Indoor Air Quality

Indoor air quality in ECU’s buildings is a major area of interest for Environmental Health and Safety. Most of our faculty, staff and students spend near 90% of their time indoors. Therefore it is important that EH&S respond to reports of poor indoor air. While most of our buildings do not have indoor air problems, any building can experience events of poor air quality.

Indoor Air Quality is not a specific entity but a vague term used to describe several variables measurable in the indoor air and how they relate to the occupants’ comfort and health. In general, we measure carbon dioxide, relative humidity, temperature and sometimes carbon monoxide. Even with scientific measurements, a proper assessment cannot be made without conducting a site survey to identify visible problems in the suspect building such as excess dust, mold growth, condition of the heating and ventilating system, indoor/outdoor sources of air contaminants, construction/renovation, occupant load, etc. Additional testing may be necessary should the initial assessment indicate the need and/or additional sources of suspect chemicals be found. When considered together, all of these variables can give an indication of the quality of the air in a specific building. It is important to note that some variables, for example carbon monoxide, may exist above a comfort level or even an OSHA determined permissible exposure level and the occupants may not notice any discomfort or ill effects. Likewise, conditions of little health effect may cause great discomfort, such as ninety-degree temperature in an office, and cause the perception of an uncomfortable or bad environment. All variables must be considered together and established tolerances must be examined to properly access the IAQ of a building.

Finally, there are some conditions that can cause IAQ like discomfort but are mistakenly associated with the air quality. These can individually and in combination contribute to a perception that the indoor air quality is poor. For an example, an office worker may experience headaches fairly routinely. These headaches may be caused from inappropriate or inadequate lighting, glare, stress, a too bright or too dim computer screen, noise, presbyopia, a sinus cold, ergonomics or a variety of other external and physiological/psychosocial sources not involved with indoor air. Likewise, dry, scratchy and/or watery eyes might be caused not by the air quality but by excessive air movement, cosmetics, excessive computer use, life changes, stress and other stressors. While it is important to consider IAQ as a member of the list of air quality related symptoms, it should not be viewed as the only possible cause of these vague and varied symptoms.

To understand these variables and conditions better, we will look at each a little closer.

Comfort Level

The comfort level is a range of indoor air parameters that most people will perceive as comfortable. It is neither a danger level nor a level mandated by a regulatory agency. It is used as a guideline for occupant comfort only. For example, EPA recommends indoor air temperatures be maintained between 73.5° F and 79.5° F for occupant comfort. We know that temperatures outside this range are not dangerous as many people work outside or in specialty occupations that require them to labor in temperatures in the 90 – 100° F range in the summer or 50 – 30° F or colder in the winter. Obviously, one needs to dress appropriately but these temperatures are not dangerous if proper precautions are taken. Just as with temperatures, most indoor air contaminants have safe levels. Carbon dioxide is found naturally outside at about 400 ppm. The American Society for Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) recommends indoor air levels be maintained at or bellow 1000 ppm as a comfort level. OSHA standards allow workers to work in environments where carbon dioxide levels reach 5000 ppm and submariners often work in environments of 10,000 ppm. But for most people, around 1000 ppm is comfortable and is the level we aim for to provide occupant comfort.

Carbon Dioxide (CO2)

Carbon dioxide exists as a normal constituent of outside air and is commonly measured outside between 350 and 400 parts per million (ppm). Its source inside is most often the people who occupy the building although other sources such as flame combustion sources can also contribute to CO2 levels in indoor air. As part of normal respiration, we inhale air to obtain oxygen and exhale carbon dioxide. Therefore, the more people you have in a given area, like a classroom, the more carbon dioxide will accumulate unless it is exchanged with outside air provided by the heating, ventilation and air conditioning (HVAC) system. As the carbon dioxide level rises, some people will start to notice changes in the “feel” of the room air. The room will start to feel stuffy, closed in and uncomfortable. Individuals may experience difficulty concentrating, become drowsy or even experience a slight headache. These reactions are commonly experienced as the carbon dioxide exceeds the 1000 ppm comfort level. Carbon dioxide is not regulated until it reaches 5000 ppm which is the level OSHA has set as allowable for a worker to be exposed to for up to eight hours a day. Even with our tight buildings, it is highly unlikely that the carbon dioxide level would ever approach the OSHA PEL. Our goal, however, is to maintain our buildings below the comfort level. This way, we can provide a comfortable environment that is more productive and healthy.

Carbon monoxide (CO)

Carbon monoxide is a dangerous, odorless indoor air contaminant. When elevated levels are found in an indoor environment, it is most often caused by a combustion source that is not operating properly. Faulty gas heaters and automobile exhaust are most often cited as the source of these gases. Health effects of carbon monoxide exposure include headaches, dizziness, nausea, faintness, and, at high levels, it can cause death. OSHA allows workers to work in an environment with up to 50 PPM CO. Due to the heavy automobile traffic around campus, short-term peeks of 4 to 7 PPM CO is not uncommon in university buildings and in most cases we see less than 2 PPM average over a twenty four hour period. Although there is no action level set by OSHA or ASHRAE, our office begins an investigation should the average levels of carbon monoxide measure above 2.5 PPM in an indoor environment. While dangerous levels of carbon monoxide have never been found at ECU, we measure for carbon monoxide as a precaution. To prevent dangerous build up of carbon monoxide indoors, absolutely no flame combustion sources, other than those designed for and installed as part of the facilities construction, are authorized to be used inside university buildings.

