A Comparison of Continuous and Passive Personal Monitoring Techniques to Assess Nitrogen Dioxide Exposure from Indoor Combustion Sources

Twenty preschool children from the Frank Porter Graham Child Care Center, and their mothers, were monitored for NO2 exposure in their homes and at the day care center. Subjects were monitored for one week during the summer and winter months using Bendix 8101 Oxides of Nitrogen Analyzers and Palmes passive monitors. In-home stationary Palmes tubes are very accurate compared to chemiluminescent monitors (R2 =0.97). Chemiluminescent monitors and Palmes tubes worn by subjects do not give the same measurement of of personal NO2 exposure (R2 =0.83), presumably because it is not possible for a stationary monitor to estimate personal exposure as well as Palmes tubes do. Mean winter NO2 levels in homes with kerosene space heaters varied widely (71.4 ±73.2 ppb), but were more than 2 times the levels found in homes with gas stoves (26.5 ±14.2 ppb) and ten times the levels of homes without combustion sources (4.6 ±3.2 ppb). Clinical, epidemiological, and toxicological evidence suggest that peak short-term levels are more important than long-term averages in determining human health effects. Continuous monitoring data indicate that combustion appliances caused peak NO2 levels of 100 ppb or more during 9 of the 40 monitoring-weeks in this study. Regression analysis suggests that peak values contributed more significantly to a mother's net exposure than to her child's (P < 0.05). In conclusion Palmes tubes provide an accurate and convenient measure of net personal exposure to NO2. Average exposure, however, is not the best indicator of indoor NO2 levels which may have significant health impacts. Increased venting and improved combustion appliance technology provides the most feasible alternative for lowering in-home exposure to NO2.Master of Science in Public Healt