Health Hazard Evaluation Report 2015-0011-3253 Page 1

Evaluation of indoor air quality concerns at 

an outpatient medical clinic in a shared-use 

building – West Virginia 

Report No. 2015-0011-3253

May 2016

Brie Hawley, PhD, MS

Stephen Martin, PhD, PE

Christopher Mugford, MS

Randy Boylstein, MS

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Page 2 Health Hazard Evaluation Report 2015-0011-3253

Contents

Highlights...............................................i

Abbreviations .......................................v

Summary............................................... 1

Introduction......................................... 3

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

Results & Discussion............................ 5

Conclusions........................................ 13

Recommendations............................. 14

References.......................................... 16

Acknowledgements........................... 20

The employer is required to post a copy of this report for 30 days at or near the 

workplace(s) of affected employees. The employer must take steps to ensure 

that the posted report is not altered, defaced, or covered by other material.

The cover photo is a close-up image of sorbent tubes, which are used by the HHE

Program to measure airborne exposures. This photo is an artistic representation that may

not be related to this Health Hazard Evaluation.
Health Hazard Evaluation Report 2015-0011-3253 Page i

We evaluated employee health concerns 

and potential worker exposure to volatile 

organic compounds and isocyanates. 

We assessed air levels of formaldehyde, 

volatile organic compounds, and 

isocyanates in the clinic and in shared 

hallways that surrounded the clinic. We 

also performed a heating, ventilation, 

and air-conditioning assessment. Our 

air samples highlighted several areas 

of the facility with formaldehyde air 

levels that approached or exceeded 

the NIOSH Recommended Exposure 

Limit. We also observed air levels within 

the clinic and shared hallways that 

suggested potential entrainment of air 

from neighboring businesses into the 

clinic. As a result of our evaluation, clinic 

management decided to relocate the 

medical clinic to another location offsite. 

Based on our findings, we recommend 

the following actions to create a more 

healthful workplace for future tenants. 

We recommend eliminating entrainment 

of air from neighboring businesses 

into the clinic, as well as follow-up 

air sampling to confirm this and that 

levels of formaldehyde in the clinic do 

not exceed the NIOSH Recommended 

Exposure Limit. 

Highlights of this Evaluation

In October 2014, the National Institute for Occupational Safety and Health (NIOSH) received 

a health hazard evaluation request from management at an outpatient medical clinic in a 

shared-use building in West Virginia. The request cited concerns about indoor air quality 

in the building. Clinic employees reported nausea, headache, dizziness, confusion, fatigue, 

burning eyes, numbness of hands and fingers, tingling around lips, metallic taste, itching, 

and reduced work productivity. As a result of our 

evaluation, the medical clinic and employees have 

been relocated to another location offsite.

What We Did

● NIOSH investigators evaluated the facility 

on March 26, 2015.

● We performed real-time air sampling 

for carbon dioxide, carbon monoxide, 

temperature, and relative humidity in 

offices, hallways, and hallways shared with 

adjacent businesses.

● We collected area air samples for 

formaldehyde, volatile organic compounds, 

and isocyanates in offices, hallways, and 

hallways shared with adjacent businesses.

● We assessed the heating, ventilating and airconditioning systems. 

● We reviewed previous indoor air 

assessments performed by private 

consultants.

● We interviewed individual employees 

by telephone to understand their health 

concerns.

What We Found

● Many employees reported respiratory and 

central nervous system symptoms that 

began on or after January 2014. Symptoms 

reported included headache; dizziness; nausea; chest pain; amnesia; difficulty breathing; 

wheeze; asthma exacerbation; isolated coughing fits at work; paresthesia (a tingling 

or pricking feeling); metallic taste in the mouth; taste disturbances; burning eyes; and 

burning throat.
Page ii Health Hazard Evaluation Report 2015-0011-3253

● We learned that previous repairs had been performed on the heating, ventilating, and 

air-conditioning system to bring the clinic into positive pressure relative to adjacent 

businesses and to seal any visible penetrations in the firewall shared between the clinic 

and the neighboring businesses.

● We verified that the clinic was under positive pressure relative to the adjacent shared 

hallway and break room between the clinic and the wood flooring shop. We found all 

five of the air-handling units and associated ductwork to be clean and well-maintained. 

All of the systems seemed to function appropriately.

● We noted that all carbon dioxide, temperature, and relative humidity measurements 

were within acceptable ranges specified for indoor working environments. 

● We found that no air samples had detectable levels of methylene biphenyl isocyanates, 

toluene diisocyanates, or hexamethylene diisocyanates. 

● The highest levels of carbon monoxide were measured external to the clinic in the 

adjacent shared hallway/break room and in the plenum space above the adjacent 

shared break room, which suggests that the carbon monoxide source is external to the 

clinic. Levels of carbon monoxide in the clinic ranged from 1-4 parts per million. No 

carbon monoxide was detected outside of the building which suggests that the carbon 

monoxide source was not from a source outside of the building. 

● We detected formaldehyde in several areas of the clinic which approached or exceeded 

0.016 parts per million, the occupational exposure limit recommended by NIOSH. 

● We measured levels of formaldehyde that were higher in areas adjacent to the clinic than 

inside of the clinic, which suggests that the source of formaldehyde is external to the 

clinic. However, because we were unable to view and survey the work being performed 

in adjacent businesses, we could not identify the source of formaldehyde.

● No detectable volatile organic compounds, other than formaldehyde, exceeded any 

Occupational Safety and Health Association, NIOSH, or American Conference 

of Governmental Industrial Hygienists exposure limits. However, we observed 

higher concentrations of many volatile organic compounds in shared hallways with 

neighboring businesses, relative to the volatile organic compound concentrations 

observed inside of the clinic which also suggests that the source of these volatile organic 

compounds is external to the clinic.

