Outdoor air pollution is a crucial and arduous issue in Asia.Many governments including Hong Kong have established air quality monitoring network and provides hourly reported Air Quality Index (AQI) and Air Quality Health Index (AQHI).However,the public can only understand the current condition of air quality but is unable to discern the long-term risks.The study aims to assess the health risks from ambient air pollution according to different classes patial distribution and living habit by a spatial multi-agent simulation (SMAS).The developed SMAS model can classify the possible added risks for different groups of residents living in Hong Kong by linking air quality monitoring informa-tion to population activity.The results show that the health risks of children and the eld-erly are about 5% higher than youths and adults.Regional differences demonstrated the health risks of residents living in Wan Chai and eastern districts are relatively higher than the others.The developed model is expected to be a powerful tool to provide comprehen-sive health risk information to the Hong Kong residents.