Clad>Curv 1.4x105 Y>Aur=Clad=Pen>

Alt=Rho 1.8x105 G neg>Bac

V9 (AHU 12 – water in exterior insulation) 440 Pho>Myc=Acr 220 Pen=Tri 1.1x104 Bac

Acr – Acremonium Epi – Epicoccum nigrum Spo – Sporobolomyces Bac – BacillusA ver – Aspergillus versicolor Mon – Monodictys Sta – Stachybotrys chartarum G neg – Gram negativeAlt – Alternaria Muc – Mucor stf – sterile fungi Mic – MicrococcusAur – Aureobasidium pullulans Myc – Mycotypha Tri – Trichoderma Rho – RhodococcusChae – Chaetomium Pen – Penicillium Trit – TritirachiumCur – Curvularia Pho – Phoma Ver – VerticilliumClad – Cladosporium Pith – Pithomyces Y – unidentified yeastGlio – Gliomastix Rho – Rhodotorula


SampleLocation Date

Concentration(spores/m3)

TaxonomicRank

Computer Lab 9/15/97 20 Clad>Asp/Pen

9/16/97 10 Asp/Pen=hyph

Room 100 9/15/97 30 Clad>unk>Alt

Spanish 9/16/97 10 unk

Business 9/15/97 40 Asp/Pen>Clad=Epi>Alt

9/16/97 10 Clad=unk

Home and Family 9/15/97 10 Clad=unk

9/16/97 20 unk>hyph

CAD 9/15/97 10 Clad>unk

Faculty lounge 9/16/97 30 Clad>unk

Outdoors 9/15/97 220 Clad>>asc>unk>bas>hyph>Sco>Asp/Pen

9/16/97 170 Clad>>unk>Asp/Pen>asc>bas

Crawlspace 9/16/97 40 unk>Stachy

asc = ascosporesAlt = AlternariaAsp/Pen = Aspergillus/Penicillium likebas = basidiosporesClad = Cladosporium

Epi = Epicoccumhyph = hyphal fragmentsSco = ScopulariopsisStachy = Stachybotrysunk = unknown

Table 3. Spore Air Sampling Results


0

200

400

600

800

1000

1200

1400

1600

1800

2000 M

icro

bial

Con

cent

ratio

n (C

FU/m

3)

0%

20%

40%

60%

80%

100%

A B C D E F G H ISample Location

A - Computer Lab B - Room 100 C - Spanish (Room 102) D - Business (Room 300) E - Home & Family (Room 302) F - CAD (Room 303) G - Faculty Lounge H - Outdoor I - Crawl space

PercentPenicillium sp.

Estimated concentrationand Aspergillus/Penicilliumpercentages due to overgrowth

Aspergillus sp.present

Figure 1. Culturable Air Sample Results for Fungi

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