The term “healthcare facility” describes many settings. Medical centers, acute-care hospitals, surgery centers, long-term care facilities, urgent-care centers, medical office buildings, doctors’ offices, hospice care, outpatient clinics—each of these structures has a distinct construction, use, and occupancy, and each generates its share of IEQ complaints. This article discusses the unique challenges industrial hygienists face when they conduct IEQ investigations in healthcare facilities. These challenges include a wide range of affected populations and a variety of possible sources for IEQ problems. In addition, many of the hazards in these facilities may be unfamiliar t​o investigators used to working in environments more traditionally frequented by IHs. THE INVESTIGATION As with all industrial hygiene assessments, the investigation of an IEQ complaint in a healthcare facility generally includes the following steps:
  • characteriz​ing the complaint through questionnaires, incident logs, employee interviews, medical evaluations, review of prior environmental reports or sampling data
  • visually inspecting the site: evaluating the space and/or HVAC system
  • identifying potential indoor and outdoor sources: chemical (for example, formaldehyde or xylene), biological (mold, bacteria), and physical (noise/vibration, lighting, ergonomics)
  • sampling or monitoring of potential sources and interpretation of results
  • developing solutions: elimination, substitution, engineering and administrative controls
Each step can increase in complexity depending on the nature of the complaint and phase of the investigation. POPULATIONS In any IEQ investigation, it is important to understand the affected population when designing an assessment strategy. Different populations will have different sensitivities and risk tolerances. They may have language barriers, and they may respond differently to certain communication styles. Participation from the following populations is often critical to the success of an investigation in a healthcare facility:
Medical/clinical staff. The educational backgrounds within this group, which includes physicians, nurses, and medical assistants, can vary widely. These professionals can be hard to meet with or to engage in the investigation due to scheduling and the nature of their work. Communicating with those who are knowledgeable about health effects may be difficult for IH investigators used to dealing with the general public.
Engineering/facilities staff. These individuals are the most knowledgeable about the general mechanics of the building. They can help the investigator identify source pathways and HVAC system deficiencies.
Environmental services staff (EVS). Responsible for disposal of waste (including bio-hazardous waste) and the cleaning and disinfection of surfaces, EVS staff are usually the most knowledgeable about the types of cleaning products used on site.
Administrative staff. These staff typically work in office settings and on the business side of the medical center. They may provide valuable information in the early stages of the investigation regarding the nature of the IEQ concerns, including the locations, times, and dates of complaints.
Patients. This group includes individuals of all ages, races, and educational backgrounds. Some sensitive populations may be included in this group, such as infants, the elderly, immunocompromised individuals, and cancer patients. Occupational exposure limits and guidelines are not appropriate for evaluating risk to patients. While they may not be directly involved in the investigation, it’s important to understand the potential effects on patients when drawing conclusions or making recommendations.
Vendors, consultants, and contractors. Although this group might lack proper training and understanding of unique healthcare issues, they are often knowledgeable about the use of chemicals, sources of noise, or building performance characteristics.
Communication is often a key component to resolving IEQ complaints, and this is especially true in healthcare settings. Although these groups typically work within the same facility, communication between them is often inconsistent, inaccurate, or incomplete.

IEQ Investigations in Healthcare Facilities

IEQ investigations benefit greatly from a multidisciplinary team approach to solving problems. The team may include individuals from the populations listed above, with the exception of patients. Interested stakeholders can identify and evaluate risks while the investigator capitalizes on their knowledge. For example, clinicians may provide information regarding the specific symptoms experienced by the employees who initiated the complaint, and facilities staff can explain HVAC design and maintenance protocols. An effective team typically includes staff from the affected department, capital improvements, facilities, leadership, union representatives, and outside contractors. ENVIRONMENT Healthcare facilities have complex HVAC systems to satisfy complex design requirements and keep employees, visitors, and patients comfortable and safe. Improper design and maintenance of HVAC systems is one the most important contributors to IEQ complaints. One function of the HVAC system is to remove, control, or dilute contaminants specific to healthcare settings, such as:
  • hazardous drugs (for example, antineoplastic agents)
  • waste anesthetic gases (nitrous oxide, halogenated anesthetics)
  • surgical smoke (volatile organic compounds, bioaerosols, dead and live cellular material, viruses)
  • chemicals such as formaldehyde, xylenes, alcohol, reagents, and dyes
  • aerosolized drugs (respiratory therapy nebulizers, pharmaceutical powders)
  • cleaners, disinfectants, and sterilizing agents (bleach, ortho-phthalaldehyde, alcohols, quatanery ammonia, glutaraldehyde, or hydrogen peroxide/peroxyacetic acid)
  • infectious agents
Outdoor sources of pollutants—such as loading docks, ambulance drop offs, helipads, and landscaping operations—can also contribute to IEQ complaints and should be included in any assessment.
The highly engineered spaces in healthcare settings are intended to maintain sterile areas and control hazards from infectious patients. Temperature and relative humidity control is important for comfort and controlling the spread of airborne viruses. Viruses such as the flu may survive longer and be more easily transmitted during periods of low relative humidity. To ensure that potential pathways are not overlooked or misinterpreted, investigators assessing the HVAC system need to understand the design requirements specific to healthcare settings, such as air exchange rates, which vary by room function; positive and negative pressure differentials; air filter efficiency ratings; exhaust systems; and specialty containment systems.