Relative Humidity (RH)

Relative Humidity (RH) is the amount of moisture being held as water vapor in the air. When the air is too dry, below 20% RH, people become uncomfortable and may experience dry skin and respiratory irritation, dry, irritated eyes especially with contact users. When the RH is too high, (above 70%), mold and mildew may start to grow on organic materials including ceilings, wall, desks etc. The spores released from the mold and mildew can cause respiratory irritation or trigger allergy symptoms. We generally aim for a relative humidity of between 30% and 60% as an acceptable level. It is important to note that the humidity of outside air can affect the humidity of inside air and building occupants may need to provide dehumidifiers to control excessive humidity levels during certain seasons of the year.

Temperature (°F)

As all of us know, temperature is the measure of heat or cold in a given environment. Its importance is that of comfort more so than health. EPA and the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) have established a range of temperatures that seems comfortable for most people. It is at the temperature extremes that a health problems such as heat exhaustion and hypothermia occur. Keep in mind, that temperatures above 85° F may be uncomfortable but are not necessarily a health problem as people routinely work safely outside in 100° F+ temperatures.

One additional note; ECU does not allow space heaters to be used in its buildings. Beside the obvious fire hazard, space heaters disrupt the proper functioning of the buildings heating system. Using a space heater artificially heats a room. This in turn sends a signal through the thermostat to the heating system that heat is not needed. While the employee using the space heater may find their own area comfortable, coworkers will find their respective work area uncomfortably cool.

Volatile Organic Compounds (VOC)

Volatile Organic Compounds (VOC) refers to a large family of organic vapors that can pollute the indoor air. Our concern about VOC comes from animal toxicity studies where animals have been exposed to VOC’s over long periods or in high concentrations. A few of these compounds have been implicated as carcinogens but no direct evidence links these to chronic health effects due to indoor environments. The most common symptom to VOC exposure is irritation of the eyes and upper respiratory track. Exposure to higher levels VOC may cause headaches, loss of coordination, nausea, and damage to liver, kidney, and central nervous system.

Sources of VOCs include new building materials, some cleaning agents, paints, adhesives, cosmetics, consumer products and indoor combustion sources. Some commonly found VOC’s in indoor environments include formaldehyde, acetone, mineral spirits, petroleum distillates etc. When new, building materials sometimes off-gas small amounts of VOC until the gases have dissipated out of the material. This off-gassing is temporary and can be controlled by increasing the fresh air into the building to dilute VOCs.

Sampling for VOC is complex and highly specific as any building, new or old, will have some VOCs present. Investigations of elevated VOC’s are based of specific symptomology as identified by the occupant’s physician.

How You Can Improve IAQ

The occupants themselves have caused many of the indoor air complaints and odor complaints we have investigated. Some investigations have found mold growing in and around over-watered plants. In other situations, excessive use of window air conditioners have caused moisture to condense on walls an furniture creating conditions mold found favorable for growth. Still others have been caused by activities such as taping plastic over air supply vents to reduce airflow to a room. In all of these cases, the occupant thought they were making their environment better when in fact, they were creating the right situations for their own discomfort.

To avoid being the cause of your own Indoor Air problem, make sure you and all around you know and follow these easy rules:

  • Don’t block the buildings air vents or HVAC grills – Call Facilities Services to adjust the flow.
  • Adhere to ECU’s smoking policy – if you must smoke, please smoke outside.
  • Don’t over water plants – artificial plants need less care and don’t grow mold as easily.
  • Clean up spills immediately – the longer they stay, the more insects they attract.
  • Dispose of garbage and food trash promptly and properly – trash is a frequent cause of odor and attracts insects.
  • Be frugal with perfumes and cologne – some people may be allergic to certain perfumes and colognes.
  • Understand and utilize proper procedures when handling chemicals – follow ECU’s Chemical Hygiene Program.
  • Notify your supervisor or Facilities Services if you discover a roof leak or other leak – these are a common cause of mold growth within a building.
  • Notify your supervisor if you suspect your building is having an indoor air problem – EH&S will investigate to see if the potential for an IAQ exists and if found EH&S will work with Facilities Services to resolve the issue.

Performance Targets For Good IAQ

Air ComponentMaximum Comfort LevelMaximum OSHA Permissible Exposure level
Carbon Dioxide700 PPM above ambient5000 PPM
Carbon MonoxideNone set50 PPM
Temperature73.5° F to 79.5° FNo established limits
Humidity30% to 60%No established limits
Volatile Organic CarbonChemical Specific: 1/10 TLVChemical Specific: 1/10 TLV


EH&S investigates all indoor air complaints. Investigations will generally follow the following format.

  • Interview the person lodging the complaint for specific information on their discomfort.
  • Conduct a walk through inspection of the facility to identify obvious caused for the complaint.
  • Assess the HVAC system for obvious causes for the complaint.
  • Conduct IAQ monitoring is symptoms indicate possible air source.
  • Involve Facilities services for thorough inspection of the HVAC system and repair, if need.
  • Involve Prospective Health if health treatment or epidemiological assessment is needed.
  • Consult with Biological Safety if biologicals are suspected as a source.
  • Work through the appropriate department to effect correction of any deficiencies or problems with the building environment.
  • Provide and explain the data obtained during the investigation to the affected personnel and draft a final report if necessary.
  • Conduct a follow up assessment if indicated by the situation.