NIOSH HEALTH HAZARD EVALUATION REPORT 

HETA #2005-0112-2980 

Taft Elementary School 

Santa Ana, California 

September 2005 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health
ii 

PREFACE

The Hazard Evaluation and Technical Assistance Branch (HETAB) of the National Institute for 

Occupational Safety and Health (NIOSH) conducts field investigations of possible health hazards in the 

workplace. These investigations are conducted under the authority of Section 20(a)(6) of the 

Occupational Safety and Health (OSHA) Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary 

of Health and Human Services, following a written request from any employers or authorized 

representative of employees, to determine whether any substance normally found in the place of 

employment has potentially toxic effects in such concentrations as used or found. 

HETAB also provides, upon request, technical and consultative assistance to federal, state, and local 

agencies; labor; industry; and other groups or individuals to control occupational health hazards and to 

prevent related trauma and disease. Mention of company names or products does not constitute 

endorsement by NIOSH. 

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by David Vinson, Eric Esswein, and Elena Page of HETAB, Division of 

Surveillance, Hazard Evaluations and Field Studies (DSHEFS). Analytical support was provided by 

Joseph Fernback and Eileen Birch. Desktop publishing was performed by Elaine Moore. Editorial 

assistance was provided by Ellen Galloway. 

Copies of this report have been sent to employee and management representatives at Taft Elementary 

School, the Santa Ana Unified School District, and the OSHA Regional Office. This report is not 

copyrighted and may be freely reproduced. The report may be viewed and printed from the following 

internet address: http://www.cdc.gov/niosh/hhe. Copies may be purchased from the National Technical 

Information Service (NTIS) at 5825 Port Royal Road, Springfield, Virginia 22161. 

For the purpose of informing affected employees, copies of this report 

shall be posted by the employer in a prominent place accessible to the 

employees for a period of 30 calendar days.
iii 

Highlights Page should be inserted hereHighlights of Health Hazard Evaluation 

Highlights of the NIOSH Health Hazard Evaluation

Evaluation of Respiratory, Allergic, and Neuropsychological Complaints from 

Possible Mold Exposure

NIOSH received a confidential employee request for a health hazard evaluation at Taft Elementary 

School in Santa Ana, California, on February 1, 2005. The requesters were concerned about exposure to 

“toxic mold” in the school, with reports that teachers had been diagnosed with toxic encephalopathy 

(brain damage); other complaints included migraine headaches, sinusitis, asthma and other health 

conditions. 

What NIOSH Did

 We took indoor environmental quality 

measurements, including temperature, 

humidity, and carbon dioxide, as well as 

moisture meter readings of walls and 

ceilings. 

 We inspected the ventilation systems. 

 We took samples of air filters and analyzed 

them. 

 We reviewed medical records and 

interviewed employees about work-related 

exposures and symptoms. 

What NIOSH Found

 We did not identify any health hazard. 

 There was no evidence of significant mold 

contamination or of toxic encephalopathy. 

 We could not conclusively link any reported 

symptoms directly to the school. 

 We found no moisture in the walls, ceiling 

tiles, or wood framing. 

 Minor deficiencies were identified in the 

ventilation systems. 

 Air filters contained mineral fragments, skin 

cells, pollen, mold spores, and rubber dust 

and diesel particulates from air pollution. 

What Santa Ana Elementary School 

Managers Can Do

 Address the minor ventilation deficiencies. 

 Implement an IEQ Management Plan for the 

Santa Ana Unified School District. 

 Ensure that classrooms are cleaned and 

dusted at regular intervals. 

What the Santa Ana Elementary School 

Employees Can Do 

 Communicate your concerns to the correct 

school district officials. 

 Do not divert air flow at supply or exhaust 

vents. 

 Seek medical care from a residency trained, 

board-certified occupational medicine 

physician for work-related symptoms. 

What To Do For More Information:

We encourage you to read the full report. If you 

would like a copy, either ask your health and 

safety representative to make you a copy or call 

1-513-841-4252 and ask for 

HETA Report #2005-0112-2980
iv 

Health Hazard Evaluation Report 2005-0112-2980 

Taft Elementary School 

Santa Ana, California 

July 2005 

David Vinson, Jr., MD 

Eric Esswein, MSPH, CIH, CIAQP 

Elena Page, MD, MPH 

SUMMARY

On February 1, 2005, the National Institute for Occupational Safety and Health (NIOSH) received a 

confidential employee request for a health hazard evaluation (HHE) at the Taft Elementary School in the 

Santa Ana Unified School District (SAUSD) in Santa Ana, California. The requesters were concerned 

about exposure to “toxic mold” in the school. There were reports that teachers had been diagnosed with 

toxic encephalopathy (brain damage) while other complaints included migraine headaches, sinusitis, 

asthma and other health conditions related to toxic mold exposure in the school. A site visit was made on 

April 5–6, 2005, which included an opening conference, an inspection of the school, and confidential 

employee interviews. A closing conference was held in which preliminary findings and recommendations 

were presented. 

Measurements of indoor environmental quality were made including temperature, relative humidity, and 

carbon dioxide; and a moisture meter was used to detect moisture in walls and ceilings or wherever 

evidence of water staining was visible in the buildings. Visual inspections were made on each of the five 

30-ton multizone heating, ventilation, and air conditioning (HVAC) units and on 6 of the 12 Trane® 

(3-ton) air handling units (AHUs). To investigate the nature of fine black particulates on filters installed 

downstream of the central AHUs, samples of air filters were collected and evaluated using scanning 

electron microscopy. 

Indoor temperature, relative humidity (RH), and carbon dioxide (CO2) in buildings A and B ranged from 

70°–77°, 25%–38% and 569–1060 ppm, respectively. Indoor temperature, RH and CO2 in bungalows 

B-3, B-4, and B-9 ranged from 72°–79°, 41%–58% and 1374–1477 ppm, respectively. Outside 

measurements were 76°–77°, 23% and 443–450 ppm. The presence of moisture was not detected on or in 

walls, ceiling tiles or wood framing members where evidence of previous water staining was visible. 

Microscopy results from air filters revealed various mineral fragments, skin cells, pollen and mold spores, 

and diesel particulates. Other reported particulates appeared physically similar to rubber dust. Minor 

deficiencies were found in several AHUs. 

Fifteen of the 37 (41%) staff members interviewed reported no symptoms related to work. The most 

common work-related symptoms were nasal symptoms such as runny or stuffy nose (8/37 or 22%). 

Work-related eye irritation was reported by four persons (11%). Headache, throat irritation, and cough 

were each reported by three (8%). Two persons described sinus pressure that got better when away from 

work. Nobody reported shortness of breath, chest tightness, or wheezing. Eight of 37 (22%) reported 

constant sinus problems or recurrent sinusitis. Three persons reported memory problems and being 
v 

diagnosed by the same physician with toxic encephalopathy from mold exposure in the school. Medical 

records were also reviewed for seven persons. One person had evidence of sinusitis and rhinitis and one 

had rhinitis. None had evidence of toxic encephalopathy. 

NIOSH investigators did not identify an occupational health hazard at the Taft 

Elementary School. Inspection of the HVAC system revealed minor problems such as 

evidence of dust intrusion, and presence of standing water and biofilm in some of the 

condensate drain pans. All water leaks had been repaired, and there was no evidence of 

mold or fungal growth. Taft employees had rates of work-related nasal problems similar 

to those reported in studies of buildings with indoor environmental quality complaints; 

however, we were unable to directly relate any symptom to the work environment. No 

exposure was identified in the school that would cause toxic encephalopathy, and there 

was sufficient evidence to conclude that none of the Taft Elementary School employees 

interviewed had toxic encephalopathy. Recommendations are included in this report to 

address HVAC deficiencies in all units that were inspected. 

Keywords: School, mold, biofilm, allergy, rhinitis, toxic encephalopathy, memory, indoor environmental 

quality 

NAICS 61111
Table of Contents

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

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

Highlights Page should be inserted hereHighlights of Health Hazard Evaluation ..............................iii

Summary.....................................................................................................................................................iv

Introduction.................................................................................................................................................1

Background .................................................................................................................................................1

Facility Description.................................................................................................................................1

Ventilation Description...........................................................................................................................1

Methods........................................................................................................................................................3

Industrial Hygiene Evaluation...............................................................................................................3

Medical Evaluation .................................................................................................................................4

Evaluation Criteria .....................................................................................................................................4

Symptoms/Illnesses .............................................................................................................................5

Environmental Evaluations................................................................................................................6

Heating, Ventilating, and Air-Conditioning .....................................................................................6

Results ..........................................................................................................................................................8

Industrial Hygiene Evaluation...............................................................................................................8

Observations and Findings From HVAC System Inspections........................................................8

Bulk Sample Results .........................................................................................................................11

Settling Plate Results Review...........................................................................................................11

Medical Evaluation ...............................................................................................................................11

Discussion ..................................................................................................................................................13

Baseline Levels of Symptom Reporting ..............................................................................................13

Memory Problems.................................................................................................................................14

Toxic Encephalopathy ..........................................................................................................................14

Functional Neuroradiologic Imaging ..................................................................................................15

Laboratory Testing of Employees .......................................................................................................15

Use of Settling Plates to Document Fungal Exposure........................................................................16

Conclusions................................................................................................................................................17

Recommendations.....................................................................................................................................18

References..................................................................................................................................................20
Page 1 Health Hazard Evaluation Report No. 2005-0112-2980 

INTRODUCTION

On February 1, 2005, the National Institute for 

Occupational Safety and Health (NIOSH) 

received a confidential employee request for a 

health hazard evaluation (HHE) at the Taft 

Elementary School in the Santa Ana Unified 

School District (SAUSD) in Santa Ana, 

California. The request stated that teachers, 

custodians, aides, secretaries, students, and 

administrative staff had concerns about exposure 

to “toxic mold” in the school. Requesters 

reported that teachers had officially been 

diagnosed with toxic encephalopathy (brain 

damage), migraine headaches, sinusitis, asthma, 

and other health conditions related to toxic mold 

exposure in the school. It was reported that the 

commercially available microbiological settling 

plates placed in several locations in the school 

by teachers had demonstrated fungal growth. 

