Nitrogen dioxide and respiratory infection: pilot investigations

Laboratory and human studies have raised concern that exposure to nitrogen dioxide may increase the frequency and severity of respiratory infections in children and adults. Cooking with a natural-gas-fueled stove exposes a home's residents to short-term peaks of nitrogen oxides and to higher average levels of nitrogen oxides than are measured in homes with electric stoves. We have designed a longitudinal study of infants to determine if nitrogen dioxide exposure from cooking stoves increases the incidence or severity of respiratory infections during the first 18 months of life. Pilot investigations for the longitudinal study were conducted from 1984 through 1986. This report provides the results of the pilot investigations. The first study, conducted in 1984 and 1985, was designed to document (1) that appropriate subjects could be recruited; (2) that nitrogen dioxide concentrations in Albuquerque homes were in the range of interest; (3) that an infant's personal exposure to nitrogen dioxide could be estimated; and (4) that a valid, feasible approach for surveillance could be implemented. To accomplish these goals, the families of infants were recruited at two Albuquerque hospitals, and their homes were monitored for nitrogen dioxide using a passive sampling tube. With this approach, we successfully recruited 147 households; monitoring for nitrogen dioxide showed substantially higher levels in homes with gas stoves than in homes with electric stoves, as previously found in other U.S. cities. More detailed investigations in a sample of the homes showed that personal exposures of the infants, who did not attend day care, could be satisfactorily estimated by room concentrations. We also demonstrated that mothers would complete a daily calendar-diary on respiratory symptoms and provide information every two weeks on illnesses occurring since the previous surveillance call. The second pilot study, conducted in 1986, was designed to refine the system for illness surveillance. Additional goals were to test further the methods for exposure assessment and to evaluate recruitment of subjects through pediatric practices. We recruited 75 infants and followed them over a four-month period. Information from the surveillance system was compared with the clinical assessments of the project's nurse practitioner and the subjects' physicians, and with the results of viral cultures. We also evaluated biweekly versus weekly surveillance calls. Overall, the results of the second pilot study documented that a surveillance system for respiratory illness that incorporates calendar-diaries and biweekly telephone calls is a feasible, relatively unbiased, and sensitive method for studying respiratory illness in a large population of infants. We also found that subjects could be successfully recruited through a pediatric practice.(ABSTRACT TRUNCATED AT 400 WORDS)