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Air Quality Impacts of Land-Atmosphere Interactions

Project: Non-funded ProjectResearch


Poor air quality is responsible for 4 million deaths around the world every year. In Europe alone, more than 250,000 people die annually due to inhaling harmful air pollutants, including ozone (referred to as ground-level ozone to distinguish it from the beneficial stratospheric ozone layer) and aerosol particles (termed particulate matter or PM in this context). In the UK, the air quality routinely encountered in our cities is a major hazard to health and a matter of increasing public concern. Air pollution also affects vegetation; stunting growth, jeopardising yields of major food crops and limiting the absorption of CO2 by trees.
What causes air pollution, and why is it not responding to our efforts to improve the situation? Although some air pollutants are directly emitted into the atmosphere, most are ‘secondary’ pollutants, formed as the end result of a complex series of reactions between ‘primary’ (precursor) compounds. These precursors come from many sources, both anthropogenic and natural, have different reactivity and different lifetimes in the atmosphere, making it hard to predict where, when and how they will combine.
My research focuses on the natural, or ‘biogenic’, precursors of ozone and PM. Every year, over one thousand million tonnes of biogenic compounds, are released from vegetation (mainly the world’s forests). That’s more than the combined mass of every man, woman and child on the planet. Many biogenics are highly reactive, and in the presence of the nitrogen oxides (NOx), a product of combustion, rapidly oxidise forming ozone and ‘secondary organic aerosol’. Measurements from around the world show the latter to be a major component of the most harmful PM (PM2.5 and smaller), even in urban areas with little vegetation.
How are emissions of these biogenics affected by the myriad interacting physical and chemical processes that occur in the space between the ground and the top of the vegetation? What reactions are the precursors involved in, and what products are formed? How and to where are they transported? How does poor air quality affect vegetation and hence the emissions? How does it affect our health and well-being? How can we compare these direct impacts with the benefits of green spaces?
My work will provide answers to these questions. I develop and apply computer models of the processes involved in the emission, transformation and transport of biogenic compounds, the most ubiquitous precursors of secondary air pollutants. I use both a highly detailed model describing the release of biogenics into the atmosphere at a single location, and a model of atmospheric chemical reactions that simulates the formation of air pollution over a region. While the current computer models do not take a holistic approach I will combine my models, seamlessly integrating the land and atmosphere.
But my research won’t end there. I apply statistical relationships to deduce the impact that poor air quality has on our health and on the productivity of vegetation, particularly on key agricultural crops. Furthermore, I close the circle by accounting for the effect of this damage on the emissions and chemistry of the precursors and hence future air quality. I will create a new air quality index that accounts for the impacts of air pollution on all aspects of our lives, assisting policymakers.
Only once we fully understand the causes and implications of poor air quality can we find solutions, enabling us all to breathe freely in the future.


AQuILA is the overarching theme of my Royal Society Dorothy Hodgkin Research Fellowship