After review of the HHE request and telephone 

consultations with the requesters and risk 

management officials for the school district, a 

site visit was made on April 5–6, 2005. An 

opening conference was held with the school 

district risk manager, three representatives of the 

Santa Ana Educators Association (one each for 

the elementary school, intermediate school, and 

deaf and hard of hearing school), a 

representative of the California State Employees 

Association (which represents the non-teaching 

staff), and the principal. Following the opening 

conference, a walk-through survey of the 

facilities and confidential employee interviews 

were conducted. At the end of the visit, a closing 

conference was held in the school; teachers and 

staff were invited to this meeting, along with 

those from the opening conference. 

BACKGROUND

Facility Description 

The Taft elementary school consists of two main 

buildings (designated as A and B) that are 

rectangular in shape. The main building 

(building A) was constructed in 1971 and 

building B was added a year later. Building A 

houses kindergarten through grade 5, and 

building B houses the deaf and hard of hearing 

school. The school also includes 20 prefabricated modular buildings (referred to as 

bungalows) that are used as classrooms and are 

designated B1-B20. Some of these bungalows 

house the intermediate school (grades 6-8), and 

others house elementary students. A modular 

restroom building is also on the school grounds 

adjacent to B-9. Taft Elementary School is 

situated near several major highways and the 

Orange County Airport. Also, it is located 

approximately 2 miles from an agricultural field. 

Buildings A and B are single story, slab-ongrade structures with poured concrete walls and 

a flat roof finished with rolled asphalt roofing 

material. The two buildings are connected only 

by roofing that extends over an atrium or 

courtyard area. Teaching areas in buildings A 

and B are configured in the open classroom 

concept with partitions in some locations and 

bookcases and other storage systems forming 

walls as needed or desired. The pre-fabricated 

bungalows appear to be of standard stud wall 

construction finished on the outside with painted 

wood siding and a gutterless, pitched metal roof. 

The school serves 1,310 students and has a 

teaching and administrative staff of 

approximately 125 with an average-yearsteaching of 12. The average class size for grades 

K–3 is 19, for grades 4–6 is 32, and for the core 

subjects the average class size is 30. 

Ventilation Description 

Heating, ventilation, and air conditioning 

(HVAC) is supplied to buildings A and B with 

two different sizes and brands of air handling 

units (AHUs). Three custom manufactured, 30-

ton capacity, constant air volume (CAV), multizone systems serve the east and west (interior 

and perimeter) and the south perimeter (library 

and computer lab) sections of Building A. These 

systems were made for SAUSD by Seasons Four 

(Atlanta, GA). Central classroom areas of the 

building (as well as a section of the perimeter on 

the south side) of building A are supplied by 

twelve 3-ton capacity rooftop package units 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 2 

manufactured by Trane®. The HVAC systems 

for Building B include two 30-ton rooftop 

package units, also manufactured specifically for 

SAUSD by Seasons Four. 

The 30-ton capacity multi-zone units are 

reportedly configured in a dual-duct design that 

can supply natural gas heating or refrigerant 

cooling to the ventilation zone. The AHUs are 

equipped with an economizer mode that allows 

the outside air dampers to open fully, allowing 

100% outside air to be supplied to the building 

for use in what is called “free cooling” (when 

outside air temperature is cooler than building 

return air). When the units are not operating in 

economizer mode, the outdoor air dampers are 

set at 25% of the maximum outside air supply 

volumes. Filtration of outside and return air 

consists of four stainless steel filter racks each 

capable of holding a contiguous section of five 

two-ply polyester panel filters. Filters were 

reported to have a minimum efficiency reporting 

value (MERV) of 6–7, roughly equivalent to a 

25%–30% dust spot rating. Electronic direct 

digital controls are used in these systems. Much 

of the inside of the units are constructed of 

stainless steel, making for ease of cleaning when 

required. Maintenance doors have substantial 

seals and double locking handles. Condensate 

drain pans are single sloped, stainless steel and 

are plumbed to outlet drains and p-traps 

connected to rooftop drains. 

The 3-ton units that serve the central portion of 

Building A are standard Trane® packaged units 

controlled by thermostats located in classrooms 

that can operate in one of the following four 

modes: heat, cool, auto, and continuous fan. The 

rooftop units were configured with outdoor air 

dampers that can be fixed at one of four 

positions including a minimum setting that 

appeared to be 25% of maximum. Outside and 

return air filtration consists of a single two-ply 

polyester panel filter of MERV 6–7 rating (a 

single panel of the same media is installed in the 

30-ton units). Condensate drain pans are single 

sloped plastic, designed with an indented area at 

the drain pan outlet to prevent standing water. 

The drains are plumbed to a p-trap that was 

connected to the rooftop drains. 

The HVAC systems for the bungalows consists 

of through-the-wall, terminal fan coil units 

installed several feet off the ground on the 

exterior walls. The units that were inspected are 

configured with a two-ply polyester panel filter 

(MERV 6–7) with a small condensate pan 

directly below the coil that drains to the ground 

with a drain tube extension. These units ventilate 

directly through the wall into the classroom; 

there is no supply or return duct work. The units 

operate on a manually adjusted timer that 

teachers can reset as often as necessary or when 

ventilation, heating, and cooling are desired. 

A variety of HVAC work was done at the school 

by Penn Air, a local HVAC contactor and 

supplier of air filtration products and duct 

cleaning services. According to a Penn Air 

representative, the 3-ton units were 

reconditioned and ventilation duct work was 

cleaned as part of a reconditioning program at 

the school several years ago. As part of this 

work, a test and balance was performed on the 

five 30-ton multizone AHUs. As part of the 

AHU reconditioning, fiberglass insulation on the 

supply side interiors of the Trane® rooftop units 

was removed and replaced with Astro-Foil®, a 

reflective, insulating material consisting of two 

layers of aluminum foil laminated to two layers 

of polyethylene air-bubble cushioning. The 

contractor reported that Astro-Foil was used to 

“entomb” any residual fiberglass that may have 

remained inside the cabinets after cleaning and 

reconditioning. Visual inspection of the units 

suggested that in addition to cleaning and 

relining, fan housings had also been repainted. 

Duct cleaning reportedly was done for all metal 

ductwork in the ventilation systems for buildings 

A and B. The contractor stated that ductwork 

was cleaned using “air knife” technology that 

involves insertion of a high pressure air whip 

into ducting while the ducts are under negative 

pressure. Debris dislodged by the flailing action 

of the high pressure air whip and nozzle 

assembly is suctioned through the ducts to a 

filtered collection system. 

According to a document sent to NIOSH 

describing the history of indoor environmental 

quality (IEQ) problems at Taft Elementary, 
Page 3 Health Hazard Evaluation Report No. 2005-0112-2980 

some time between 2000 and 2002 (after duct 

cleaning was completed), unknown black debris 

or “soot-like substance” was noted accumulating 

on desks and other interior surfaces. A rumor 

subsequently circulated that black mold was 

present in the ductwork and that ductwork in the 

school would need to be replaced. Because the 

source of the particulates was unknown, the 

contractor advised the school district to install 

point-of-use filtration (3M FiltreteTM rated at 

MERV 14) to prevent debris from being emitted 

from ventilation supply grilles in the classrooms. 

Risk management officials from SAUSD 

apparently were alerted to the misinformation 

relayed to the teachers and advised the teachers 

that mold was not growing in the ducts and the 

information given to them was inaccurate. After 

the point-of-use filters had been installed in the 

classrooms for some time, the filter media began 

to load and became black. The exact 

composition of, or the reservoir of, the black 

colored particulate (presumed to exist) within 

the HVAC system was never determined 

according to the ventilation contractor or school 

officials. 

METHODS

Industrial Hygiene Evaluation 

Taft Elementary staff identified building A as 

the main area of concern in their HHE request; 

however because teachers working in building B 

also mentioned IEQ concerns in the opening 

conference, this building as well as several of 

the bungalows were included in the 

investigation. A walk-through inspection of 

buildings A and B was conducted. 

Measurements of IEQ were made during the 

walk-through inspection including temperature, 

relative humidity, and carbon dioxide (CO2) in 

mid-afternoon when the school was fully 

occupied. A TramexTM non-penetrating moisture 

meter was used to detect the presence of 

moisture in walls and ceilings or wherever water 

stains were visible. Moisture measurements 

were also made in walls at various locations in 

buildings A and B where there was no obvious 

water staining. 

Visual inspections were made on each 30-ton 

multizone AHU and on 6 of the12 Trane® (3-

ton) AHUs. After five of the Trane 3-ton units 

were inspected, it was apparent there were few 

differences in the mechanical condition, 

operating status, filtration, or overall cleanliness 

for the units, so inspection of half of the twelve 

units was judged to be generally representative 

of all these AHUs. 

The evaluation of the HVAC systems was an 

overall assessment, with emphasis on the 

presence of water intrusion, evidence of 

microbiolgical contamination, potential organic 

amplifiers for microbiological growth, and 

potential for dissemination of fungi/molds. We 

also considered overall cleanliness and operating 

condition and inspected the outdoor air intakes, 

dampers, filter racks and condition of filters, 

heating and cooling coils, condensate pans and 

drains, belts, fans, and supply and return 

ducting, terminal diffusers, and filters. For 

viewing of limited access areas, or for inspecting 

lengths of duct run and the internal areas of 

HVAC components, a lighted, flexible fiber 

optic borescope was used. The rooftop area 

around the AHU was inspected for evidence of 

pooling water, adequate rooftop drainage and the 

presence of appropriate plumbing (i.e., water 

filled p-traps) and the presence of rooftop stacks 

or exhausts located in proximity to outside air 

intakes. From the rooftop, adjacent areas around 

the school were noted including the presence of 

two freeways, an airport, the condition of the 

school grounds, and local flora. 