● Overall, we observed higher levels of carbon monoxide and volatile organic compounds 

outside of the clinic in shared hallways, which suggest the potential for entrainment of 

air from neighboring businesses into the clinic, despite the heating, ventilating, and airconditioning system repairs that were completed as of March 2015.

What the Building Management or Future Tenant Can Do

● Consider installing activated carbon filters in the heating, ventilating, and airconditioning systems that may lower volatile organic compound concentrations in the 

clinic. 
Health Hazard Evaluation Report 2015-0011-3253 Page iii

● Ensure that all plumbing, heating, ventilating, and air-conditioning system, and 

electrical penetrations through firewalls are sealed so the firewalls are airtight.

● Establish an anonymous environmental reporting system for staff to report buildingrelated issues.

● Building management may consider conducting air sampling in neighboring businesses 

to identify sources of air contaminants in the building.

● Establish a communication system with employees when building-related issues arise. 

Information on response actions, including exposure and environmental assessment 

reports, should be provided to employees.

What Employees Can Do

● Report new, persistent, or worsening symptoms to your personal healthcare provider 

and, as instructed by your employer, to a designated individual at your workplace. 

● Report any building-related issues by using the anonymous environmental reporting 

system.
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Health Hazard Evaluation Report 2015-0011-3253 Page v

Abbreviations

ACGIH® American Conference of Governmental Industrial Hygienists

AHU Air-handling unit

cc Cubic centimeters

CFR Code of Federal Regulations

EPA Environmental Protection Agency

°F Degrees Fahrenheit

LOD Limit of detection

HVAC Heating, ventilation, and air-conditioning

mL/min Milliliters per minute

NIOSH National Institute for Occupational Safety and Health

OSHA Occupational Safety and Health Administration

PEL Permissible exposure limit

PPE Personal protective equipment

ppm Parts per million

ppb Parts per billion

REL Recommended exposure limit

SO2 Sulfur dioxide

STEL Short-term exposure limit

TLV Threshold limit value

VOC Volatile organic compound
Health Hazard Evaluation Report 2015-0011-3253 Page 1

Summary

NIOSH received a management request to conduct a health hazard evaluation at an outpatient 

medical clinic in West Virginia. The request cited concerns about indoor air quality in the 

building. Clinic employees reported nausea, headache, dizziness, confusion, fatigue, burning 

eyes, numbness of hands and fingers, tingling around lips, metallic taste, itching, and reduced 

work productivity.

We held voluntary confidential interviews with individual employees who wished to discuss 

their symptoms and concerns in October and November 2014. We learned that employees’ 

symptoms began on or after January 2014. Additional symptoms reported by employees 

included chest pain, amnesia, difficulty breathing, wheeze, asthma exacerbation, isolated 

coughing fits at work, paresthesias (a tingling or prickling feeling), taste disturbances, and 

burning throat. Many employees reported that most symptoms resolved within 1-2 hours of 

leaving work. 

We spoke with clinic health and safety management and learned that prior to this health 

hazard evaluation request, the clinic had been closed and employees had been relocated 

to another medical center on two separate occasions. In response to employee concerns, 

air sampling surveys were performed by health and safety consultants after the clinic first 

closed. The consultants sampled for volatile organic compounds (VOCs), total particulates, 

elements and metal compounds, carbon dioxide (CO2), and carbon monoxide (CO). No air 

levels were measured above any Occupational Safety and Health Administration (OSHA), 

National Institute for Occupational Safety and Health (NIOSH), or American Conference 

of Governmental Industrial Hygienists (ACGIH) exposure limits; however, measured levels 

of VOCs and CO suggested that air was potentially being entrained from neighboring 

businesses into the clinic. As a result of the air sampling surveys, consultants recommended 

that management (1) seal openings in the firewall to reduce and eliminate air entrainment 

from neighboring businesses; (2) reopen the air intake for the clinic to allow fresh, outdoor 

air into the clinic; and (3) modify the heating, ventilating, and air-conditioning (HVAC) 

systems to ensure a positive pressurization of the clinic relative to neighboring spaces. 

Subsequently, clinic and building management made necessary repairs to implement these 

recommendations. However, when employees returned to the clinic, they continued to report 

symptoms. The clinic was closed a second time, and employees were relocated to another 

medical center off-site. Consequently, additional HVAC repairs were made and the employees 

returned to the clinic in early 2015. Despite the repairs made, employees continued to report 

respiratory and central nervous system symptoms.

During an on-site assessment of the facility in March 2015, we collected area air samples in 

offices and in hallways shared by the clinic with neighboring businesses. We measured area 

air levels of formaldehyde, CO, CO2, other VOCs, and isocyanates. We also performed an 

assessment of the HVAC systems in place.

We observed that the highest levels of CO, formaldehyde, and many other VOCs were 

external to the clinic in the adjacent shared hallway and break room and in the plenum space 

above the adjacent shared break room. Higher levels of CO, formaldehyde, and many VOCs 
Page 2 Health Hazard Evaluation Report 2015-0011-3253

in the shared hallways and plenum space suggests that the source(s) of CO, formaldehyde, 

and many other VOCs were external to the clinic. No CO was detected outside of the building 

which suggests that the CO was not from a source outside of the building. Our air samples 

highlighted several areas of the facility with formaldehyde air levels that approached or 

exceeded the NIOSH recommended exposure limit (REL). 

