Systems and methods for gas detection within vehicles are disclosed herein. An example method includes monitoring background gas concentrations in a vehicle using a robot having a gas module having a non-selective sensor and a selective sensor, determining a concern index based on output of the gas module, determining when the concern index exceeds a threshold which indicates presence of a non-atmospheric gas, causing the robot to traverse an operating area when the concern index exceeds the threshold to search for a source of the non-atmospheric gas by measuring gas concentration gradients, classifying the non-atmospheric gas using the selective sensor of the gas module and identifying a location of the source of the non-atmospheric gas in the vehicle based on the gas concentration gradients.