To investigate the composition and possible 

reasons for the black discoloration of the point 

of use filters, bulk samples were cut from two 

filters that had been previously installed in 

classrooms in buildings A and B. Square 

sections of filter media (approximately 100 

cubic centimeters or 4” x 4”) with differing 

degrees of discoloration were removed. After 

sample collection, sections of filter media were 

placed in clean cellulose envelopes and 

delivered to a NIOSH physical scientist for 

physical inspection and analysis using scanning 

electron microscopy. Following microscopy, 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 4 

samples were provided to a NIOSH analytical 

chemist for analysis by NIOSH Manual of 

Analytical Methods (NMAM) Method 5040 

(Diesel Particulate Matter as Elemental Carbon). 

NIOSH Method 5040 is a thermal-optical 

analysis technique for carbon. The total carbon 

in a sample is quantified as organic and 

elemental carbon (OC and EC), but EC is a more 

specific marker of diesel particulate matter. 

The school was occupied at the time of the 

investigation so traditional IEQ measurements of 

occupant comfort normally measured in NIOSH 

investigations were made using a TSI 

VelociCalc and Q Trak indoor air monitors. 

CO2, temperature, and relative humidity were 

assessed on the first day the survey. 

Additionally, chemical smoke tubes were used 

to visually evaluate ventilation airflow patterns 

and to confirm pressurization of buildings A and 

B as well as negative pressurization of restrooms 

in the buildings. 

We also reviewed results from the commercial 

settling plates placed in the school by 

employees. Additionally we reviewed reports 

and files from a recent California Occupational 

Safety and Health Administration inspection and 

spoke with an industrial hygienist on the phone. 

Medical Evaluation 

Confidential interviews were conducted either in 

person or by telephone. The interviews focused 

on job history, overall health, respiratory and 

allergic history, and any symptoms perceived to 

be building related. Each person was asked to 

compare symptoms at school and away from 

school. The three requesters were interviewed, 

as well as individuals who were identified by the 

requesters as having work-related health 

problems. In addition, we selected a 

representative sample of teachers and ancillary 

staff to interview from a map of the school 

buildings that depicted the location of each 

teacher’s classroom and all office staff and 

supportive personnel. We included individuals 

from the two main buildings and from the 

portable buildings, ensuring that interviewed 

employees were located throughout the 

facilities, in order to capture areas that may have 

been differentially affected by IEQ problems. 

We also interviewed people who came to us and 

asked to be interviewed. 

In addition, we reviewed available medical 

records. Authorization for release of information 

forms were signed and faxed to physician 

offices. In addition to obtaining medical records 

from physicians’ offices, some individuals 

provided us with copies of their records. 

EVALUATION CRITERIA

As a guide to the evaluation of the hazards posed 

by workplace exposures, NIOSH field staff 

employ environmental evaluation criteria for the 

assessment of a number of chemical and 

physical agents. These criteria are intended to 

suggest levels of exposure to which most 

workers may be exposed up to 10 hours per day, 

40 hours per week for a working lifetime 

without experiencing adverse health effects. It 

is, however, important to note that not all 

workers will be protected from adverse health 

effects even though their exposures are 

maintained below these levels. A small 

percentage may experience adverse health 

effects because of individual susceptibility, a 

pre-existing medical condition, and/or a 

hypersensitivity (allergy). In addition, some 

hazardous substances may act in combination 

with other workplace exposures, the general 

environment, or with medications or personal 

habits of the worker to produce health effects 

even if the occupational exposures are controlled 

at the level set by the criterion. These combined 

effects are often not considered in the evaluation 

criteria. Also, some substances are absorbed by 

direct contact with the skin and mucous 

membranes, and thus potentially increases the 

overall exposure. Finally, evaluation criteria 

may change over the years as new information 

on the toxic effects of an agent become 

available. 

The primary sources of environmental 

evaluation criteria for the workplace are: (1) 

NIOSH Recommended Exposure Limits 

(RELs),1

 (2) the American Conference of 
Page 5 Health Hazard Evaluation Report No. 2005-0112-2980 

Governmental Industrial Hygienists’ (ACGIH®) 

Threshold Limit Values (TLVs®),2

 and (3) the 

U.S. Department of Labor, Occupational Safety 

and Health Administration (OSHA) Permissible 

Exposure Limits (PELs).3

 Employers are 

encouraged to follow the OSHA limits, the 

NIOSH RELs, the ACGIH TLVs, or whichever 

are the more protective criteria. 

OSHA requires an employer to furnish 

employees a place of employment that is free 

from recognized hazards that are causing or are 

likely to cause death or serious physical harm 

[Occupational Safety and Health Act of 1970, 

Public Law 91-596, sec. 5(a)(1)]. Thus, 

employers should understand that not all 

hazardous chemicals have specific OSHA 

exposure limits such as PELs and short-term 

exposure limits (STELs). An employer is still 

required by OSHA to protect their employees 

from hazards, even in the absence of a specific 

OSHA PEL. 

A time-weighted average (TWA) exposure 

refers to the average airborne concentration of a 

substance during a normal 8- to 10-hour 

workday. Some substances have recommended 

STEL or ceiling values which are intended to 

supplement the TWA where there are 

recognized toxic effects from higher exposures 

over the short-term. 

Indoor Environmental Quality 

Over 70 million American workers spend their 

workday in indoor environments, and a number 

of published studies have reported symptoms 

among occupants of office buildings, schools, 

healthcare facilities, and other indoor work 

locales.4, 5, 6, 7, 8, 9, 10 Since 1972, NIOSH has 

received approximately 3700 requests for 

assistance related to indoor environmental 

quality (IEQ), has conducted over 1250 Health 

Hazard Evaluations (HHEs) and sent over 1850 

informative letters; far more than half (over 

2800) of the requests were received since 1990. 

In 1993, following a primetime news broadcast 

about IEQ that posted the NIOSH phone 

number, a record 814 IEQ-related requests were 

received. Over 160 of these requests were 

randomly selected for HHE site visit 

investigations. We have found that significant 

IEQ improvements can be achieved by 

following standard recommendations related to 

the following four areas: 

1. Operation and maintenance of ventilation 

system and other building components 

2. Remediation of moisture, mold, and odor 

problems 

3. Addressing employee issues through 

administrative controls 

4. Expanding opportunities for workers to 

participate in decision making 

Symptoms/Illnesses 

The symptoms reported by building occupants 

have been diverse and usually are not suggestive 

of any particular medical diagnosis nor readily 

associated with a causative agent. Reports 

demonstrate closer associations of symptom 

occurrence with occupant perceptions of the 

indoor environment rather than with any 

measurement of indoor contaminants or 

conditions.11, 12 A typical spectrum of reported 

symptoms includes headaches, fatigue, itching 

or burning eyes, irritation of the skin, nasal 

congestion, dry or irritated throats, and other 

respiratory symptoms. These symptoms are also 

often experienced by people outside of the 

workplace and could be related to a number of 

different causes, such as respiratory infections, 

allergies, discomfort due to temperature and 

humidity, and stress. Some studies have shown 

that psychological, social, and organizational 

factors may modify individuals’ and 

organizations’ responses to concerns in the 

office environment.5, 13, 14, 15 Typically, workers 

suspect a workplace cause because their 

symptoms appear to be worse while at work and 

better when away from work. 

Less often, illnesses and reactions may be found 

to be related to specific exposures in certain 

building environments. Hypersensitivity 

pneumonitis, Legionnaires' disease, Pontiac 

fever, and carbon monoxide poisoning are all 

caused by specific agent(s) which have been 

found in some building environments. The first 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 6 

three of these conditions can be caused by 

microorganisms. 

Environmental Evaluations 

Although NIOSH investigators have often found 

multiple environmental deficiencies in buildings 

with IEQ complaints, the relationship of these 

environmental deficiencies and symptoms 

reported by building occupants is often unclear. 

Environmental deficiencies observed in the 

indoor environment have been associated with 

inadequate ventilation systems, overcrowding, 

microbiological contamination, outside air 

pollutants, odors, dust or particulate exposures, 

or low level chemical exposures from office 

furnishings, office machines, tobacco smoke, 

cleaning products, personal hygiene products, 

and structural components of the building and its 

contents. Problems related to comfort issues, 

reduced job satisfaction, and stress are 

commonly present where IEQ complaints are 

raised. Comfort problems may be due to 

improper temperature and relative humidity 

conditions, poor lighting, unacceptable noise 

levels, unfamiliar odors, or adverse ergonomic 

conditions. Reduced job satisfaction and stress 

occurring among workers in buildings with IEQ 

concerns may be related to personnel 

organizational factors, conflict among personnel, 

or lack of job security. Poor communication 

between employees and supervisors is a 

particularly common finding in workplaces 

NIOSH has evaluated for IEQ 

concerns. 9, 10, 16, 17, 18

A NIOSH study of 104 buildings where IEQ 

problems were reported found one or more 

deficiencies in the operation, design, or 

maintenance of HVAC systems in 93 of the 

buildings.19 The same study found symptoms 

associated with one or more HVAC deficiencies, 

as well as with poor housekeeping, job conflict, 

being female, and being over 40 years of age.20

A literature review in the early 1990s found 

consistent associations between symptoms and 

air-conditioning, carpets, crowding, use of video 

display terminals, introduction of outside air at 

rates below 10 liters per second per person (ls1/person), job stress/dissatisfaction, being 

female, and having allergies or asthma.5

Standards specific to the non-industrial indoor 

environment do not exist. Measurement of 

indoor environmental contaminants has seldom 

proved helpful in determining the cause of 

symptoms except where there are unusual 

sources, or a proven relationship between 

specific exposures and disease. With few 

exceptions, concentrations of frequently 

measured chemical substances in the indoor 

work environment fall well below the published 

occupational standards or recommended 

exposure limits set by NIOSH, OSHA, and 

ACGIH.1, 2, 21 The American National Standards 

Institute (ANSI)/American Society of Heating, 

Refrigerating, and Air-Conditioning Engineers 

(ASHRAE) has published recommended 

building ventilation and thermal comfort 

guidelines.22, 23 The ACGIH has also developed 

a manual of guidelines for approaching 

investigations of building-related symptoms that 

might be caused by airborne living organisms or 

their effluents.24 Other resources that provide 

guidance for establishing acceptable IEQ are 

available through the Environmental Protection 

Agency (EPA) at (www.epa.gov/iaq,) especially 

the joint EPA/NIOSH document, Building Air 

Quality, A Guide for Building Owners and 

Facility Managers (www.epa.gov/iaq/largebldgs/ 

baqtoc.html) and the EPA Indoor Air Quality 

Building Education and Assessment Model (IBEAM) software available for downloading 

(www.epa.gov/iaq/largeblds/ibeam page.htm). 