Our air sampling results indicated potential for entrainment of air from neighboring businesses into the clinic, despite the HVAC repairs made as of March 2015. As a result of our 

evaluation, clinic management decided to relocate the medical clinic to another location 

offsite.
Health Hazard Evaluation Report 2015-0011-3253 Page 3

Introduction

The Respiratory Health Hazard Evaluation and Technical Assistance Program received a 

management request to conduct a health hazard evaluation at an outpatient medical clinic in 

West Virginia. The request cited concerns about indoor air quality in the building. Employee 

symptoms noted in the health hazard evaluation request included nausea, headache, dizziness, 

confusion, fatigue, burning eyes, numbness of hands and fingers, tingling around lips, 

metallic taste, itching, and reduced work production. The outpatient clinic is housed in a large 

multi-use building. Other businesses that are also housed in the shared building include a 

brewing company, a wood flooring manufacturer, a metal fabrication shop, a fluorescent light 

manufacturer, and a mental health clinic. As of March 2015, approximately 15 employees 

worked at the clinic on a daily basis. The outpatient clinic has occupied a space in this 

building since January 2011.

We interviewed employees who wished to discuss their symptoms and concerns by phone in 

October and November 2014. We learned that employee symptoms began on or after January 

2014. Symptoms reported by employees included headache, dizziness, nausea, chest pain, 

amnesia, difficulty breathing, wheeze, asthma exacerbation, isolated coughing fits at work, 

paresthesias (a tingling or pricking feeling), metallic taste in the mouth, taste disturbances, 

burning eyes, and burning throat. Many employees reported that most symptoms resolved 

within 1-2 hours of leaving work. Many employees also noted that symptoms worsened 

later in the workday and/or later in the work week. Employees noted various odors on days 

that they had experienced symptoms. Specific odors reported by employees included: paint 

thinner, burning oil smell, polyurethane, and a non-specific chemical smell.

NIOSH visited the facility on March 26, 2015. During our visit, we collected area air samples 

for formaldehyde, other VOCs, and isocyanates from multiple locations within the clinic 

and in shared spaces adjacent to the clinic. Real-time monitoring devices were used to 

assess levels of CO2, CO, temperature (°F) and relative humidity within the clinic and shared 

spaces adjacent to the clinic. We also performed an assessment of the clinic’s HVAC system. 

We shared our air sampling results as well as interim recommendations in two previous 

interim reports in April and August 2014. We understand that as a result of our evaluation 

and ongoing symptoms experienced by employees, that clinic management decided to 

permanently relocate employees to another location offsite. In this report, we summarize 

the results from our air sampling and HVAC assessment in March 2015. We also provide 

additional recommendations to help protect the health of future tenants. 

Methods

Informal Employee Interviews

We asked that management inform clinic employees that they could schedule a phone call 

with the NIOSH Project Officer. Eight of the 15 clinic employees were interviewed. Employees 

shared their health concerns and were asked open-ended questions about symptom onset and 
Page 4 Health Hazard Evaluation Report 2015-0011-3253

duration, as well as any smells that were present at the onset of their symptoms. 

Formaldehyde Area Air Sampling

Silica gel tubes coated with 2,4-dinitrophenylhydrazine were used to collect area air samples 

for formaldehyde. Air samples were collected using a pump operated at 50 mL/min. Samples 

were collected and analyzed according to NIOSH Method 2016 [NIOSH 2003]. Air samples 

were collected between 10:30 A.M. and 6:00 P.M., with total sample collection time ranging 

from 5-7 hours. Area air samples were collected in the following locations: (1) midway down 

the hallway by the clinic’s mental health offices; (2) Mental Health Provider Office #17; (3) 

hallway shared by the outpatient clinic and the neighboring health clinic; (4) Exam Room 

#6; (5) RN Room #41; (6) open plenum space above the clinic hallway, near Mental Health 

Provider Office #17; (7) Exercise Room; (8) Exam Room #3; and (9) the hallway shared with 

the wood flooring manufacturer.

Volatile Organic Compound Air Sampling

We used thermal desorption tubes to collect area air samples for VOCs. Samples were 

collected according to NIOSH Method 2549 [NIOSH 1996] and analyzed for VOC content 

according to U.S. Environmental Protection Agency (EPA) analytical method TO-17 [EPA 

1999]. Air samples were collected using a pump operated at 25 mL/min. Area air samples 

were collected in the following locations: (1) hallway shared by the outpatient clinic and the 

neighboring health clinic; (2) hallway shared with the wood flooring manufacturer; (3) open 

plenum space above the clinic hallway, near Mental Health Provider Office #17; (4) Mental 

Health Provider Office #17; (5) RN Room #41; and (6) Exercise Room.

Isocyanates Air Sampling

We used ASSETTM EZ4-NCO samplers to collect area air samples for isocyanates. Samples were 

analyzed according to International Organization for Standardization (ISO) analytical method 

17734 [ISO 2013]. Air samples were collected using a pump operated at 200 (mL/min). Area 

air samples were collected in the following locations: (1) midway down the mental health 

offices’ hallway; (2) Mental Health Provider Office #17; (3) hallway shared by the outpatient 

clinic and the neighboring health clinic; (4) Exam Room #6; (5) RN Room #41; (6) open 

plenum space above the clinic hallway, near Mental Health Provider Office #17; (7) Exercise 

Room; (8) Exam Room #3; and (9) the hallway shared with the wood flooring manufacturer.

Real-time Monitoring of Carbon Dioxide, Carbon Monoxide,Temperature, and Relative 

Humidity

CO2, CO, temperature, and relative humidity measurements were taken using a VelociCalc 

Multi-Function Ventilation Meter 9555 and an Indoor Air Quality Probe 982 (TSI Inc., 

Shoreview, Minnesota). We recorded real-time measurements in clinic employees’ offices, 

clinic hallways, the plenum space above the clinic, hallways shared with neighboring 

businesses, and outside by the parking lot entrance to the clinic.

