While researchers estimate that the average person spends 90 percent of his or her life indoors, government has been slow to establish specific standards governing levels of indoor air pollutants. With a few exceptions, science has yet to convince lawmakers that indoor air contaminants cause specific health problems that demand legislation. The management of indoor air quality (IAQ) remains primarily a private, not public, concern.

Nonetheless, IAQ is an important issue for building owners and operators. Poor indoor air quality can impair human health, harm productivity, disrupt business processes and lead to costly litigation. Some voluntary standards are in place. Standards developed by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) have been codified in some jurisdictions. The American Conference of Governmental Industrial Hygienists (ACGIH) has developed guidelines for permissible levels of airborne materials in an indoor environment.

Need for information

The unformed state of IAQ regulations does not diminish the need to obtain accurate air quality diagnostic information. Facts, in the form of accurate air quality data, provide the most realistic basis for management decisions on IAQ. Without facts, managers are left with only impression and guesswork to go on — hardly a sound foundation for action.

Specific numbers on the cost of poor IAQ are elusive, but the stakes can be very high. The American Lung Association reports that in 1998, there were an estimated 17,315 lung cancer deaths attributable to inhalation of carcinogens in the workplace. On the manufacturing floor, contaminated air can disrupt processes and bring production lines to a stop. The stringent procedures companies and workers follow to ensure air quality in so-called “clean rooms,” where the fabrication of silicon integrated circuits takes place, show how vital pristine air quality is for some manufacturers.

While official government IAQ standards in the United States are limited, one exception to the lack of standards can be found in the industrial workplace. OSHA has set limits on human exposure to a long list of air contaminants (Standard 1910-1000) and established standards for ventilation and respiratory protection in certain high-hazard occupations, such as abrasive blasting, grinding, polishing and spray finishing operations. OSHA Standard 1910.94 for general industry governs ventilation and respiratory protection in abrasive blasting, grinding, polishing and spray finishing operations. OSHA Standard 1926.57 regulates similar activities in the construction industry.

Many factors involved

Exactly what do we mean by indoor air quality? In some instances, the quality problem may not be the air at all. As OSHA stated in a 1994 rulemaking proposal, “other physical factors such as lack of windows, noise and inadequate lighting, and ergonomic factors involving uncomfortable furniture and intensive use of video display units, etc., will cause discomfort in occupants that may be inaccurately attributed to air quality.”

NIOSH prefers to use the term “Indoor Environmental Quality” (IEQ). This can be a somewhat broader concept than IAQ, and can include factors other than air quality.

According to NIOSH, “Indoor environmental contaminants can originate within the building or be drawn in from outdoors. If contaminant concentrations are excessive, IEQ problems can arise, even if the HVAC system is properly designed and well-maintained. NIOSH investigators have found IEQ problems caused by ventilation system deficiencies, overcrowding, out-gassing from materials in the office and mechanical equipment, tobacco smoke, microbiological contamination, and outside air pollutants.”

Though neither could be considered a pollutant, humidity and temperature are important comfort factors, and failure to manage them can lead to other IAQ problems. Excessive humidity, for instance, can encourage the growth of mold.

Common indoor air contaminants include tobacco smoke; biological agents such as animal dander, bacteria and mold; airborne particulates, including asbestos; volatile organic compounds like glue, solvents and cleaning agents; carbon dioxide and carbon monoxide; radioactive radon gas; and pesticides. Sources may include people and pets; industrial processes; furniture coatings and paint; construction materials and flooring; printing processes; carpet, draperies and fabrics; motor vehicles; and more.

Many of these contaminants are present in small amounts in most indoor environments without causing IAQ problems. When concentrations or combinations of pollutants rise excessively, however, IAQ deteriorates and occupants can begin to experience symptoms.

Table 1 lists common indicators of unsatisfactory IAQ, the root causes and remedies.

