It is estimated that people spend at least 90 percent of their lives indoors. Much of this indoor time may be spent working inside of an airtight office building without operable windows, where exposure to air pollutants is significantly greater as compared to being outdoors.
Over the past several decades, office buildings have become increasingly airtight in order to maximize comfort and improve energy efficiency through central heating and cooling systems. But this effort has also translated into little control of one's physical environment, and ongoing exposure to potential allergens and materials used in such things as carpeting, furniture, printers, etc., and components of the building itself.
In the 1970s, the term "sick building syndrome" was coined to describe collective symptoms experienced by people working in the same environment, typically an office building. These workers would complain of symptoms such as fatigue, headaches, eye, nose or throat irritation, and sensitivity to odors not linked to any specific disorder other than time spent in the building. The World Health Organization suggested that up to 30 percent of new or remodeled buildings worldwide have sick-building complaints.
Although data is not always sufficient to make a conclusive link between symptoms and time spent in the building, some potential causes for the syndrome are thought to be due to inadequate ventilation -- combustion pollutants such as carbon monoxide from malfunctioning heating systems, or the release of volatile organic compounds (VOCs) from elements such as formaldehyde, which can be found in some carpet backings, resin finishes, and many other indoor materials or equipment. VOC levels may be up to 10 times higher indoors than outdoors.
The Environmental Protection Agency (EPA) cites exposure to indoor pollutants in home and work environments as an "often overlooked" public health issue, and one that is estimated to cause thousands of cancer deaths and hundreds of thousands of respiratory health problems in both children and adults every year. They have called for a "Healthy Buildings Healthy People" initiative (www.epa.gov/iaq/pubs/hbhp.html) in the 21st century to promote improved ventilation systems, materials and products.
With the advent of the green movement and LEED (Leadership in Energy & Environmental Design) certification, buildings are rapidly becoming "healthier." LEED recently certified its 12,000th commercial project that incorporates LEED standards for energy and water conservation, and promotion of indoor environmental quality, among other requirements.
Ironically, although many historic buildings have inadequate insulation and need to become more energy efficient, many already incorporate health-friendly features such as natural ventilation and light, and have greater cubic feet per minute (cfm) of outside air for each building occupant.
Building ventilation standards of the early to mid-1900s called for 15 cubic feet per minute of outside air for each occupant. With the oil embargo of 1973 and spurred efforts to conserve energy, these standards were reduced to five cfms per building occupant, thereby increasing indoor pollution. The cfm ventilation standard was recently revised upwards by the American Society of Heating, Refrigerating and Air-Conditioning Engineers to a minimum of 15 cfms per person, and 20 cfms in office spaces.
Alan Hedge, Ph.D., is a professor in the Department of Design and Environmental Analysis at Cornell University, and director of the Human Factors and Ergonomics Laboratory (http://ergo.human.cornell.edu). He is co-author of "Keeping Buildings Healthy," and some of his research interests include the effect of indoor air quality relative to sick-building-syndrome complaints among office workers, and the effects of office lighting on eyestrain among computer workers.
Q: How do you define a "healthy" building?
A: It's a building in which people do not report any health problems associated with the building, and where they feel comfortable.
Q: What environmental variables within a building can make a person sick, and what are some of the most common scenarios?
A: Typically, it would be dampness and dirtiness that allow the growth of gram-negative bacteria and toxic molds in building materials and inside the air ducts and air handling units of the HVAC (heating, ventilation and air conditioning) system; emissions of irritating and toxic volatile organic compounds from building materials, paints, furniture, and some technologies; allergens in the dust in buildings; dangerous gases, such as carbon monoxide and radon; and cigarette smoke.
Q: Is quality of air the most important environmental variable to consider when working in a building?
A: Yes, from a health standpoint. And from a comfort standpoint, temperature is the most important variable.
Q: What improvements have been made over the past several decades in terms of healthy buildings?
A: The LEED rating system of the U.S. Green Building Council to encourage low-emission buildings with good indoor air quality; Greenguard certification of building materials and furniture to ensure low-emitting products; low-emission, water-based paints and adhesives; low-emission technologies (computers, photocopiers); better ventilation system designs; better air filtration to remove particles; duct cleaning and better interior cleaning; no smoking; low- or no-fragrance policies; and better cleaning and removal of allergens (cat, dog, dust mite, cockroach, mouse, etc.).
Q: Can a building be sensitive to a worker's overall health, and what might we see in the future?
A: Yes, we'll see continued improvements in low-emissions building materials, furniture, furnishings, and technologies; better air filtration technologies both inside HVAC systems and in desktop units; better HVAC designs allowing more individual control over ventilation; and more expansive LEED credits for healthy buildings.