Heating, Ventilation, and Air Conditioning System Evaluation

Since a thorough HVAC Testing and Balancing had been performed throughout the clinic by 
Health Hazard Evaluation Report 2015-0011-3253 Page 5

HVAC consultants on February 5, 2015 and February 18, 2015, we did not take a complete set 

of ventilation measurements onsite. However, we did visually inspect all of the air-handling 

units (AHUs) and associated ductwork, both in the mechanical space above the clinic and 

above the drop ceiling in the clinic itself. We also took a complete set of differential pressure 

measurements between the clinic and surrounding spaces, to compare those results to the 

HVAC testing and balancing report. The differential pressure measurements were taken with 

an Energy Conservatory (Minneapolis, Minnesota) DG-500 Pressure Gauge. Measurements 

were taken across all doorways into/out of the clinic space and some in surrounding areas.

Results and Discussion 

Informal Employee Interviews

We spoke with 8 of the 15 clinic employees. We learned that employee symptoms began on or 

after January 2014. Symptoms reported by employees included headache, dizziness, nausea, 

chest pain, amnesia, difficulty breathing, wheeze, asthma exacerbation, isolated coughing 

fits at work, paresthesias (tingling or pricking sensation), metallic taste in the mouth, 

taste disturbances, burning eyes, and burning throat. Many employees reported that most 

symptoms resolved within 1-2 hours of leaving work. Many employees also noted that their 

symptoms typically worsened later in the workday and/or later in the work week.

Formaldehyde Area Air Sampling

Results from air sampling for formaldehyde are provided in Table 1. We have also provided 

the NIOSH and OSHA exposure limits, for reference. Area air levels above the NIOSH REL 

are in bold.

Table 1. Clinic air sampling results for formaldehyde, NIOSH survey, March 2015

Location Formaldehyde TWA (ppm)*

Mental Health Hallway (midway down hall) 0.017

Mental Health Provider Office #17 0.014

Hallway between clinic and other health clinic 0.022

Exam Room #6 ̶

RN 41 0.011

Open plenum/ceiling-above hallway, next to #17 ̶

Exercise Room 0.007

Exam Room #3 ̶

Shared hallway break room with wood flooring manufacturer 0.023

OSHA PEL 0.75 

NIOSH REL 0.016

ACGIH TLV 0.30

*Bolded text indicates exceedance of NIOSH REL. 

̶ Samples could not be analyzed due to pump failure.

We observed formaldehyde levels in several areas of the clinic approached or exceeded the 

NIOSH REL of 0.016 parts per million (ppm) [NIOSH 2010]. Additionally, as can be seen 
Page 6 Health Hazard Evaluation Report 2015-0011-3253

in Table 1, levels of formaldehyde were higher in hallways outside of the clinic when compared to levels observed inside of the clinic which suggests that the source of formaldehyde 

is external to the clinic. However, because we were unable to view and survey the work being 

performed in adjacent businesses, we could not identify the source of formaldehyde in the 

building. 

In the United States, occupational exposure limits have been established by Federal and State 

agencies as well as professional organizations. Some occupational exposure limits are legally 

enforceable limits; others are recommendations. The OSHA PELs are legal limits that are enforceable in workplaces covered under the Occupational Safety and Health Act. OSHA PELs 

represent the legal maximum for a time-weighted average exposure over an 8-hour work shift, 

unless otherwise noted [OSHA 2016]. NIOSH provides RELs that are time-weighted average 

concentrations that should not be exceeded over a 10-hour work shift, during a 40 hour work 

week [NIOSH 2010]. ACGIH is a professional non-profit non-governmental scientific association that reviews existing published, peer-reviewed scientific literature and publishes guidelines known as threshold limit values (TLVs®) [ACGIH 2015]. TLVs represent conditions that 

ACGIH has determined that nearly all workers may be repeatedly exposed without adverse 

health effects. The OSHA PEL is 0.75 ppm and the ACGIH TLV is 0.30 ppm for formaldehyde.

Volatile Organic Compound Air Sampling

Results from air samples collected and analyzed using thermal desorption tubes and EPA

Analytical Method TO-17 [EPA 1999] are provided in Table 2. In the table, we provide occupational exposure limits from OSHA, NIOSH, and ACGIH for various VOCs. 

No air samples for VOCs exceeded any of the OSHA, NIOSH, or ACGIH exposure limits. 

However, many of the VOCs in Table 2 affect similar organ systems and may have additive or 

