Background: The World Health Organization (WHO) stresses the need to create active environments, able to promote physical activity of people, according to their ability. Objective; This paper describes a new tool curried out to meaasure the relationship between the characteristics of urban space and its salutogenicity, intended as its ability to address population toward healthy lifestyles. Salutogenity has been read in terms of ergonomics of urban space. Method: The tool includes a set of 67 parameters, classified in needs, requirements and performance. It focuses on three requirements: usability, wellbeing and safety. The related performances are measured by a set of 29 indicators, divided in 5 categories (natural elements, built environment, mobility, urban furniture and perceived environment). To calibrate the tool, it was applied to 10 neighborhoods of Rieti city. To take into account the relationship between the variables, a causal network (Bayesian network) was applied. Findings: The average value of ergonomics of Rieti city, obtained applying the discrete bayesian model is 44.25%. Using the network, it is evident that by intervening on one node, the information requested expands to all the other nodes to which it is connected directly or indirectly, showing all the possible related factors. Conclusions: By using the tool and the discrete bayesian network it was possible to focus on the realities requiring analysis and to indicate the areas where the first interventions would be useful to increase the value of the analyzed nodes and, consequently, to improve the urban salutogenicity.