Urban trees in London emit large quantities of chemicals that react in the atmosphere to form air pollutants hazardous to our health. These emissions can be particularly large during heatwaves that are becoming more common and severe. Many of the tree species in London are large emitters. The way we represent emissions from these urban trees in air quality models is problematic, so we have a very poor understanding of how the choice of trees for urban greening projects influence air quality. Here the student will collect and use data on tree species and characteristics in London to model the emissions from trees, to determine how these respond to environmental factors like meteorology and heatwaves, what the contribution is of trees to urban air pollution, and the impact this has on population health in London. This will then provide the groundwork to explore the effects of trees on air pollution in other cities in the UK and elsewhere in the world.