Heating, Ventilating, and Air-Conditioning 

One of the most common deficiencies in the 

indoor environment is the improper operation 

and maintenance of ventilation systems and 

other building components.4

 NIOSH 

investigators have found correcting HVAC 

problems often reduces reported symptoms. The 

majority of studies of ventilation rates and 

building occupant symptoms have shown that 

rates below 10 ls-1/person (which equates to 20 

cubic feet per minute per person [cfm/person]), 

are associated with one or more health 
Page 7 Health Hazard Evaluation Report No. 2005-0112-2980 

symptoms.25 Moreover, higher ventilation rates, 

from 10 ls-1/person up to 20 ls-1/person, have 

been associated with further significant 

decreases in the prevalence of symptoms.25

Thus, improved HVAC operation and 

maintenance, higher ventilation rates, and 

comfortable temperature and RH can all 

potentially serve to improve symptoms without 

ever identifying any specific cause-effect 

relationships. When conducting an IEQ survey, 

NIOSH investigators often measure ventilation 

and comfort indicators, such as carbon dioxide 

(CO2), temperature, and RH to provide 

information relative to the functioning and 

control of HVAC systems. 

 

Carbon Dioxide 

 

CO2 is a normal constituent of exhaled breath 

and is not considered a building air pollutant. It 

is an indicator of whether sufficient quantities of 

outdoor air are being introduced into an 

occupied space. However, CO2 is not an 

effective indicator of ventilation adequacy if the 

ventilated area is not occupied at its usual level 

at the time the CO2 is measured. ASHRAE 

recommends that the indoor CO2 concentration 

be no greater than 700 ppm above the outdoor 

concentration for comfort (odor) reasons.23

Elevated CO2 concentrations suggest that other 

indoor contaminants may also be increased. If 

CO2 concentrations are elevated, the amount of 

outdoor air introduced into the ventilated space 

needs to be increased. ASHRAE's most recently 

published ventilation standard, ANSI/ASHRAE 

62.1-2004: Ventilation for Acceptable Indoor 

Air Quality, recommends outdoor air supply 

rates of 17 cfm/person for office spaces and 

libraries, 13 to 15 cfm/person for classrooms 

(depending on the students’ age), 7 cfm/person 

for reception areas, and 5 cfm/person for 

auditoriums.23

 

Temperature and Relative Humidity

 

Temperature and RH measurements are often 

collected as part of an IEQ investigation because 

these parameters affect the perception of 

comfort in an indoor environment. The 

perception of thermal comfort is related to one's 

metabolic heat production, the transfer of heat to 

the environment, physiological adjustments, and 

body temperature.26 Heat transfer from the body 

to the environment is influenced by factors such 

as temperature, humidity, air movement, 

personal activities, and clothing. The 

ANSI/ASHRAE Standard 55-2004: Thermal 

Environmental Conditions for Human 

Occupancy, specifies conditions in which 80% 

or more of the occupants would be expected to 

find the environment thermally acceptable.22

Assuming slow air movement and 50% RH, the 

operative temperatures recommended by 

ASHRAE range from 68.5o

F to 76oF in the 

winter, and from 75o

F to 80.5oF in the summer. 

The difference between the two is largely due to 

seasonal clothing selection. ASHRAE also 

recommends that RH be maintained at or below 

65%.23 Excessive humidity can promote the 

excessive growth of microorganisms and dust 

mites. 

Microbial Contamination

Concern about IEQ problems related to 

microbial contamination, especially molds, in 

the workplace has been increasing with 

heightened public awareness, primarily through 

the popular media. However, exposure to 

microbes in the indoor environment is not a new 

exposure problem, and exposure to microbes is 

not unique to the indoor environment. It is 

important to understand that no environment, 

indoors or out, is completely free from microbes, 

not even a surgical operating room. 

Nevertheless, numerous public media reports 

and several scientific studies have suggested an 

association between building occupant 

symptoms and indoor fungi (mold), bacteria, or 

endotoxin concentrations, although most of 

these have recently focused on mold exposure. 

Similar to improving HVAC operation and 

maintenance, remediation of microbial 

contamination may improve IEQ conditions 

even though a specific cause-effect relationship 

is not determined. NIOSH investigators 

routinely recommend the remediation of 

observed microbial contamination and the 

correction of situations that are favorable for 

microbial growth and bioaerosol dissemination. 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 8 

Mold

 

The types and severity of symptoms related to 

exposure to mold in the indoor environment 

depend in part on the extent of the mold present, 

the extent of the individual’s exposure, and the 

susceptibility of the individual (for example, 

whether they have pre-existing allergies or 

asthma). In general, excessive exposure to fungi 

may produce health problems by several primary 

mechanisms, including: (1) allergy or 

hypersensitivity, (2) infection, and (3) toxic 

effects. Additionally, molds produce a variety of 

volatile organic compounds, the most common 

of which is ethanol, that have been postulated to 

cause upper airway irritation.27 However, the 

potential irritant effects of VOCs from exposure 

to mold in the indoor environment are not well 

understood. 

 

Allergic responses are the most common type of 

health problem associated with exposure to 

molds. These health problems may include 

sneezing; itching of the nose, eyes, mouth, or 

throat; nasal stuffiness and runny nose; and red, 

itchy eyes. Repeated or single exposure to mold 

or mold spores may cause previously nonsensitized individuals to become sensitized. 

Molds can trigger asthma symptoms (shortness 

of breath, wheezing, cough) in persons who are 

allergic to mold. A recent review of the 

scientific literature concluded that exposure to 

molds in the indoor environment may make preexisting asthma worse, but also concluded that 

there was not enough evidence to determine 

whether exposure to mold in the indoor 

environment could cause asthma.28

Hypersensitivity pneumonitis (HP) is another 

allergic response that has developed in people 

following extensive short-term (acute) or longterm (chronic) exposure to molds. It is a very 

rare illness, which may resemble bacterial 

pneumonia, and typically involves respiratory 

symptoms (such as cough, wheezing, or 

shortness of breath) as well as other symptoms 

(such as extreme fatigue and low-grade fever). 

 

People with weakened immune systems 

(immune-compromised or immune suppressed 

individuals) may be more vulnerable to 

infections by molds. For example, Aspergillus 

fumigatus, a mold that has been found almost 

everywhere on every conceivable type of 

substrate, has been known to infect the lungs of 

immune-compromised individuals after 

inhalation of the airborne spores.29 Healthy 

individuals are usually not vulnerable to 

infections from airborne mold exposure. 

Recently, there has been increased concern 

related to exposure to specific molds which 

produce toxic substances called mycotoxins. 

Illness associated with exposures (from 

inhalation and/or skin contact) to mycotoxins in 

agricultural or industrial environments has been 

reported. However, there is currently no 

conclusive evidence of a link between 

mycotoxin exposure in the indoor environment 

and human illness.30, 31, 32 It is important to note 

that many molds can potentially produce toxins 

given the right conditions. 

No exposure guidelines for mold in air exist, so 

it is not possible to distinguish between “safe” 

and “unsafe” levels of exposure. Nevertheless, 

the potential for health problems is an important 

reason to prevent indoor mold growth and to 

remediate any indoor mold contamination. 

Moisture intrusion along with nutrient sources 

such as building materials or furnishings allows 

mold to grow indoors, so it is important to keep 

the building interior and furnishings dry. NIOSH 

concurs with the EPA’s recommendations to 

remedy mold contamination in indoor 

environments (www.epa.gov/iaq/molds/mold_

remediation.html ).33, 34

RESULTS

Industrial Hygiene Evaluation 

Observations and Findings From HVAC 

System Inspections 

An inspection of AHU MZ-4 revealed four rows 

of two-ply Tri-Dim panel filters (Tri-Dek model, 

rated to MERV 6) securely in place with a light 

accumulation of grey dust on the upstream face 

of the filters. Filter bypass was not evident; the 
Page 9 Health Hazard Evaluation Report No. 2005-0112-2980 

coils were clean on both the upstream and 

downstream sides. The interior of the AHU was 

very clean. The outdoor air intake was 

unobstructed and was not located near obvious 

air pollutant sources, standing water, or rooftop 

stacks. The condensate drain pan was dry and 

clean, and slope was confirmed with the use of a 

hand held level. A p-trap was installed and 

functional. The fan blades on the blower were 

free of dirt or other accumulated material. Other 

components such as belts, dampers, seals on 

access doors, and the exterior of the unit, 

controls, etc. appeared to be in good operational 

condition. 

On AHU MZ-5, the outdoor air intake was 

unobstructed and functional. Four rows of 

MERV 6 Tri-Dim filter panels were in place and 

filter bypass was not evident, however, some 

dust was visible on the upstream side of the 

evaporator coil, suggesting that some filter 

bypass had occurred. Light grey dust was visible 

across most of the upstream side of the filter 

faces. Outside air and return air damper linkages 

were intact and operational. There was water 

and a slight build-up of biofilm in the last 7/8 

section of the condensate drain pan, indicating 

that the pan was not draining completely. Other 

components such as belts, dampers, seals on 

access doors, the exterior of the unit, controls, 

etc. appeared to be in good operational 

condition. 

On AHU MZ-1, four rows of MERV 6 Tri Dim 

filter panels were in place and filter bypass was 

not visually evident. Filters had a thin layer of 

grey dust on the upstream side, the coil was 

clean, the outdoor air intake was unobstructed, 

and all dampers appeared to be functional. Clear 

standing water to the depth of an inch or more 

was present in the lower section of the 

condensate drain pan. There was a notable 

accumulation of green vegetative matter near the 

drain outlet. A thin biofilm was present in the 

bottom of the pan. The condensate drain was 

blocked. A thin curled strip of what appeared to 

be metal shavings (likely from installation of the 

unit) and a blob of cured sheet metal sealant was 

removed from the drain inlet. When the plug 

was removed, the standing water drained freely 

from the pan. Other components such as belts, 

dampers, seals on access doors, the exterior of 

the unit, controls, etc. appeared to be in good 

operational condition. 

