Indoor Human Health Risks:
The EPA's Vision for the 21st Century

REUTERS - The Environmental Protection Agency 's Draft Final Report," Healthy Buildings, Healthy People: A Vision for the 21st Century " is a call to action for us all to work together to improve the indoor environment. The risks associated with poor indoor air quality—asthma, cancer, reproductive and development problems, and other health effects—are explained in the following Chapter 1 of the Report.


An estimated 27 million Americans suffer from asthma (U.S. EPA 1999). In addition, about 5,000 deaths occur yearly from asthma—an increase of 33 percent in the last decade (Mannino et al. 1998). Consequently, the social and economic costs are large. Among chronic diseases, asthma is the number one cause of absenteeism from school (Pope et al. 1993). Asthma cost an estimated $6.2 billion in the United States in 1990, including direct medical and indirect non-medical costs combined. An update of this figure would fall in the range of $7 to $9 billion in 1998 dollars (Weiss et al. 1992).

Some groups in this country (e.g., children, certain minorities, seniors, and low-income, urban populations) are disproportionately affected by asthma. An estimated 1.8 million people required emergency room services for asthma in 1995. Mortality rates associated with asthma among African-Americans, as a whole, are two- to three-fold higher than those among whites. Mortality rates for African-American children are fivefold higher than those for their white peers (Mannino et al. 1998). While research has not yet explained the rise in the incidence of asthma, nor all the reasons why individuals first contract it, there is general agreement that controlling indoor exposures is an important protective measure (NAS 2000).

Recently the National Academy of Sciences/Institute of Medicine issued a report on asthma and indoor air quality, confirming that dust mites and other allergens, microorganisms, and some chemicals found indoors are triggers for asthma. In addition, the report stated there was sufficient evidence regarding associations between ETS, in preschool-aged children, and house dust mites and the development of asthma (NAS 2000). ETS may significantly aggravate symptoms of asthma for 200,000 children and may affect as many as 1,000,000 children to some extent (U.S. EPA 1992).


A number of indoor contaminants, such as asbestos, radon, tobacco smoke, and benzene, are known human carcinogens. Other indoor contaminants, such as certain chlorinated solvents, polycyclic aromatic hydrocarbons, aldehydes, and pesticides, are considered likely to cause cancer in humans.

The National Academy of Sciences, in its latest report on radon health science (NAS 1998), concluded that radon is the second leading cause of lung cancer in the country. NAS has estimated that about 12 percent of the lung cancer deaths in the United States are linked to radon. They calculate the number of lung cancer cases attributable to radon exposure to range from 15,000 to 22,000 annually.

Environmental tobacco smoke is estimated to cause an additional 3,000 lung cancer deaths in nonsmokers each year (U.S. EPA 1992). Other forms of cancer have also been found to be associated with indoor pollutants (e.g., leukemia with benzene; bladder cancer with ETS).

Reproductive and Developmental Effects

During the period 1991 to 1994, almost 900,000 children had elevated blood levels, which can cause a variety of developmental delays, including effects on intelligence quotient (IQ); vision, hearing and stature deficits; and learning disabilities (U.S. DHHS 1997a). Several studies indicate that common indoor pollutants such as lead and ETS can also impair fetal development. A California report estimates that 9,700 to 18,600 cases of low birth weight in infants are caused each year by ETS (NCI 1999).

Many other environmental agents, including a number of chemicals commonly found indoors (e.g., tobacco smoke, some pesticides, lead and other heavy metals, alcohols, and plastic additives), are suspected of causing developmental toxicity in humans (U.S. EPA 1991a, NCI 1999). Endocrine disruptors (e.g., certain pesticides and plasticizers), which affect the normal function of sex and thyroid hormones, present a new area of concern for reproductive toxicity. Adverse effects on a developing child may result from exposure prior to conception in either parent, exposure during pregnancy, or post-natal exposure. These effects range from low birth weight to genetic diseases to lower IQs and infertility.

While the proportion of reproductive and developmental effects due to indoor environmental factors is currently unknown, the impact could be serious. Approximately 3 percent of newborn children have one or more significant malformations at birth. By age one, about 3 percent more are recognized to have serious developmental defects. Lifetime health-care costs for children born each year with birth defects are estimated to be more than $8 billion.

Other Health Effects

Indoor environments can cause or amplify many other health effects as well. The American Heart Association estimates that 35,000 to 40,000 cardiovascular deaths per year among nonsmokers can be attributed to ETS exposure (Taylor et al. 1991). Recent studies have shown that, compared to those who had not been exposed, ETS was associated with a 20 percent increase in the progression of atherosclerosis (hardening of the arteries) (Howard et al. 1998). Carbon monoxide (CO) poising associated with the improper use and maintenance of fuel-burning appliances kills more than 200 people per year in this country and results in about 10,000 admissions to hospital emergency rooms for treatment (U.S. CPSC 1997). An additional 600 to 700 accidental deaths from CO poisoning occur indoors from other sources, including automobiles (Cobb and Etzel 1991). The agent for Legionnaires' disease, a potentially deadly pneumonia which affects 10,000 to15, 000 people each year, is associated with cooling systems, whirlpool baths, humidifiers, food market vegetable misters, and other indoor sources, including residential tap water (EPA et al. 1994; U.S. DHHS 1997b). Effects associated with toxins from indoor fungi and bacteria range from short-term irritation to immunosuppression and cancer (EPA et al. 1994).

Studies show that symptoms of sick building syndrome (SBS) may be caused or intensified by indoor environmental problems (U.S. EPA 1991b, U.S. EPA et al. 1994). The term "sick building syndrome," first employed in the 1970s, described a spectrum of specific and nonspecific complaints reported by a population of building occupants. These symptoms can be associated with their presence in the building. These complaints may also result from causes other than SBS, including illness contracted outside the building, acute sensitivity (e.g., allergies), job-related stress or dissatisfaction, and other factors. Data are insufficient to thoroughly evaluate many SBS problems.


United States Environmental Protection Agency, Office of Air and Radiation, EPA Report 402-K-00-002, March 2000

Source: Aerias: Better Heath Through Indoor Air Quality Awareness

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