synergistic effects. Where appropriate, we note the biological basis for each TLV provided in 
Health Hazard Evaluation Report 2015-0011-3253 Page 7 Table 2. Clinic air sampling results for volatile organic compounds, NIOSH survey, March of 2015. Volatile Organic Compound Analyte Hallway between clinic and mental health clinic Hallway between clinic and wood flooring shop Plenum Space, next to MH #17 Mental Health Provider Office #17 RN #41 Exercise Room Exposure Limits ACGIH TLV Basis* Acetaldehyde (ppm) ̶ ̶ ̶ ̶ ̶ 0.0051 OSHA PEL: 200 NIOSH REL: none ACGIH TLV: none ACGIH Ceiling‡: 25 Upper respiratory tract and eye irritation Sulfur Dioxide (ppm) ̶ ̶ ̶ ̶ ̶ 0.2244 OSHA PEL: 5 NIOSH REL: 2 ACGIH STEL†: 0.250 Pulmonary function and lower respiratory tract irritation Propane (ppm) 0.029 0.0229 0.0223 0.0123 0.0097 ̶ OSHA PEL: 1,000 NIOSH REL: 1,000 ACGIH TLV: none 2-methyl propane (ppm) 0.0024 ̶ ̶ ̶ ̶ ̶ OSHA PEL: none NIOSH REL: 800 ACGIH TLV: none Ethanol (ppm) 0.0243 0.0152 0.067 0.0494 0.0350 0.0173 OSHA PEL: 1,000 NIOSH REL: 1,000 ACGIH STEL: 1,000 Upper respiratory tract irritation Acetonitrile (ppm) 0.0132 0.0117 0.0117 0.058 0.0151 0.0053 OSHA PEL: 40 NIOSH REL: 20 ACGIH TLV: 20 Skin; Lower respira- tory tract irritation 2-Propanone (ac- etone) (ppm) 0.0856 0.0517 0.0537 0.0394 0.0267 0.0194 OSHA PEL: 1,000 NIOSH REL: 250 ACGIH TLV: 250 CNS Impairment; Up- per respiratory tract and eye irritation 2-Propanol (IPA) (ppm) 0.0697 0.0498 0.232 0.1659 0.1566 0.0689 OSHA PEL: 400 NIOSH REL: 400 ACGIH TLV: 200 Upper respiratory tract and eye irritation; CNS impairment
Page 8 Health Hazard Evaluation Report 2015-0011-3253 Table 2. (con’t) Clinic air sampling results for volatile organic compounds, NIOSH survey, March of 2015. Values in parts per million (ppm). Volatile Organic Compound Analyte Hallway between CBOC and Seneca Health Shared Hallway with Mountain Lumber Plenum Space, next to MH #17 Mental Health Provider Office #17 RN #41 Exercise Room Exposure Limits ACGIH TLV Basis* Acetic acid (ppm) 0.0263 0.0072 0.0219 0.0085 0.0072 0.0084 OSHA PEL: 10 NIOSH REL: 10 ACGIH TLV: 10 Upper respiratory tract and eye irritation; Pulmonary function Cyclohexane (ppm) 0.0044 - - - - - OSHA PEL: 300 NIOSH REL: 300 ACGIH TLV: 100 CNS impairment Cyclohexene (ppm) 0.0023 - - - - - OSHA PEL: 300 NIOSH REL: 300 ACGIH TLV: 300 Upper respiratory tract and eye irritation 1-methoxy-2-propa- nol (ppm) 0.0106 0.0071 0.0049 0.0026 0.0014 0.0026 OSHA PEL: none NIOSH REL: 100 ACGIH TLV: 50 Upper respiratory tract and eye irritation Hexanal (ppm) 0.0017 - 0.0011 - - - OSHA PEL: none NIOSH REL: none ACGIH TLV: none - 2-propoxy ethanol (ppm) 0.0015 - 0.00 - - - OSHA PEL: none NIOSH REL: none ACGIH TLV: none - alpha-Pinene (ppm) 0.0017 0.0013 0.0012 0.001 0.0009 0.0033 OSHA PEL: 100 NIOSH REL: 100 ACGIH TLV: none - Decamethyl cyclo- pentasiloxane (ppm) 0.0007 0.0004 0.0014 - 0.001 0.0028 OSHA PEL: none NIOSH REL: none ACGIH TLV: none -
Health Hazard Evaluation Report 2015-0011-3253 Page 9 Table 2. (con’t) Clinic air sampling results for volatile organic compounds, NIOSH survey, March of 2015. Values in parts per million (ppm). Volatile Organic Compound Analyte Hallway between CBOC and Seneca Health Shared Hallway with Mountain Lumber Plenum Space, next to MH #17 Mental Health Provider Office #17 RN #41 Exercise Room Exposure Limits ACGIH TLV Basis* Nonadecane (ppm) ̶ ̶ ̶ ̶ ̶ 0.0007 OSHA PEL: none NIOSH REL: none ACGIH TLV: none 1-methyl-2-pyrrolidi- none (ppm) ̶ ̶ ̶ ̶ ̶ 0.0026 OSHA PEL: none NIOSH REL: none ACGIH TLV: none 2-butoxyethanol (ppm) 0.1186 0.0967 0.0724 0.0419 0.0239 0.0435 OSHA PEL: 50 NIOSH REL: 5 ACGIH TLV: 20 Upper respiratory tract and eye irritation 3-Buten-2-one (methyl vinyl ketone) (ppm) ̶ 0.0022 ̶ ̶ ̶ ̶ OSHA PEL: none NIOSH REL: none ACGIH TLV: none Skin; Sensitizer; Up- per respiratory tract and eye irritation; CNS impairment Dimethyl Ether (ppm) ̶ ̶ ̶ ̶ ̶ 0.0342 OSHA PEL: none NIOSH REL: none ACGIH TLV: none *ACGIH TLV Basis Abbreviations: ‘CNS’ refers to central nervous system. ‘Skin’ indicates the potential for significant contribution to the overall expo- sure by liquid and aerosol absorption through the skin, mucous membranes, and eyes. ‘Sensitizer’ indicates the potential for an agent to produce sensitization. ‡ ACGIH Ceiling Limit is a concentration that should not be exceeded at any time during a workday. † ACGIH STEL is a 15-minute exposure level that should not be exceeded during any 15-minute period during a workday. ̶ Indicates levels that were not detectable.
Page 10 Health Hazard Evaluation Report 2015-0011-3253

We observed higher concentrations of many VOCs in shared hallways with neighboring 

businesses, relative to the VOC concentrations observed inside of the clinic. Our observation 

of higher concentrations of propane, 2-methylpropane, acetone, cyclohexane, cyclohexene, 

1-methoxy-2-propanol, 2-propoxyethanol, 2-butoxyethanol, and methyl vinyl ketone observed in shared hallways outside of the clinic suggests that the sources of these specific VOCs 

are external to the clinic. The VOCs observed with higher concentrations inside of the clinic, 

relative to levels observed in the shared hallways outside of the clinic, are commonly found in 

sanitizers (ethanol, isopropyl alcohol) and cosmetics such as deodorants, sunscreens or hair 

spray (decamethylcyclopentasiloxane).

