This paper estimates the economic benefits from reduced asthma problems among pre-school children caused by the Stockholm congestion charging (SCC) scheme. From previous epidemiological studies, it has been found that there is a positive correlation between reduced emissions from car and improvement of asthma prevalence. The paper focuses on densely populated inner-city Stockholm where people, especially children, are supposed to be highly exposed to air-borne pollution. Since traffic emissions has been reduced significantly in inner-city Stockholm as a result of introducing SCC scheme, and nitrogen-dioxide (NO2) is one of the influential determinants of childhood asthma, the economic benefits have been calculated due to reduction in NO2 concentration. In addition, both the direct and indirect approaches are followed to estimate health benefits. Under the direct approach, reduced costs of hospitalization for asthma is calculated, while reduced costs of parent's sick leave for child's asthma is considered under indirect one. Finally, total health gains are figured out from two kinds of benefits.