In 2002 I presented to the delegates at an international conference on Urban Air Pollution, Bioindication and Environmental Awareness at the University of Hohenheim, images from an exhibition on pollution and plants that I planned at the Fruitmarket Gallery, Edinburgh, which showed the impact of traffic on plants in Princes Street Gardens, Edinburgh. The plant petals were examined by an advanced electron microscope at the Department of Geology, Edinburgh University. This equipment enabled the viewing of fine diesel particles, located on the plant petals, which are an unseen danger behind major health problems.

The idea of the exhibition was to focus on the beauty of plants that we enjoy, oblivious to the danger that exists around us – smelling the plant, while unaware that we are breathing in the pollution particles. Princes Street Gardens is a dramatically situated park, enjoyed by thousands of people each year, in a depression in the land between Edinburgh Castle on its crag, and the busy thoroughfare of Princes Street, [then, in 2002] full of diesel-powered buses throughout the day. At that time most European governments were in denial about the impact of air quality on human health and the significant risks to life.

In the intervening years the concerns around air quality have gained international prominence. ‘Green’ buses in Edinburgh and other cities are far less polluting than in the past. But World Health Organisation evidence – widely publicised in order to inform policy-making – shows that air pollution at current levels in most European cities is responsible for a significant burden of deaths, hospital admissions and exacerbation of symptoms, particularly in the area of cardio-respiratory disease.

The air we breathe contains emissions from motor vehicles, industry, heating and commercial sources, as well as household fuels. Air pollution harms human health, particularly in those already vulnerable because of their age or existing health problems. Exposure to air pollutants is largely beyond individuals’ control and requires action by public authorities at all levels. Ozone pollution causes breathing difficulties, lung and heart diseases, triggers asthma symptoms, and is associated with about 21,000 premature deaths per year in the European region.