Some VOCs were observed only in the exercise room. Because we were unable to view and 

survey the work being performed in adjacent businesses, we cannot explain the observation of 

acetaldehyde, sulfur dioxide, nonadecane, decanal, 1-methyl-2-pyrrolidinone, and dimethyl 

ether only in the exercise room. We could not identify any obvious source of these specific 

VOCs in the exercise room. Most of the VOCs observed only in the exercise room were 

observed at low levels ranging from 0.0007-0.0342 ppm. However, sulfur dioxide (SO2) levels 

approached the ACGIH STEL of 0.250 ppm [ACGIH 2015]. An ACGIH STEL is a 15-minute 

exposure level that should not be exceeded during any 15-minute period during a workday. 

The 0.224 ppm SO2 concentration observed in the exercise room is notable because the EPA 

has established a 1-hour standard of 0.075 ppm because of the respiratory effects associated 

with SO2 exposure [EPA 2011]. Although the EPA National Ambient Air Quality Standards 

cannot be applied directly to a workplace setting, we note that the SO2 levels measured in the 

exercise room exceeded the air standard that the EPA has established to protect the health 

and welfare of the public. SO2 in the exercise room may contribute to bronchoconstriction 

and increased asthma symptoms [EPA 2015]. Further, because breathing rates increase during 

exercise, any respiratory effects caused by SO2 exposure may be exacerbated when exercising.

Isocyanates Air Sampling

We analyzed air samples for the most commonly used isocyanates in industry and found that 

no air samples had detectable levels. More specifically, no air samples had detectable levels of 

methylene biphenyl isocyanates, toluene diisocyanates, or hexamethylene diisocyanates.

Real-time Monitoring of CO2, CO,temperature, and relative humidity

We noted that all CO2, temperature, and relative humidity measurements were within acceptable ranges specified for indoor working environments [ASHRAE 2013]. ASHRAE notes in 

their ANSI/ASHRAE Standard 62.1-2016: Ventilation for Acceptable Indoor Air Quality that 

indoor CO2 concentrations no greater than 700 ppm above outdoor CO2 concentrations will 

satisfy a substantial majority (about 80%) of occupants [ANSI/ASHRAE 2016]. Since outdoor 

CO2 concentrations usually range between 375 to 500 ppm, indoor concentrations below 1200 

ppm would be sufficient for most occupants. Additionally, assuming slow air movement (less 

than 40 feet per minute) and 50% indoor relative humidity, the operative temperatures recommended by ASHRAE range from 68.5o

F to 75oF in the winter, and from 75oF to 80.5oF in the 

summer. The difference in temperature ranges between the seasons is largely due to clothing 

selection. ASHRAE also recommends that indoor relative humidity be maintained at or below 
Health Hazard Evaluation Report 2015-0011-3253 Page 11

65% [ANSI/ASHRAE 2013].

We observed CO at levels that ranged from 1-4 ppm in the clinic. We measured CO levels of 

approximately 4 ppm in the plenum space above the clinic. The OSHA PEL for occupational 

exposure to CO is 50 ppm [29 CFR 1910.1000], and the NIOSH REL is 35 ppm [NIOSH 

2010]. We noted that OSHA and NIOSH exposure limits are based upon a time-weighted 

average for an entire workday and that we only collected short-term measurements for CO 

in various locations in the clinic. Since we collected repeated measurements throughout the 

workday and observed levels no greater than 4 ppm in the clinic, we believe the likelihood 

that CO levels in the clinic exceed the time-weighted average OSHA PEL or NIOSH REL is 

low. However, the OSHA and NIOSH limits are designed for occupational exposure measurements in manufacturing and other trades that have potential sources of CO (e.g., vehicle 

exhaust, diesel engine exhaust, welding). Typical levels of CO in offices are between 0-5 ppm 

[Illinois Department of Public Health 2011]. Average CO levels found in a study of six office 

buildings located in the United States ranged from 1-1.5 ppm [Reynolds et al. 2001]. Another 

study of 56 European office buildings reported average CO levels that ranged from 0.5-1.9 

ppm [Bluyssen et al. 1996].

The highest levels of CO were measured external to the clinic in the adjacent shared hallway/

break room (6-10 ppm) and in the plenum space above the adjacent shared break room (14-

17 ppm), which suggests that the CO source is external to the clinic. Additionally, we noted 

that the plenum space above the clinic and above the adjacent shared break room is separated 

by a drywall firewall which may not be airtight. However, we were unable to view the entirety 

of the firewall that separates the two plenum spaces and conduct tracer gas testing to identify 

potential penetrations in the firewall. No CO was detected outside of the building which suggests that the CO source was not from an outdoor source. We were informed by clinic staff 

and management that propane-powered forklifts were used in an adjacent business, and we 

noted that propane-powered forklifts can generate CO. However, we were unable to view all 

processes in operation in adjacent businesses and many combustion processes are known to 

generate CO. We could not confirm that the propane-powered forklifts were the only possible 

source of CO in the building and in the clinic.

