The invention provides a method for determining a transportation direction (TD) for a user, the method comprising: receiving a current location (CL) of the user； receiving a pollution based input value (PIV) related to air pollution in a geographical area (GA) including the current location (CL)； determining the transportation direction (TD) using the pollution based input value such that the user is subjected to a lowest level of pollution and/or such that a predefined maximum level of pollution to which the user is subjected is not exceeded； and retrieving a human activity based input value, wherein the human activity based input value is based on activity data from a portable device (100) configured to sense an activity level of the human wearing the portable device (100)； and updating the transportation direction (TD) using the human activity based input value (HAIV).
