Simon Birkett is founder and director of Clean Air in London, which has a mission to achieve full compliance with World Health Organisation guidelines for air quality throughout London and elsewhere. Between 2015 and 2019, Simon was the air pollution stakeholder on the High Level Intergovernmental Stakeholder and Advisory Group for UNEP's sixth global environment outlook (GEO6). He champions a 'One Air' approach, which advocates fighting climate change and air pollution together.