Public health: Quality of indoor residential air and health

About 90% of our time is spent indoors where we are exposed to chemical and biological contaminants and possibly to carcinogens. These agents may influence the risk of developing nonspecific respiratory and neurologic symptoms, allergies, asthma and lung cancer. We review the sources, health effects and control strategies for several of these agents. There are conflicting data about indoor allergens. Early exposure may increase or may decrease the risk of future sensitization. Reports of indoor moulds or dampness or both are consistently associated with increased respiratory symptoms but causality has not been established. After cigarette smoking, exposure to environmental tobacco smoke and radon are the most common causes of lung cancer. Homeowners can improve the air quality in their homes, often with relatively simple measures, which should provide health benefits.In North America, adults spend about 87% of their time in buildings, 6% in vehicles and 7% outdoors.¹ Leech and colleagues² have reported that Canadians spend similar amounts of time indoors. Typically, more time is spent indoors in very hot or cold climates. As a result, personal exposure to airborne substances is more closely related to indoor rather than outdoor pollution.^3,4 We review the sources, health effects and control strategies for several of the most important sources of residential biological and chemical contaminants.Although outdoor and indoor environments tend to be viewed as distinct entities, some outdoor pollutants enter the home. However, less air pollution enters tightly sealed homes, such as those found in colder and hotter climates where windows and doors are more regularly closed to retain conditioned air.⁵ In addition, economically disadvantaged families may be more likely than others to live close to roadways and industry, have lower-quality housing and have less access to air conditioning, which may result in poor indoor air quality.⁶ On days with high concentrations of particulate matter, cities with a high prevalence of air conditioner use report fewer hospital admissions for cardiovascular disease, chronic obstructive pulmonary disease and pneumonia compared with cities with lower air conditioner use.⁵Indoor air pollutants include carcinogens and biological and chemical contaminants. The latter category can be divided into combustion products and gases released from indoor materials (off-gassing emissions). Several guidelines for exposure limits for indoor air contaminents have been developed by the Canadian government (Open in a separate window