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Association of indoor nitrogen dioxide with respiratory symptoms and pulmonary function in children
L M Neas1, D W Dockery, J H Ware
1Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115.
Insights
Indoor nitrogen dioxide exposure increases children's risk of respiratory symptoms. A 15-ppb rise in nitrogen dioxide was linked to more frequent symptoms, with girls showing a stronger association.
Area of Science:
- Environmental Health
- Pediatric Respiratory Medicine
- Epidemiology
Background:
- Indoor air quality is a significant factor in children's health.
- Nitrogen dioxide (NO2) is a common indoor air pollutant linked to respiratory issues.
Purpose of the Study:
- To investigate the association between indoor nitrogen dioxide levels and respiratory symptoms in children.
- To assess the impact of NO2 on pulmonary function in a pediatric cohort.
Main Methods:
- A cohort of 1,567 children (aged 7-11) in six US cities were monitored for indoor nitrogen dioxide.
- Week-long NO2 measurements were taken in winter and summer.
- Logistic regression analyzed symptom reports and NO2 concentrations.
Main Results:
- A 15-ppb increase in annual average indoor NO2 was associated with a 40% increased incidence of lower respiratory symptoms (OR=1.4).
- Girls exhibited a stronger association between NO2 exposure and symptoms (OR=1.7) compared to boys (OR=1.2).
- No consistent effect of NO2 on pulmonary function was observed.
Conclusions:
- Indoor nitrogen dioxide exposure is a significant risk factor for cumulative respiratory symptoms in children.
- The findings highlight the need for strategies to reduce indoor NO2 to protect pediatric respiratory health.
Abstract:
The effect of indoor nitrogen dioxide on the cumulative incidence of respiratory symptoms and pulmonary function level was studied in a cohort of 1,567 white children aged 7-11 years examined in six US cities from 1983 through 1988. Week-long measurements of nitrogen dioxide were obtained at three indoor locations over 2 consecutive weeks in both the winter and the summer months. The household annual average nitrogen dioxide concentration was modeled as a continuous variable and as four ordered categories. Multiple logistic regression analysis of symptom reports from a questionnaire administered after indoor monitoring showed that a 15-ppb increase in the household annual nitrogen dioxide mean was associated with an increased cumulative incidence of lower respiratory symptoms (odds ratio (OR) = 1.4, 95% confidence interval (95% Cl) 1.1-1.7). The response variable indicated the report of one or more of the following symptoms: attacks of shortness of breath with wheeze, chronic wheeze, chronic cough, chronic phlegm, or bronchitis. Girls showed a stronger association (OR = 1.7, 95% Cl 1.3-2.2) than did boys (OR = 1.2, 95% Cl 0.9-1.5). An analysis of pulmonary function measurements showed no consistent effect of nitrogen dioxide. These results are consistent with earlier reports based on categorical indicators of household nitrogen dioxide sources and provide a more specific association with nitrogen dioxide as measured in children's homes.