NITROGEN-DIOXIDE, THE OXIDES OF NITROGEN, AND INFANTS HEALTH SYMPTOMS

In this cross-sectional postal study, the authors measured nitrogen di oxide levels inside infants' bedrooms and outside their homes. During the 2-wk monitoring period, the authors investigated the association b etween nitrogen dioxide levels and 20 infant symptoms. The subjects we re 1 200 women who had infants aged 3-12 mo. Median levels of indoor a nd outdoor nitrogen dioxide were 6.8 and 12.6 ppb, respectively. Envir onmental factors that were associated significantly with indoor levels were gas cooking, cigarette smoking, reported traffic levels, and pre sence of a kerosene heater; use of a cooker hood was associated negati vely with indoor nitrogen dioxide levels. There was no evidence for an y short-term significant association between prevalence of respiratory symptoms and nitrogen dioxide levels. Diarrhea, the only symptom asso ciated significantly and positively with indoor nitrogen dioxide level s, had unadjusted and adjusted odds ratios of 1.48 (95% confidence int erval: 1.13, 1.95) and 1.38 (1.11, 1.70), respectively. This associati on is discussed in terms of a proposed mechanism with nitric oxide. No association between a gas cooker in the home and diarrhea was found. The association between diarrhea and nitrogen dioxide level might have been a chance finding; the authors investigated 20 symptoms, and at l east 1 was expected to be significant at the .05 level. The finding, h owever, was similar to that reported in a previous study in which a ga s cooker was a proxy for nitrogen dioxide exposure.