On AHU MZ-2, four rows of Tri-Dim MERV 6 

filter panels were in place and filter bypass was 

not visually evident. Filters had a notable 

accumulation of tan-colored dust visible on the 

upstream side. The coil was clean, the outdoor 

air intake was unobstructed, and all dampers 

appeared to be functional. The bottom of the 

condensate drain pan was covered with a thin 

tan and green biofilm, and a small amount of 

standing water was present in the lower section 

of the drain pan. The reason for the standing 

water was undetermined. The insulating sound 

baffle on the building return air side had notable 

accumulations of tan dust that appeared to be the 

same color as the soil from the playground. 

Other components such as belts, dampers, seals 

on access doors, the exterior of the unit, 

controls, etc. appeared to be in good operational 

condition. 

On AHU MZ-3, four rows of Tri-Dim MERV 6 

filter panels were in place and filter bypass was 

not visually evident. Filters had light 

accumulations of grey dust on the upstream side. 

The coil was clean, the outdoor air intake was 

unobstructed, and all dampers appeared to be 

functional. The bottom of the condensate drain 

pan was dry but some debris was present. Other 

components such as belts, dampers, seals on 

access doors, the exterior of the unit, controls, 

etc. appeared to be in good operational 

condition. The maintenance access door to the 

coil section could not be opened completely 

because a horizontal section of the natural gas 

line for the unit was installed incorrectly. 

Six of the Trane® 3-ton AHUs were inspected. 

These units were not numbered on the exterior 

of the cabinets and were identified by serial 

numbers listed on the manufacturer’s label. 

On Unit 325101504L, a single panel filter was in 

place and had a thin layer of grey dust on the 

upstream side, the coil was clean, and the drain 

pan was dry but a thin layer of tan dust/soil was 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 10 

present in the bottom. No rust was evident inside 

the unit, and the Astro-Foil lining was intact and 

well sealed at the back and along the edges. Dust 

intrusion into the unit was evident due to lack of 

an adequate flat rubber seal along the edge of the 

maintenance access panel. The unit was missing 

a plastic plug designed to fill a half round 

conduit void built into the sheet metal frame that 

separates the filter side of the unit from the coil 

side. The absence of this plug allows some 

degree of filter bypass. 

On Unit N1728S331H, a single MERV 6 filter 

was in place and had a moderate amount of grey 

dust on the upstream side; the coil was clean. 

The drain pan was slightly damp and contained a 

thin layer of dust or soil. No rust was evident 

inside the unit. The Astro-Foil lining was intact 

and sealed at the back and along the edges. Dust 

intrusion into the unit was evident on the fan 

blades. This was apparently due to lack of an 

adequate rubber seal along the edge of the 

maintenance access panel as well as possible 

filter bypass, again because the unit was missing 

the plastic plug to fill the conduit void in the 

sheet metal frame. 

On unit R0334F81H, a single MERV 6 filter 

was in place and had a moderate amount of grey 

dust on the upstream side; the coil was clean. 

The drain pan was slightly damp and contained a 

thin layer of dust or soil. No rust was evident 

inside the unit, and the Astro-Foil lining was 

intact and sealed at the back and along the 

edges. Dust intrusion was evident by a build up 

on the fan blades. This was apparently due to 

lack of an adequate rubber seal along the edge of 

the maintenance access panel as well as possible 

filter bypass because the unit was missing a 

plastic plug to fill a round conduit void in the 

sheet metal frame separating the filter side from 

the coil side. 

On Unit P244TRO1H, a single MERV 6 filter 

was in place and had a moderate amount of grey 

dust on the upstream side; the coil was clean. 

The drain pan was dry but contained a thin layer 

of dust and dirt. Rust was not evident inside the 

unit. The Astro-Foil lining was intact and sealed 

at the back and along the edges. Dust intrusion 

was evident by dust streaking along the edges of 

the maintenance access panel. Some degree of 

filter bypass was possible because the unit was 

missing a plastic plug to fill a round conduit 

void in the sheet metal frame separating the 

filter side from the coil side of the unit. 

On Unit N19275C1H, a single MERV 6 filter 

was in place and had a moderate amount of grey 

dust on the upstream side; the coil was clean. 

The drain pan was dry and contained a very thin 

layer of tan colored dust and dirt. Rust was not 

evident inside the unit. The Astro-Foil lining 

was intact and sealed at the back and along the 

edges. Dust intrusion was evident by dust 

streaking along the edges of the maintenance 

access panel. Some of the maintenance panel 

screws were missing. Filter bypass was possible 

because the unit was missing a plastic plug to fill 

a round conduit void in the sheet metal frame 

separating the filter side from the coil side. 

On Unit R043XCN1H, a single MERV 6 filter 

was in place and had a moderate amount of grey 

dust on the upstream side; the coil was clean. 

The drain pan was dry and contained a thin 

coating of dust. Rust was not evident inside the 

unit. The Astro-Foil lining was intact and sealed 

at the back and along the edges. Dust intrusion 

was apparent by the presence of dust streaks 

along the edges of the maintenance access panel 

where a flat rubber gasket was missing. The 

plastic plug was installed in the conduit cut out 

of the sheet metal frame that separates the filter 

side from the coil side of the unit. 

Ceiling plenums (the areas above the suspended 

ceiling tiles) were inspected in areas with water 

stained ceiling tiles in buildings A and B. 

Generally, an inspection revealed that a pipe 

elbow for a roof drain was located above the 

water stained area. Apparently there had been 

roof leaks around the drains, and the presence of 

the black mastic roofing cement around the 

perimeter of pipe/roof seal suggested that the 

area had been repaired. Ducting was also 

inspected at this time, and it was noted that 

return air for building A used a ceiling plenum 

return. In building B, return air was not via the 

ceiling plenum; rather, round ductwork had been 
Page 11 Health Hazard Evaluation Report No. 2005-0112-2980 

installed. Water staining was evident in some 

area of the ceiling plenum but it did not appear 

to be recent. Mold or fungi, or the presence of 

water damage from chronic water intrusion was 

not seen in any location. While fine grey dust 

was present in some sections of flex ducting 

leading to point of use filters, mold or fungal 

growth was not observed in any of the ductwork 

that was inspected, nor was the characteristic 

smell of mold detected by the investigators. In 

one location (classroom 23 of building A) a 

section of batt insulation had come loose. The 

area was localized and was not determined to be 

an issue from an IEQ perspective. 

Temperature, RH, and CO2 measured in building 

A ranged from 71°–77°, 25%–35% and 569–

1060 ppm, respectively. Outside measurements 

at 2:22 pm were 77°, 23%, and 443 ppm. It was 

noted that several outside doors were open in 

building A when these measurements were 

taken. 

Temperature, RH, and CO2 measured in building 

B ranged from 70°–77°, 30%–38% and 615–685 

ppm, respectively. Outside measurements at 

1:30 pm were 76°, 23%, and 450 ppm. Several 

doors were open in building B when these 

measurements were collected. 

 

In Bungalow B-3, interior water staining was 

evident on a section of the north classroom wall 

where the ceiling and wall adjoin. The most 

likely reason for the water intrusion was the 

presence of a wall penetration for electrical 

conduit containing phone and fire alarm 

systems. No moisture was detected on the wall, 

the ceiling, or the wood above the ceiling tiles 

where water staining was visible. Temperature 

was 72°, RH was 45% and CO2 was 1477 ppm. 

The classroom was fully occupied by students 

and the teacher. In Bungalows B-4 and B-9, 

localized water stains were evident in some 

areas and were investigated using a moisture 

meter. Measurements did not indicate the 

presence of moisture behind walls, in wallboard, 

or ceiling tiles or in wood framing or header 

components. Temperature, RH, and CO2 was 

measured at 79°, 41%, and 1374 ppm in B-4 and 

74°, 58%, and 1445 ppm in B-9. 

Bulk Sample Results 

Results of scanning electron microscopy of the 

two samples of point of use filters revealed the 

physical composition was similar for both 

samples. The filter from building A was more 

heavily loaded than the filter from building B, 

and this was consistent with visual observations 

when the samples when collected. The following 

materials and substances were reported by the 

NIOSH analyst: various mineral fragments, skin 

cells, pollen, and mold spores. Numerous small 

particles that could not be readily identified were 

also reported. The analyst commented that the 

materials seen under scanning electron 

microscopy were similar to other air samples of 

air filters that he had analyzed. The presence of 

“spongy appearing particles” was reported with 

the comment that they appeared physically 

similar to reference photographs of rubber dust. 

Numerous round particles were seen that were 

reported to be diesel particulates. 

Based on this initial analysis, the filters were 

analyzed by NIOSH Manual of Analytical 

Methods (NMAM) Method 5040 for the 

presence of diesel particulate matter. Thermal 

optical analysis was conducted with a flame 

ionization detector and confirmatory results 

indicated the presence of total carbon, which is 

indicative of diesel exhaust particulates. The 

presence of diesel exhaust particulate was 

reported on both filter samples. 

Settling Plate Results Review 

Microbiological results for the environmental 

settling plates reported minor amounts of fungal 

growth, from one to ten colonies of common 

environmental fungi, including Cladosporium, 

Ulocladium, and Penicillium. 

Medical Evaluation 

Thirty-seven employees were interviewed, three 

by telephone and the rest in person. Of the 37, 

there were nineteen teachers, three custodians, 

eight teacher’s aides, four administrators, and 

one school nurse. The rest were other 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 12 

professional staff, such as audiologists. Thirteen 

of the 37 (35%) were those reported to have 

symptoms that they related to being in the 

school building, two presented themselves for 

interview, and the rest were selected from the 

map as described previously. The average age 

was 42 (range: 23–66), and the average length of 

employment was 12 years (range: 2–36). Five 

employees were men, and one employee 

reported being a current smoker. 

