Inspired by the simplicity of how nature solves its problems, we develop a flocking controller that would enable the localisation and subsequent mapping of environmental pollutants. Pollutants could range from chemical leaks to invisible air borne harzardous materials. We use simulation results to validate our approach and then briefly discuss how to implement the controller onto a real robotic platform. Our motivation is to use the advantages offered by swarm robotics- simple, multiple and cheap agents- to achieve a collective complex single goal of mapping an environmental pollutant spread over a large area. We aim to make our approach as simple as possible yet highly effective in generating the map.