Heating, Ventilation, and Air Conditioning System Evaluation

All of the AHUs and associated ductwork appeared to be in good working order and well 

maintained. We did not find any supply vents disconnected from ductwork or obvious kinks 

in flexible duct runs. This was not surprising given the service and HVAC testing and balancing work done on the systems in the two months prior to our arrival.

The differential pressure measurements taken during the NIOSH visit are presented in Table 

3. We took measurements at two different times, once when the AHU serving the break room 

(AHU-6) was off and again when AHU-6 was on. Our differential pressure measurements, 

as well as those taken by the HVAC consultants on February 18, 2015, can be seen in Table 3. 

This comparison is only made to show that differential pressure differences can be significantly affected by many factors, including outside weather conditions and open doors and windows in surrounding businesses. During the NIOSH visit, it was cool, rainy, and extremely 
Page 12 Health Hazard Evaluation Report 2015-0011-3253

windy outside and the wood flooring manufacturer was operating with their large overhead 

garage door open. The conditions on the day of our visit may have differed from the conditions on the days when the previous HVAC consultants conducted their measurements.

Table 3. Differential pressure measurements, NIOSH survey, March 2015. Values in inches of water. 

Location HVAC Consultant 

February 18, 2015

NIOSH 

March 26, 2015 

(with AHU6 OFF)

NIOSH

March 26, 2015 

(with AHU6 ON)

Main front door from outside 

into vestibule

-0.0020 

(into vestibule)

+0.0095 

(out from inside)

+0.0095 

(out from inside)

Inner vestibule door to waiting room -0.0122 Neutral Neutral

Outer door to loading dock -0.0257 +0.0038 +0.0038

North end of corridor between clinics to outside-0.0220

 (in from outside)

+0.0150

 (out from inside)

+0.0150

 (out from inside)

Northern door from corridor 

into clinic -0.0019 -0.0015 -0.0015

Central door from corridor 

into clinic -0.0027 +0.0010 +0.0010

West clinic door into breakroom (from Home-Based 

Primary Care Offices)

Did not measure +0.0010

 (into breakroom) +0.0045

Center clinic door into breakroom (between Provider Office #17 and Exam Room #6)

+0.0035

 (into breakroom)

+0.0015 

(into breakroom)

+0.0050 

(into breakroom)

East clinic door into breakroom (beside Exam Room 

#5)

Did not measure +0.0015 

(into break room)

+0.0050 

(into breakroom)

Corridor door into breakroom -0.0056 Neutral Neutral

Door at south end of corridor 

to Adjacent Wood Flooring 

Business

+0.0020 

(into adjacent business)

-0.0080

 (into corridor)

-0.0080 

(into corridor)

Air flows between adjacent areas of a building are similar to air flows due to weather patterns 

outside; air always flows from areas of higher pressure to areas of lower pressure. When an 

area is under negative pressure to its surroundings, it means that air flows from the surroundings into the negative pressure space. On the other hand, an area under positive pressure 

pushes air out into the surroundings. The previous HVAC consultants found the clinic space 

under negative pressure to the surrounding areas, with the one exception where the clinic 

space was found to be under positive pressure to the adjacent breakroom. The long corridor 

between the two clinics in the building was under positive pressure to the breakroom and to 

the wood flooring manufacturer. Thus, air from outside the building and from the long corridor between clinics was being pulled into the clinic on February 18, 2015. Air from the corridor was being pushed into the break room and into the space occupied by the wood flooring 

manufacturer.

In comparison, on March 26, 2015, the clinic was mainly positive to the surrounding areas, 
Health Hazard Evaluation Report 2015-0011-3253 Page 13

which is the more preferred condition. The clinic was positive to the break room when AHU6 was off, and even more positive when AHU-6 was operational. The one exception was that 

the clinic was negative to the long hallway at the northern door. The long hallway was neutral 

(neither positive nor negative) to the break room, but slightly negative to the wood floor manufacturer at the southern door. Our observations of higher concentrations of contaminants 

in the hallway, relative to the clinic, may have been due to air flowing out of the wood flooring manufacturer into the corridor. Because air from the corridor was being pulled into the 

clinic at the northern door, and could pass across the neutral door into the breakroom, there 

is a potential pathway for contaminants into the open plenum space above. AHU-3, AHU-4, 

and AHU-5 all share the air in the plenum space, thus, these contaminants could have been 

redistributed throughout the clinic space as air is recirculated. Although these pressure differentials are not conclusive proof that contaminants are entering the clinic from surrounding 

businesses in the same building, they do provide some evidence that a contaminant pathway 

is possible given certain outdoor environmental conditions and operating conditions within 

surrounding areas and businesses. 

Conclusions 

Employees reported histories of central nervous system and respiratory symptoms that began on or after January of 2014. Symptoms reported by employees included headache, dizziness, nausea, chest pain, amnesia, difficulty breathing, wheeze, asthma exacerbation, isolated 

coughing fits at work, paresthesias, metallic taste in the mouth, taste disturbances, burning 

eyes, and burning throat. Many employees also noted that their symptoms typically worsened 

later in the workday and/or later in the workweek and typically resolved with time away from 

work.

We observed formaldehyde levels in several areas of the clinic that approached or exceeded 

0.016 ppm, the occupational exposure limit recommended by NIOSH [NIOSH 2010]. We 

note that NIOSH RELs are specified for personal air samples whereby a sample would be 

collected by hanging sampling equipment on the worker and collecting a sample from their 

breathing zone for the majority of their workday. In short, area samples cannot be used for 

legal enforcement. However, area samples can indicate areas with higher risks of exposure. No 

air samples for any of the detected VOCs exceeded any U.S. occupational exposure limits. No 

air samples had detectable levels of methylene biphenyl isocyanates, toluene diisocyanates, or 

hexamethylene diisocyanates.