Employees were asked about any medical 

problems or symptoms they had, and whether or 

not they thought the symptoms were work 

related. They were also questioned specifically 

about the relationship of any symptoms to the 

workplace. Symptoms that were reported to be 

better when off work are listed below as workrelated. Prevalence rates of overall symptoms 

are listed in Table 1, and are compared to rates 

in a survey of the general population. 

Fifteen of the 37 (40.5%) staff members 

reported no symptoms related to work. The most 

common work-related symptoms were nasal 

symptoms such as runny or stuffy nose (8/37 or 

21.6%). Work-related eye irritation was reported 

by four persons (10.8%). Work-related 

headache, throat irritation, and cough were each 

reported by three (8.1%). Two persons described 

sinus pressure. Sneezing was reported by one 

person. One person reported having mold spores 

on a nasal swab. One person reported being 

diagnosed with asthma since having worked at 

the building, however, this had been a clinical 

diagnosis with no objective testing such as peak 

flows or spirometry. Two persons had 

preexisting asthma that they reported was not 

worse when in the school. Nobody reported 

shortness of breath, chest tightness, or wheezing. 

Atopy is the genetic predisposition to develop 

the classical allergic diseases, which are allergic 

rhinitis, asthma, and atopic dermatitis or eczema. 

Forty-three percent (16/37) of interviewed 

employees reported a history of allergic rhinitis, 

eczema, and/or asthma, and thus would be 

considered atopic. Atopic employees were 2.4 

times more likely than nonatopic employees to 

report work-related respiratory symptoms. 

Prevalence rates of work-related sysmptoms are 

listed in Table 2, and are compared to rates 

found in a study of buildings where no 

complaints had been made and to rates in a study 

of buildings where IEQ concerns were reported. 

Eight of 37 (22%) reported constant sinus 

problems or recurrent sinusitis. One person 

reported absence of menses for several years, 

but had not had a gynecologic evaluation of this 

problem. One person reported a miscarriage that 

she attributed to workplace exposure. One 

person reported no current symptoms, but 

described an incident 3 years prior where there 

was a significant output of an unknown noxious 

substance from the ventilation system. This 

individual was seen by a university occupational 

medicine clinic and diagnosed with irritant 

bronchitis after an extensive and appropriate 

work-up. This individual’s condition has since 

resolved. The school nurse reported that 

although no formal health surveillance system 

was in place, she did not observe any changes in 

student health complaints in the past several 

years. 

Three persons reported memory problems. 

These were described as forgetting thoughts 

while in conversation, walking into a room and 

forgetting why they intended to go there, 

forgetting phone numbers, and other similar 

things. These individuals reported being 

diagnosed with toxic encephalopathy due to 

mold exposure in the school. They had all been 

diagnosed by the same physician, and several 

other employees had also seen this physician. It 

was reported by the employees that this 

diagnosis was based upon: 1) brain singlephoton emission computed tomography 

(SPECT) and/or positron emission tomography 

(PET); 2) settling plates that they had placed in 

the school; and 3) blood tests for mold exposure. 

One person reported having a test of variables of 

attention (TOVA) performed, but no other 

neuropsychological testing. One of these 

individuals has depression, diagnosed at about 

the time the memory symptoms were reported to 

begin. 

Medical records were reviewed for seven 

persons. Records were reviewed from primary 
Page 13 Health Hazard Evaluation Report No. 2005-0112-2980 

care physicians for two persons, and neither 

documented any work-related complaints. 

Records were reviewed from an ear, nose, and 

throat specialist who had evaluated two persons. 

Both individuals had nasal mucosal 

inflammation on physical exam. Both had CT 

scans of the paranasal sinuses; one was normal 

and the other had evidence of sinusitis. One 

reported a long history of allergies to 

“everything.” The other had allergy testing done 

and was only strongly positive for dust mites. 

There was no reaction to mold. Both were 

diagnosed with chronic rhinitis and mold 

exposure by the ENT physician. 

The brain SPECT results provided for one 

individual demonstrated hypoperfusion of the 

frontal and temporal lobes bilaterally. Results of 

serum tests for this individual were also 

provided, and other employees reported having 

the same tests ordered. Extensive panels of 

immunoassays for fungi were reviewed. Serum 

immunoglobulin G (IgG), immunoglobulin M 

(IgM), immunoglobulin E (IgE), and saliva 

immunoglobulin A (IgA) to a variety of fungi 

were listed, including Stachybotrys chartarum, 

Geotrichium candidum, Phoma herbarium, 

Cladosporium herbarum, and Epicoccum 

nigrum, among many others. Similar tests were 

done for mycotoxins, including satratoxin and 

aflatoxin. Of note, the reference range for all 

results was listed as 0–1600, the units as 

enzyme-linked immunosorbent assay (ELISA), 

and 100% of these tests were positive. 

Autoimmune panels were also reviewed, and 

included anti-centromere, anti-microsomal, antimyocardial, anti-parietal cell, anti-smooth 

muscle, anti-thyroglobulin, and C-3 and C-4 

complement, among many others. Finally, 

chemical antibody panels were reviewed, and 

included IgG, IgM, and IgE to formaldehyde, 

isocyanate, trimellitic anhydride, phthalic 

anhydride, and benzene. These two panels were 

negative. 

One physician had done the primary evaluations 

of several of the teachers as noted above, and 

coordinated referrals to other physicians. Six 

teachers provided us with consent to have this 

physician release their records to us for review 

prior to our site visit, but then all teachers 

withdrew their consent after the site visit. 

DISCUSSION

Baseline Levels of Symptom Reporting 

Taft employees had rates of work-related nasal 

problems similar to those reported in a study of 

buildings where IEQ issues had been reported. 

They also reported high background rates of 

underlying allergy which could explain the 

higher reported rates of work-related nasal 

problems. In addition, chronic daily exposure to 

air pollution in the area is probably a 

contributing factor. Analysis of the point of use 

filters demonstrated that pollutants such as 

rubber dust and diesel exhaust (as well as other 

unknown particles) are being captured by the 

ventilation filtration system. Finally, rates 

reported in this sample of employees may be 

higher than they would be if all employees had 

been interviewed because our entire sample was 

not randomly selected. While we attempted to 

select employees who were representative of 

different job series and locations on the campus, 

40% of the employees were interviewed because 

they had complaints, and these complaints were 

primarily nasal and sinus problems. Finally, 

there was heightened awareness of the suspected 

problem in the buildings; co-workers were urged 

to get tested for mold exposure by some of those 

with symptoms, as well as from lawyers who 

urged employees to join a lawsuit. Other 

symptoms, such as headache and cough, were 

present at or below rates that would be expected 

in the general population and in buildings where 

no IEQ issues had been reported. 

To determine if there is an excess of symptoms 

in a particular setting, such as Taft Elementary 

School, we looked at how common these 

symptoms are in the general population. Nonspecific symptoms, such as headache, eye 

irritation, fatigue, backache, and nausea are 

common. Of the general population, 86%– 95% 

has one or more common symptoms during any 

given 2- to 4-week period, and the average adult 

reports a minimum of one symptom every 4 to 6 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 14 

days.35 These symptoms are rarely caused by 

serious illness. The average adult has two to 

three upper respiratory infections per year, while 

children have between six and eight.36

Symptoms have been demonstrated to be more 

common when pollution or health threats are 

perceived,37, 38 and can be affected by fears, 

emotional triggers, and litigation.39 

Lipscomb reported 1-year symptom prevalence 

rates from three populations in California.40 The 

top four health complaints in these populations 

were stuffy nose or congestion, irritated eyes, 

allergies or asthma, and headaches. Sinusitis is 

the most frequently reported chronic disease in 

the United States, topping arthritis, allergies, and 

hypertension.41 Fourteen percent of U.S. adults 

reported physician diagnosed sinusitis in 2003, 

according to the National Health Interview 

Survey.42

Memory Problems 

The rate of memory problems among Taft 

employees was well below the rates in the 

general population, and the examples of 

problems cited by Taft employees did not appear 

to be out of the ordinary. At least one of the 

persons diagnosed with toxic encephalopathy 

had depression, which could account for the 

symptoms reported. TOVA was the only 

neuropsychological test done, and is typically 

used for diagnosis of attention deficit disorder, 

as it tests attention and not memory per se. 

Memory problems are commonly encountered in 

clinical practice and in the general population. In 

a study of adults in the Netherlands, 38.8% 

overall reported memory problems.43 Another 

study of community- dwelling adults from 

Baltimore found that 22% reported memory 

problems.44 Bolla examined 199 healthy men 

and women between the ages of 39 and 89.45

Sixty-nine percent reported having to keep an 

appointment book, 83% required a grocery list, 

59% used reminder notes and made lists of 

things to do, and 20% reported they had others 

remind them to do things so they would not 

forget. The majority of studies find that selfreported memory problems are not related to 

actual performance, but are attributable mainly 

to depression and mood.44, 46, 47, 48, 49, 50, 51 

Toxic Encephalopathy 

Chronic toxic encephalopathy (CTE) represents 

persistent injury to the brain as a result of 

cumulative or multiple repeated exposures to 

certain neurotoxins, over a period of years. 

Rarely, it can result from a single massive 

exposure that results in a severe acute toxic 

encephalopathy, such as severe carbon 

monoxide poisoning. Clinical manifestations 

usually involve varying degrees of cognitive 

impairment. The earliest signs are often subtle, 

and include changes in behavior, mood, or even 

emotions. Symptoms are persistent, vague, mild 

and nonspecific, many of which are seen with 

other psychological illness like the dementias 

and depression.52 

The routine diagnostic procedures for solventinduced CTE performed in different countries 

was assessed by surveying international experts 

about the methods used to diagnose patients with 

CTE.53 There was broad agreement that a routine 

diagnostic procedure for solvent-induced CTE 

should include an interview and neurological, 

physical, and neuropsychological examinations. 

Only one center always used single-photon 

emission computed tomography (SPECT), and 

one center used SPECT and/or positron emission 

tomography (PET) only when indicated. This 

suggests that these tests are not considered a 

standard part of a workup for CTE. 

