Indoor Environmental Quality Related to Occupant Satisfaction and Performance in LEED-certified Buildings

Indoor air is a dominant exposure for humans. More that half of the body's intake during a lifetime is air inhaled in the home. Thus, most illnesses related to environmental exposures stem from indoor air exposure. Indoor air was believed to be a major environmental factor for more than a hundred years, from the start of the hygienic revolution, around 1850, until outdoor environmental issues entered the scene, and became dominant around 1960. Main environmental issues today are outdoor air quality, energy use, and sustainable buildings, but not indoor air quality (IAQ). But, there is mounting evidence that exposure to IAQ is the cause of excessive morbidity and mortality. In developing regions indoor unvented burning of biomass for cooking is the cause of at least 2,000,000 deaths a year (mainly women and children), and in the developed world IAQ is a main cause of allergies, other hypersensitivity reactions, airway infections, and cancers. Cancer of the lungs is related to indoor radon and ETS exposure. Allergies, airway infections and sick building syndrome are associated with, e.g., "dampness", a low ventilation rate, and plasticizers. In the future more emphasis must be given to IAQ and health issues. Indoor air quality plays a major role with regard to public health. The main problems are in the developing countries with the indoor burning of biomass for cooking and heating. The solution is a stove with a chimney. In developed regions, good ventilation, getting rid of "dampness" problems, and adequate testing of new building materials would reduce morbidity and mortality.

Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P = 0.04) and significantly lower levels of reported effort (p = 0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P = 0.003), typing 6.5% less text than when the pollution source was absent from the office Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.