Since the early 1970s, the health effects of indoor air pollution have been investigated with increasing intensity. Consequently, a large body of literature is now available on diverse aspects of indoor air pollution: sources, concentrations, health effects, engineering, and policy. This review begins with a review of the principal pollutants found in indoor environments and their sources. Subsequently, exposure to indoor air pollutants and health effects are considered, with an emphasis on those indoor air quality problems of greatest concern at present: passive exposure to tobacco smoke, nitrogen dioxide from gas-fueled cooking stoves, formaldehyde exposure, radon daughter exposure, and the diverse health problems encountered by workers in newer sealed office buildings. The review concludes by briefly addressing assessment of indoor air quality, control technology, research needs, and clinical implications.

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We prospectively assessed the relations between various characteristics of day care and lower respiratory illness (LRI) in a cohort of 1,268 Minnesotan children, born between October 1989 and January 1991 and followed to 2 yr of age. Information on LRI was abstracted from medical records and data on day care use, respiratory symptoms, and physician diagnosis of asthma were obtained from questionnaires. We identified a subgroup of 60 children with recurrent wheezing illnesses. The LRI rate ratio for day care attendance was 2.0 (95% confidence interval = 1.7, 2.2). Rate ratios were similar regardless of the day care setting, number of other children present, or the number of hours spent in day care. A parental history of asthma further increased the rate ratio for day care attendance. Day care attendance was associated with a threefold risk of having recurrent wheezing illnesses. We conclude that day care attendance is an important risk factor for LRI in young children, and for recurrent wheezing illnesses.

The relations among three methods of measuring exposure to environmental tobacco smoke, questionnaires, urinary cotinine, and a passive monitor for ambient nicotine, were investigated in a study of 48 children in Minnesota in 1989. Subjects were all under 2 years of age and did not attend day care. Passive nicotine monitors were placed in the activity room and the child's bedroom for 1 week, urine samples were collected at the beginning and end of the week for cotinine analysis, and a detailed questionnaire concerning cigarette smoking was administered at the end of the week. These same measures were obtained weekly for 8 weeks for 22 of the children. Among households with smokers, concentrations of ambient nicotine and urinary cotinine were lowest when the father smoked, intermediate when the mother smoked, and highest when both parents smoked. Activity room concentrations were highly correlated with both urinary cotinine (r = 0.81) and the total number of cigarettes smoked in the house (r = 0.86). Regression equations indicated that knowing who smoked in the house was a more important predictor of ambient nicotine than knowing the amount smoked. Both urinary cotinine and ambient nicotine demonstrated variability over time, although ambient nicotine was less variable. In addition, 100% of possible ambient nicotine samples were collected in contrast to 80% of urine samples. The results of the study suggest that both urinary cotinine and ambient nicotine provide better information about the exposure of young children to environmental tobacco smoke than questionnaire data alone, and that ambient nicotine may be the more useful in this population based on its greater stability and ease of collection.

Patterns of alcohol consumption were assessed in 12,440 pregnant women interviewed at the time of delivery. Only 92 women (0