Recently, a small number of published reports 

implicated molds and mycotoxins in indoor 

environments as a cause of CTE. However, these 

studies have been reviewed by the Institute of 

Medicine, which concluded that there is 

insufficient evidence that the presence of mold 

or other agents in damp, indoor environments 

causes neuropsychiatric disease.28 We also 

reviewed this literature and concluded there is 

insufficient evidence that mold, mycotoxins, or 

damp environments cause neuropsychiatric 

disease. We found no documentation by the 

single physician involved in the diagnosis of 

CTE among Taft employees of exposure to any 
Page 15 Health Hazard Evaluation Report No. 2005-0112-2980 

agent with sufficient evidence of causing CTE. 

Moreover, neuropsychiatric testing was not 

performed to confirm actual performance 

deficiencies, and there was no mention of 

alternate explanations for employee symptoms, 

including the possibility that the symptoms were 

similar to those found in the general population. 

These types of documentation are necessary to 

clearly assess possible CTE. Diagnoses of workrelated CTE should be made by a physician who 

is residency trained and board certified in 

occupational and environmental medicine or 

toxicology, in consultation with a residency 

trained and board certified neurologist and/or 

psychiatrist. 

Functional Neuroradiologic Imaging 

The brain SPECT we reviewed was performed 

in a patient who was taking antidepressant 

medication, and the report specifically stated 

that clinical correlation with use of that 

medication was needed. 

Detection of abnormalities on brain scans 

requires knowledge of normal variations that 

may be seen on these scans.54 Both PET 

and SPECT are highly variable, even in 

normal subjects.55, 56 Age, gender, handedness, 

environment and alertness at the time of the 

study, glucose levels, and even mood can 

influence results.56, 57 The patient’s thoughts and 

experiences at the time of the scan can 

profoundly affect brain function. Even opening 

or closing the eyes produces dramatic changes.54 

A 1996 paper of the Society of Nuclear 

Medicine Brain Imaging Council (SNMBIC) 

entitled “Ethical clinical practice of functional 

brain imaging”58 states that while SPECT and 

PET are useful in the management of patients 

with stroke, epilepsy, brain tumors, and 

dementia, they have limitations. They note that 

sensitivity and specificity are unknown and 

group patterns can be too subtle to detect in 

individuals. This is especially true in the case of 

toxic exposures, chronic fatigue syndrome, and 

other illnesses like autoimmune disorders, where 

patterns are variable. The SNMBIC clearly state 

that the utility of brain PET and SPECT in the 

management of individual patients is far from 

clear. In addition, they state that the use of 

functional neuroimaging in forensic situations 

such as worker’s compensation and toxic torts is 

inappropriate, and are typically rejected by 

courts. In the years since that publication, only a 

handful of studies looking at functional 

neuroimaging in toxic exposures have been 

published. All suffer from serious methodologic 

problems that preclude concluding that these 

tests are diagnostic in cases of purported toxic 

exposures.59, 60 

Laboratory Testing of Employees 

As noted in the results section, it appears that 

immunoassays to fungi and laboratory results of 

sampling using settling plates were accepted by 

the physicians as documentation of exposure to 

fungi. Misuse and misinterpretation of this type 

of testing prompted NIOSH researchers to 

publish a paper specifically addressing this issue 

just last year.61 We concluded that there is not 

sufficient scientific evidence to support the use 

of immunoassays as biomarkers of exposure to 

fungi for a variety of reasons, including the 

ubiquitous nature of fungi, the lack of specificity 

of fungal antigens, lack of standardized 

procedures and reference reagents, and 

difficulties in interpretation.61 Tests performed 

by the particular laboratory used by the treating 

physician are even more problematic. The 

reports include unrealistic reference ranges. It is 

not possible that the reference range would be 

identical in every antibody test, whether it is 

IgG, IgA, or IgM, or serum and saliva, and for 

each type of fungus and mycotoxins. 

Furthermore, ELISA stands for enzyme linked 

immunosorbent assay, and is not a unit of 

measure. 

The use of chemical antibody tests in this group 

of employees was not appropriate. For example, 

formaldehyde is a fairly ubiquitous chemical and 

is known to be present in homes as well as 

schools or offices, as it is a component of 

particleboard, plywood, countertops, paneling, 

glues, fabric coatings, insulation, and 

disinfectants, to name a few. Trimellitic 

anhydride and phthalic anhydride are both used 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 16 

in the production of plasticizers for various 

resins and in dye manufacturing, among other 

things, and would not be expected to be found in 

a school. Benzene is a solvent that is present in 

gasoline and automobile emissions, and thus is a 

ubiquitous exposure. Biological monitoring for 

benzene is commonly done by measuring 

urinary phenol, or benzene in blood or urine.62 

Extensive serum rheumatologic tests were also 

performed in some of these employees. Studies 

have demonstrated that overuse of these tests 

can lead to unnecessary referrals and further lab 

work. Careless, uneducated use of these tests 

leads to diagnostic confusion and increased 

costs.63 Ordering rheumatologic panels is poor 

practice because they often contain tests not 

relative to the patient.63 Selected rheumatologic 

tests are best used in confirming a diagnosis that 

is made clinically (i.e., the patient has signs and 

symptoms consistent with a particular 

diagnosis). This is true of other medical tests as 

well. Ordering of laboratory and other types of 

tests should be done in a judicious and focused 

manner, complementing the history and physical 

examination, and not in a “shotgun” approach. 

The more tests ordered the higher the likelihood 

of a false positive result or a test that is positive, 

but not clinically significant. 

The ethics and procedures at the laboratory that 

performed all this testing has been called into 

question. Scientists at this laboratory published a 

study of salivary secretory IgA in 2003.64 The 

authors also submitted a patent application 

utilizing the same study, but there were several 

discrepancies between the paper and the patent 

application, leading the editors of the journal to 

express their concern.65 The discrepancies 

systematically magnified the difference between 

cases and controls in this publication, making it 

look like their tests performed better than they 

really did. The Centers for Medicare and 

Medicaid Services (CMS) regulates all 

laboratory testing (except research) performed 

on humans in the U.S. through the Clinical 

Laboratory Improvement Amendments (CLIA). 

In total CLIA covers approximately 175,000 

laboratory entities. The objective of the CLIA 

program is to ensure quality laboratory testing 

[http://www.cms.hhs.gov/clia/]. In May 2005, 

the California Department of Health and Human 

Services, CMS, issued a report on the 

Immunosciences Lab, Inc. finding that the 

laboratory was found to be in non-compliance 

with all of the required conditions in the CLIA 

program.66 The 112-page report specified a 

number of deficiencies pertaining specifically to 

the immunoassays performed on the employees 

from Taft, including failure to make available 

pertinent reference intervals; failure to establish 

written policies for patient preparation, 

collection, storage, preservation, transportation, 

and processing of specimens; failure to 

determine calibration procedures; and failure to 

establish the statistical parameters of control 

materials. The report states that there were no 

guidelines indicating the limits of acceptability 

for accuracy, precision, analytical sensitivity or 

specificity to include interfering substances and 

reference ranges for mold and mycotoxins test 

performed. 

Finally, one person reported that fungal spores 

were found in her nose by nasal swab. This is to 

be expected because, as previously explained, 

fungi are ubiquitous. A Mayo Clinic study 

compared patients with chronic rhinosinusitis to 

healthy controls, and found that 100% of 

controls and 96% of cases had positive fungal 

cultures from their noses.67

Use of Settling Plates to Document Fungal 

Exposure 

Commercially purchased settling plates were 

used by employees to test the school for fungal 

contamination. They demonstrated minor 

amounts of growth of common environmental 

fungi. As noted above and in the evaluation 

criteria, microorganisms, including fungi, are 

ubiquitous, that is, they are present in all indoor 

environments with the possible exceptions of 

specially filtered “clean rooms” in health care 

and industry. The use of environmental settling 

plates for collection and enumeration of indoor 

concentrations of fungi (or bacteria) is not an 

accepted method of sample collection to make 

risk-based characterizations of indoor 

environments. Exposing agar-containing (fungal 
Page 17 Health Hazard Evaluation Report No. 2005-0112-2980 

growth media) settling plates will always result 

in the presence of certain organisms if the plates 

are incubated appropriately. However, using 

settling plates is a naïve and not a particularly 

discriminating tool for characterizing building 

environments for the presence of fungal 

contamination for numerous reasons. Settling 

plates are a passive rather than active method. 

Active sampling methods are preferred and 

incorporate calibrated sampling pumps and 

engineered sample collection devices to draw in 

known quantities of air through specifically 

sized openings that allow for specific volumes of 

air to be sampled and specific fungal particle 

sizes to be collected. Settling plates can be easily 

cross-contaminated during handling and are nondiscriminative in relation to specific particle 

sizes, relying simply on settling velocity of 

particles to land on the growth media. 

Interpretation of results is limited to whatever 

organisms happen to thrive best under the 

conditions when the plates were exposed, and 

subsequently handled and incubated. In other 

words, the results are vague and 

unrepresentative at best, especially considering 

the limited numbers of samples that were 

collected. When industrial hygiene sampling for 

fungal agents is needed (not commonly the case 

if a careful building investigation has been 

conducted), an experienced certified industrial 

hygienist should develop a hypothesis and an 

appropriate sampling strategy to test the 

hypothesis, plan and execute appropriate 

sampling (if even necessary), and interpret 

results considering all sampling conditions. 

CONCLUSIONS

No occupational health hazard was found at the 

Taft Elementary School. We found no exposure 

in the school that would cause toxic 

encephalopathy, and there was sufficient 

evidence to conclude that none of the Taft 

Elementary School employees interviewed has 

toxic encephalopathy. In addition, we are unable 

to directly relate any symptom to the work 

environment, although many of the common, 

non-specific symptoms reported, such as sinus 

problems and headaches, are common in offices 

and schools. A chronic air pollution problem in 

the school area likely contributes to the reported 

upper respiratory and eye symptoms. 