Table 1. Air Quality Problems, Causes and Cures

Common causes

IAQ diagnosis and remediation can pose significant challenges, because the contaminants are normally invisible, and because problems can stem from one or more of a variety of causes. Among them:
  • Poor design of buildings and HVAC systems. Building and system design and air conditioning/ventilation performance are crucial factors in providing indoor air quality. An air intake placed above a loading dock could draw in vehicle exhaust and distribute carbon monoxide, oxides of nitrogen and diesel soot to every cubicle. Systems without sufficient fresh air exchange can allow contaminants such as CO2 and volatile organic compounds to build up.
    Failure to engineer and size systems to meet requirements means they will never perform to satisfactory levels. Choosing the wrong construction and interior finishing materials, or using materials incorrectly, can lead to chemical emissions that damage IAQ.
  • Improper system operation. Air pressure, temperature, humidity and operating cycles must all be properly adjusted to balance operating efficiency with the comfort of building occupants. Minimizing operating time by leaving systems off until occupants arrive in the morning might save money, but could allow airborne pollutants to build up during off hours.
    Building occupants play a role as well. Occupants who close off HVAC supply or return ducts, or manipulate system controls may cut off needed air exchange. Failure to properly separate office spaces from a shop floor could allow shop contaminants to affect the entire workplace.
  • Inadequate maintenance. Even the best building and HVAC designs will not deliver the required results if electrical systems or vents fail, fan and compressor motors malfunction, or controls fail to accurately regulate the system. Filter maintenance programs are essential to ensure complex HVAC systems deliver the IAQ results they are designed to produce.
  • Failure to monitor and act on IAQ issues. For the employer, every worker has the potential to serve as the canary in the corporate coal mine. But clearly, waiting until employees complain before addressing indoor air quality is akin to planning a sprinkler system after the fire trucks arrive. Too little, too late.
By assessing IAQ on a planned basis, carefully operating and maintaining HVAC systems, controlling contaminant sources and acting swiftly to resolve any IAQ issues, employers and managers can maintain productivity, and head off personnel problems and questions of legal liability that might arise from deficient indoor air quality.

Address the issues

Preventing IAQ issues from developing is clearly the most efficient and least costly approach to air quality maintenance. A program of air quality monitoring, conducted on a consistent schedule, provides assurance that air quality remains at desired levels. And monitoring provides a clear indication to employees that management takes the issue of IAQ seriously.

In addition, if air quality indicators start to deviate from desired levels, regular monitoring gives the maintenance team or industrial hygienist the best chance to intervene early and correct the problem before business activities and building occupants are affected.

Such a program should include monitoring of temperature, humidity, CO and CO2, particulate levels and ventilation system airflow.

But prevention is not always possible. When IAQ issues arise, a structured approach is required to quickly identify the real root cause and produce a satisfactory solution.

The intelligent use of precision test and measurement equipment is an important part of the process. Following is a list of steps management can take to monitor indoor air quality and mitigate problems that arise.
  • Conduct a survey of credible staff
    - Who is bothered by IAQ problems?
    - Where do they experience these problems, and when?
    - What symptoms do they experience?
  • Take a building history
    - When was it constructed? Were there delays in construction?
    - What is the history of building remodels?
    - Is there a history of damage and subsequent repair?
    - What maintenance practices are followed?
  • Perform a physical inspection
    - What can you see? Smell? Hear?
    - What is the moisture level in materials and various locations?
  • Make air quality measurements
    - Temperature, humidity, CO2, CO, percent of outside air
    - Air velocity and flow
    - TICs, volatile organic compounds, mVOCs
    - Particulates
  • Sample air and surfaces for biological contaminants
    - Counts and identification of fungi and bacteria

Get the facts

Indoor air quality has arisen as a significant issue for building owners and operators, HVAC engineers and technicians, certified industrial hygienists, remediation professionals, and building occupants. The potential costs of indoor air problems, in lost productivity, human suffering, process disruption and possible litigation, are too high to ignore.

For those managing building operations, accurate measurement is the key to maintaining IAQ to meet or exceed desired levels. Similarly, measurement is a critical step in identifying the causes of IAQ problems, developing a solution and verifying its effectiveness.

Only measurement, performed by trained professionals using instruments of unquestioned accuracy, can move the diagnosis and remediation of air quality problems from a realm of feelings, impressions and emotions to the world of verifiable facts and actions based on science.