Several organizations and regulatory bodies have developed standards and guidelines for the design and maintenance of the HVAC system in healthcare facilities. Some notable reference documents include the Facilities Guidelines Institute (FGI) Guidelines for Design and Construction of Hospitals and Outpatient Facilities; ASHRAE Standards 55, 62, 170, and 180, among others; and various state-regulated mechanical codes. These documents provide specific design requirements based on occupancy and room function.
When assessing a facility, it is important to have a basic understanding of these current standards and guidelines, along with the facility’s own internal expectations and policies. It is not uncommon for areas within a facility to be out of compliance or performing in conformance to the code that was in place at the time of construction.
HVAC systems in healthcare facilities generally run continuously. The limited ability to shut down these critical systems can lead to extended maintenance cycles and make repairs difficult. Dirty coils, standing water in condensate pans (and resulting biofilm), and dust accumulation on insulation can lead to amplification of microorganisms. High MERV-value filtration may become overloaded, causing excessive pressure drops, damage to filters’ frames, and bypassing of filter media. CHEMICAL IEQ ISSUES Due to specialized work activities, patient procedures, and the need for frequent high-level cleaning and disinfection, the use of chemicals is common in healthcare settings. These chemicals present occupational exposure challenges and may also contribute to IEQ complaints in the form of unwanted odors or reported health impacts such as skin, eye, and respiratory irritation.
Interpretation of sample data is often a challenging aspect of IEQ assessments, particularly when the investigation is within a healthcare facility. Occupational exposure limits such as OSHA PELs and ACGIH TLVs are generally inappropriate in the context of an IEQ investigation.
More appropriate evaluation criteria may include environmental reference levels. These non-occupational or environmental exposure limits are generally intended for a broader range of individuals, including susceptible or non-healthy people with continuous/chronic or short-term/acute exposure. When evaluating IEQ exposure data, it is not uncommon to compare sample results to the lowest available health risk-based environmental reference levels. Environmental reference levels include national, international, and regional guidelines such as:
  • EPA Regional Cancer and Non-Cancer Screening Levels for Air
  • California Office of Environmental Health Hazard Assessment (OEHHA) Non-Cancer Reference Exposure Levels
  • New York State Department of Public Health “Guidance for Evaluating Soil Vapor Intrusion in the State of New York” Air Guideline Values Table 3.1 (2006)
  • New Jersey Department of Environmental Protection Generic Vapor Intrusion Screening Levels – Tables 1-3
Other health-based screening levels developed for vapor intrusion assessments may also be used as reference levels.
Comparing data to background levels may also be appropriate. Examples of notable reference publications include EPA’s “Background Indoor Air Concentrations of Volatile Organic Compounds in North American Residences (1990–2005): A Compilation of Statistics for Assessing Vapor Intrusion” and Lawrence Berkeley National Laboratory’s “Volatile Organic Compounds in Indoor Air: A Review of Concentrations Measured in North America since 1990.”
Concentrations represented in environmental reference levels are more conservative than occupational exposure limits due to the large margins of safety used to calculate them. These margins of safety account for populations that are most sensitive to exposure or subject to longer exposure periods and may be more appropriate for evaluating risk to the populations found in healthcare settings. Prior to using any environmental or background reference levels, the hygienist should understand how the numbers were derived and their limitations. BIOLOGICAL IEQ ISSUES Healthcare facilities house a variety of biological agents, including mold, waterborne pathogens such as legionella, viruses, and bacteria. As in other types of buildings, one of the most common sources of IEQ complaints in healthcare facilities is water damage and resulting mold growth. If not handled appropriately, disturbance of mold growth can present an increased risk of hospital-acquired infections at surgical sites for immunocompromised individuals. For this reason and for consistency with CDC guidelines, it may be necessary to employ analytical techniques to collect and analyze mold growth and airborne mold spores to the species level. Historically this has meant culturable analysis (often at body temperature) and turnaround times of 7 to 14 days; however, faster turnaround times are now achieved through use of polymerase chain reaction (PCR) techniques. PHYSICAL HAZARDS AND IEQ ISSUES
Healthcare facilities typically house areas that contain physical hazards such as radiation sources, but these areas are required to be appropriately labeled and access is generally limited. Other physical hazards, such as unwanted noise, vibration, and temperature extremes, may contribute to IEQ issues. If temperature and humidity in a building leads to thermal discomfort, occupants may express dissatisfaction with IEQ quality. Thermal discomfort may also exacerbate symptoms.
Various organizations have developed recommended temperature ranges based on occupancy and room function. These recommendations are intended to satisfy the majority of building occupants, not the most sensitive individuals. Temperature and humidity control is also important for controlling the growth and spread of microorganisms.
