Social impacts of pollutants from mobile sources are a key element in urban design and traffic planning. One of the most relevant impacts is health effects associated with high pollution periods. Madrid is a city that suffers chronic congestion levels and some periods of very stable atmospheric conditions; as a result, pollution levels exceed air quality standards for certain pollutants. This paper focuses on the social evaluation of transport-related emissions. A new methodology to evaluate those impacts in monetary terms has been designed and applied to Madrid. The method takes into account costs associated with losses in working time, mortality and human suffering; calculated using an impact pathway approach linked to CORINAIR emissions. This also allows the calculation of social costs associated with greenhouse gas impacts. As costs have been calculated individually by effect and mode of transport, they can be used to design pricing policies based on real social costs. This paper concludes that the health and social costs of transport-related air pollution in Madrid is 357 Meuro. In these circumstances, the recent public health tax applied in Madrid is clearly correct and sensible with a fair pricing policy on car use.