There is evidence that isolated and episodic 

water intrusion/filtration has occurred in a few 

very localized areas of the school. There is no 

evidence that water intrusion is or has been a 

chronic problem or that fungal (mold) 

contamination is a health hazard to staff and 

teachers. Moisture was not detected in walls and 

ceilings. The presence of standing water, a 

biofilm, and biomass were found in several of 

the stainless steel condensate pans for several of 

the 30 AHUs. The reason for the standing water 

was clearly identified in one case (a plugged 

drain). No evidence of downstream 

contamination with mold or fungi in AHU 

components or ductwork was seen. 

Results from this investigation suggest a need 

for drain pan cleaning on some of the Seasons 

Four 30-ton air handlers and preventive 

maintenance on the Trane 3-ton units. The 

problems that were noted are not uncommon 

findings based on NIOSH IEQ investigations in 

commercial and school building AHUs. It is 

anticipated that because the problems were 

determined to be cleanliness and maintenance 

issues, they can be easily addressed. 

We consider indoor dustiness, an issue that was 

reported by some teachers to be a health 

concern, to be a consequence of classroom 

clutter, the widespread use of paper products 

(books, classroom papers, etc.), as well as foot 

traffic transport of dust and “dirt” from the 

outdoor playground. The fact that the entire 

school is carpeted may contribute to dustiness 

depending on rigorousness of housekeeping. The 

types of vacuum cleaners used by the cleaning 

staff were judged to be adequate based on the 

types of filtration used in these units. 

Ventilation distribution in the school can be 

improved through a complete test and balance of 

all the AHUs in building A and B. NIOSH 

investigators do not believe that the point of use 

3M filters that have been installed in the school 

are appropriate for numerous reasons including 

increased duct static pressure and air balancing 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 18 

problems that could be created by installation of 

filtration on the ends of ductwork. Enhancing air 

filtration in the AHUs is believed to be a better 

and more cost effective solution. 

The elevated CO2 levels measured in the 

bungalows on the day of the survey were likely a 

result of insufficient amounts of outside air 

(dilution ventilation) due to insufficient use of 

the through-the-wall, terminal fan coil units by 

teachers in those bungalows. These units are on 

timers that the teachers themselves control, so 

feeling of stuffiness, odors, or perceptions of 

“lack of air” can be remedied by more frequent 

cycling of the units. 

RECOMMENDATIONS

The following recommendations are based on 

observations made during the course of the 

HHE. While we are unable to directly relate any 

symptom to the work environment, many of the 

common, non-specific symptoms reported, such 

as sinus problems and headaches, are common 

in offices and schools, and may be improved by 

the recommendations below. Recommendations 

to address the minor HVAC problems are 

included. 

1. Thoroughly clean all HVAC condensate 

pans that were identified to have biofilm, 

standing water, or debris using a standard 

detergent solution in concentrations 

consistent with product use directions. 

Cleaning should be done when the HVAC 

system(s) are not operating. After cleaning, 

drain pans can be sanitized using sodium 

hypochlorite (common bleach) in 

concentrations of 1%–3% aqueous solution 

(note standard household bleach is 5.25% in 

strength, so dilution is required). A clear 

water rinse should follow any cleaning. The 

angle of tilt on the condensate pans should 

be checked with the use of a hand level. If 

sufficient tilt (to allow drainage when 1 liter 

of clear water [less for the 3-ton units] is 

poured in the pan) is not confirmed, the 

slope of the pans should be modified to 

allow adequate condensate drainage if 

possible. 

2. Install enhanced filtration (in a range of 

MERV 10–12) in the 30-ton units and to the 

degree possible in the 3-ton units. The exact 

MERV rating will depend on maximum 

static pressure limits per AHU 

manufacturer’s specifications. The choice of 

enhanced filtration in the AHU should be 

balanced between better efficiency of the 

filter as well as the fit of the filter within the 

existing filter racks. Filters should be sized 

so that each filter fits snugly into the filter 

racks; there should be no gaps where the 

filters meet with the filter access panel 

doors. 

3. Remove the 3M point of use filters, and 

have a qualified ventilation engineer 

perform a complete test and balance of the 

AHUs in buildings A and B. Ensure teachers 

and other staff do not obstruct supply or 

return vents with papers, cardboard, etc. 

Deliberate obstruction of supply ductwork is 

usually a sign that occupants feel 

uncomfortable from drafts or strong flows 

from the ventilation system. This can be due 

to several things including the placement of 

the diffusers too close to a workstation or an 

imbalanced system, which only becomes 

more imbalanced as more diffusers are 

deliberately obstructed. 

4. Seal the half round conduit voids in the 

sheet metal frames of the 3-ton units using 

appropriately sized strips of foil tape. 

Alternatively, strips of sheet metal and duct 

mastic can be used. If this technique is used, 

this repair should be done using low volatile 

organic compounds emitting materials or 

done during the summer when school is not 

in session. Do not use standard “duct tape” 

(any fabric-based tape with rubber adhesive) 

as the adhesive backing on this type of tape 

eventually oxidizes and hardens and the tape 

loses its ability to adhere to surfaces as 

intended. Additionally, this type of tape, 

despite its name, is not intended for use on 

ductwork. 
Page 19 Health Hazard Evaluation Report No. 2005-0112-2980 

5. Relocate the natural gas line serving AHU 

MZ 3 so that the maintenance access door 

can be opened all the way. 

6. Install flat rubber gasketing material on the 

maintenance access panels for the 3-ton 

units to prevent unfiltered dust intrusion. 

7. Increase the frequency of operation of the 

through-the-wall, terminal fan coil units in 

the bungalows to increase dilution 

ventilation (add more outside air) to address 

problems with stuffiness, odors, etc. 

8. Implement an IEQ Management Plan for the 

Santa Ana Unified School District. An IEQ 

manager or administrator with clearly 

defined responsibilities, authority, and 

resources should be selected. This individual 

should have a good understanding of the 

buildings= structure and function, and should 

be able to effectively communicate with 

occupants. This is a proactive approach that 

can help prevent IEQ problems from 

occurring. Although comprehensive 

regulatory standards specific to IEQ have 

not been established, guidelines have been 

developed by organizations such as the 

ASHRAE, NIOSH, and the EPA. The EPA 

has several publications on IEQ, including 

the IAQ Tools for Schools Action Kit which 

is available at http://www.epa.gov/iaq

/schools/toolkit.html. The Tools for Schools

document discusses IEQ in some detail, and 

includes information on common problems, 

investigative techniques, and solutions to 

specific problems. The basic elements of a 

good IEQ plan include: 

▪Proper operation and maintenance of 

HVAC equipment, including the need to 

accommodate occupants who work during 

hours when the HVAC system is routinely 

cycled off to ensure that adequate 

ventilation is provided. 

▪Overseeing the activities of occupants and 

contractors that affect IEQ (e.g., 

housekeeping, pest control, maintenance, 

food preparation). 

▪Maintaining and ensuring effective and 

timely communication with occupants 

regarding IEQ. 

▪Educating building occupants and 

contractors about their responsibilities in 

relation to IEQ. 

▪Identifying and managing projects that 

may affect IEQ (e.g., redecoration, 

renovation, relocation of personnel,) 

proactively. 

▪Designating a school employee 

representative who can speak for the 

teachers and other employees, and assist 

with communication. 

The NIOSH/EPA Document, Building Air 

Quality: A Guide for Building Owners and 

Facility Managers may be helpful for 

developing and implementing the IEQ 

management plan. A companion 

NIOSH/EPA guide: Building Air Quality 

Action Plan can serve as a checklist for 

developing and assessing an effective IEQ 

management program. These are available at 

http://www.cdc.gov/niosh/98-123a.html and 

http://www.cdc.gov/niosh/baqtoc.html, 

respectively. The EPA has also established 

an IEQ information clearinghouse 

 that can provide information on a 

number of IEQ-related topics and has a 

website specifically for IEQ issues 

(http://www.epa.gov/iaq/index.html). 

Information on selecting IEQ consultants, if 

needed, is available from the American 

Industrial Hygiene Association=s (AIHA)

Guidelines for Selecting an Indoor Air 

Quality Consultant. 

9. Encourage employees with health concerns 

to seek evaluation and care from a physician 

who is residency trained and board certified 

in occupational medicine, and is familiar 

with the types of exposures employees may 

have had and their health effects. You can 

locate these occupational medicine 

physicians through a variety of sources, 

including the Association of Occupational 
Health Hazard Evaluation Report No. 2005-0112-2980 Page 20 

and Environmental Clinics at 

www.aoec.org, and the American College of 

Occupational and Environmental Medicine 

(ACOEM) at www.acoem.org. The 

University of California at Irvine has a large 

occupational and environmental medicine 

clinic that could serve all your needs. It may 

be useful to provide the physician with a 

copy of this report. 

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Table 1 

Comparison of Overall Symptom Prevalence Between Taft Elementary 

Employees and the General Population

 General Populationa,b Taft 

Dry, itchy, or irritated 

eyes 

23.2-24.7 16.2 

Runny or Stuffy Nose 28.1-46.2 32.4 

Headache 18.4-33 27.0 

Dry or Sore throat 11-22.4 8.1 

Cough 25.9 8.1 

Allergies or asthma 18.6 43.2 

Fatigue 13.9-29.8 5.4 

Dizziness 11 2.7 

Skin rash, dry skin 12 10.8 

Nausea 5-9 0 

Muscle aches or pain 11.9 10.8 

Table 2 

Comparison of Work-related Symptom Prevalence Between Taft Elementary Employees 

And Workers in Buildings With and Without IEQ Complaints

56 Noncomplaint Buildingsa 80 Complaint Buildingsb Taft 

 Female Male 

Dry, itchy, or irritated eyes 22 14 30.0 10.8 

Runny or Stuffy Nose or Sinus 

Congestion

15 8 21.0 21.6 

Headache 20 8 25 8.1 

Dry or Sore throat 7 4 16.0 8.1 

Cough 6 3 9 

Sneezing 14 6 18.0 2.7 

Fatigue 18 9 25 0 

Dizziness 4 1 0 

Skin rash, dry skin 6 2 9 0 
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