We observed higher area concentrations of CO, formaldehyde, and many VOCs in shared 

hallways with neighboring businesses, relative to the CO, formaldehyde, and VOC concentrations observed inside of the clinic. Our observation of higher concentrations of CO, formaldehyde, and many VOCs observed in shared hallways outside of the clinic suggests that the 

sources of these gases and vapors are external to the clinic. Our air sampling results indicate 

the potential for entrainment of air from neighboring businesses into the clinic, despite the 

HVAC repairs made as of March 2015.
Page 14 Health Hazard Evaluation Report 2015-0011-3253

Recommendations 

We understand that as a result of our evaluation, clinic management decided to relocate the 

medical clinic to another location offsite. Based on our findings, we recommend the actions 

listed below to create a more healthful workplace for future tenants.

Our recommendations are based on an approach known as the hierarchy of controls. This 

approach groups actions by how effective they are at removing or reducing hazards. In most 

cases, the primary approach is to eliminate hazardous materials or processes, and to install 

engineering controls to reduce exposure or shield employees. Administrative measures and 

personal protective equipment may be needed until such engineering controls are in place, or 

if engineering controls are not effective or feasible. 

Engineering Controls 

Engineering controls can reduce employees’ exposures by removing the hazard from the 

process or by placing a barrier between the hazard and the employee. Engineering controls 

protect employees effectively without placing primary responsibility of implementation on the 

employee. 

1. Ensure that the clinic remains under positive pressure in relation to adjacent 

businesses. Install monitors in the walls of the clinic to monitor pressurization in the 

clinic.

2. Install and maintain activated carbon filters in the HVAC systems to reduce VOC 

concentrations in the clinic. 

3. Ensure that firewalls between the clinic and adjacent businesses are as airtight as 

possible.

Administrative Controls 

Administrative controls refer to employer-dictated work practices and policies to reduce or 

prevent hazardous exposures. Their effectiveness depends on employer commitment and employee acceptance. Regular monitoring and reinforcement are necessary to ensure that policies and procedures are followed consistently.

1. Establish an anonymous environmental reporting system for staff to report buildingrelated issues.

2. Building management may consider conducting air sampling in neighboring 

businesses to identify sources of air contaminants in the building.

3. Establish a communication system with employees when building-related issues arise. 

Information on response actions, including exposure and environmental assessment 

reports, should be provided to employees.
Health Hazard Evaluation Report 2015-0011-3253 Page 15

4. Employees should report new, persistent, or worsening symptoms to their personal 

healthcare provider and, as instructed by their employer, to a designated individual at 

their workplace. An individualized management plan (such as assigning an affected 

employee to a different work location) is sometimes required, as indicated by medical 

findings and recommendations of the physician. Employees with symptoms should 

provide their personal physicians or other healthcare providers with a copy of this 

report.
Page 16 Health Hazard Evaluation Report 2015-0011-3253

References

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and BEIs®. Cincinnati, OH: ACGIH Signature Publications.

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analytical methods (NMAM). 4th ed. Schlecht PC, O’Connor PF, eds. Cincinnati, OH: U.S. 

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Health Hazard Evaluation Report 2015-0011-3253 Page 19

Keywords: NAICS 622110 General Medical and Surgical Hospitals, respiratory, sensory, 

indoor air quality, IEQ, volatile organic compounds, carbon monoxide
Page 20 Health Hazard Evaluation Report 2015-0011-3253

The Health Hazard Evaluation Program investigates possible health hazards in the workplace 

under the authority of the Occupational Safety and Health Act of 1970 (29 U.S.C. § 669(a)

(6)). The Health Hazard Evaluation Program also provides, upon request, technical assistance 

to federal, state, and local agencies to invest igate occupational health hazards and to prevent 

occupational disease or injury. Regulations guiding the Program can be found in Title 42, Code 

of Federal Regulations, Part 85; Requests for Health Hazard Evaluations (42 CPR Part 85).

Disclaimer 

The recommendations in this report are made on the basis of the findings at the workplace 

evaluated and may not be applicable to other workplaces.

Mention of any company or product in this report does not constitute endorsement by the 

National Institute for Occupational Safety and Health (NIOSH).

Citations to Web sites external to NlOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. NIOSH is not responsible for the 

content of these Web sites. All Web addresses referenced in this document were accessible as 

of the publication date.

Acknowledgments

Desktop Publisher: Tia McClelland

NIOSH Laboratory Assistance: Ryan LeBouf

Site Visit: Brie Hawley, Steve Martin, Chris Mugford, and Randy Boylstein.

Availability of Report

Copies of this report have been sent to the employer, employees, and union at the 

facility. The state and local health department and the Occupational Safety and Health 

Administration Regional Office have also received a copy. This report is not copyrighted and 

may be freely reproduced.

This report is available at http://www.cdc.gov/niosh/hhe/reports/pdfs/2015-0011-.pdf.

All other HHE Reports may be found at http://www2a.cdc.gov/hhe/search.asp. 

Recommended citation for this report:

NIOSH [2016]. Evaluation of indoor air quality concerns at an outpatient 

medical clinic in a shared use building – West Virginia. By Hawley B, Martin 

S, Mugford C, and Boylstein R. Morgantown, WV: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and Health, NIOSH HETA No. 2015-0011-

3253.
To receive documents or other information about

occupational safety and health topics, contact NIOSH

Telephone: 1-800-CDC-INFO (1-800-232-4636)

TTY: 1-888-232-6348

email: cdcinfo@cdc.gov

or visit the NIOSH website at http://www.cdc.gov/niosh

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