As with evaluation criteria for chemical exposures, occupational exposure limits are not always appropriate when dealing with physical hazards in healthcare facilities. For example, comparing noise levels measured in a neonatal intensive care unit to OSHA PELs or ACGIH TLVs would not be appropriate given the clinical needs of that space. It may be necessary for the multidisciplinary team to research and develop levels appropriate for a given clinical requirement. CONSTRUCTION AND IEQ Construction and renovation projects can affect IEQ by introducing dust, noise, vibrations, and outside personnel that lead to complaints or disrupt clinical operations. Vibrations from earth moving or jack hammering, even from great distances, can release otherwise stable contaminants or affect sensitive equipment or procedures. It is not uncommon for renovation activities to uncover water damage and mold growth, which, if not handled correctly, may contribute to IEQ complaints or patient infections. PROTECT YOURSELF While most of us are comfortable wearing steel-toed boots and hard hats, we might not be as comfortable with scrubs and hair covers. Investigators working in healthcare facilities should be trained to anticipate and recognize hazards to which they may be exposed, including bloodborne pathogens, hazardous materials, and sharps. Protective clothing is generally required when entering sterile areas or areas known or suspected to have patients with an illness easily transmitted by direct contact or by indirect contact with items in the patient’s environment.
It is not uncommon to be surrounded by contaminated instruments and surfaces, hazardous drugs, sharps or patients with infectious diseases. Investigators must break the habit of touching surfaces or thoughtlessly laying down clipboards or equipment. Before entering a facility, contractors will often be required to show proof of vaccination or resistance to common infectious dieses and may be required to register with a third-party verification service.
As an expert in the anticipation, recognition, evaluation, and control of hazards, the investigating IH must be cognizant of hazards that may be present, processes and chemicals used, and how systems move utilities throughout the building. Personal protection should always be considered, and investigators should work with appropriate healthcare facility staff to ensure they are properly trained and vaccinated. David Brinkerhoff, CIH, is director of the Forensic Analytical Consulting Services, Inc. Sacramento regional office. He can be reached at (916) 726-1303 or dbrinkerhoff@forensi Michelle Rosales, MPH, CIH, is a senior project manager of the Forensic Analytical Consulting Services, Inc. Los Angeles regional office. She can be reached at (310) 668-5617 or
ASHRAE: Indoor Air Quality Guide, Best Practices for Design, Construction, and Commissioning (2009).
California Office of Environmental Health Hazard Assessment (OEHHA) Non-Cancer Reference Exposure Levels.
CDC: Workplace Safety and Health Topics, Indoor Environmental Quality.
The Facility Guidelines Institute (FGI): Guidelines for Design and Construction in Health Care Facilities (2014).
The Joint Commission: Accreditation Program: Hospital Environment of Care (2015).
Lawrence Berkeley National Laboratory, Indoor Environment Department, Environmental energy Technologies Division. “Volatile Organic Compounds in Indoor Air: A Review of Concentrations Measured in North America since 1990” (2003).
New Jersey Department of Environmental Protection Generic Vapor Intrusion Screening Levels – Tables 1-3.
New York State Department of Public Health “Guidance for Evaluating Soil Vapor Intrusion in the State of New York” Air Guideline Values Table 3.1 (2006).
It is not uncommon to be surrounded by contaminated instruments and surfaces, hazardous drugs,
sharps or patients with infectious diseases.
Click or tap icon to read case studies.
From Hardhats to Hair Covers​​
Case Studies IEQ investigations in healthcare facilities can yield some surprising results, as the following examples suggest. ​CASE 1: EXHAUST—BUT FROM WHERE? Patients and employees at a large medical facility had made several odor complaints, which they attributed to helicopter exhaust during helicopter landings. It was initially assumed that the helicopter exhaust was being entrained into the facility via the outdoor air intakes. However, following air sampling at strategic locations, the pathway was identified as the elevator shaft. Understanding the HVAC system and evaluating all suspected pathways, coupled with air sampling, assisted in determining the source and appropriate controls. ​ CASE 2: ARE THE FILTERS THE PROBLEM? Operating room staff expressed concerns about odor and particulate related to a nearby wildfire and their effects on patients undergoing surgical procedures. Facilities staff reported that HEPA filters were used in the HVAC system serving the ORs, but particle counts were higher than would be expected in an area with high level filtration. Further investigation determined that the filters actually had a lower MERV value than staff was aware of and that particulate counts in the ORs were consistent with expected percent reductions for that level of filtration. Determining that the filtration system was functioning as designed allowed clinical staff to make informed decisions about potential risk to patients. CASE 3: ODORS IN THE LAB Employees working in a clinical laboratory had complained of odor and irritation associated with working in the laboratory. During an investigation it was observed that the door to an adjacent pathology laboratory was consistently propped open. Manometer readings and visual indicators confirmed that the pathology laboratory was positively pressurized relative to the clinical laboratory, therefore causing the entrainment of odors into the adjacent laboratory. Additionally, hazardous waste containers were consistently left open and specimen grossing was observed to be completed on a bench top without local exhaust ventilation. Various administrative controls (keeping the door closed, closing all waste containers) and engineering controls (use of local exhaust at the bench top) were recommended to reduce the entrainment of odors into the adjacent clinical laboratory.