This volume presents a collection of fully peer-reviewed papers on the latest advances in the field of urban air quality. These papers were presented at the Third International Conference on Urban Air Quality - Measurement, Modelling and Management, held in Loutraki, Greece, March 19-23, 2001. The conference provided a platform for 175 scientists from over 30 different countries to exchange, discuss and advance the latest research findings in this field. Papers were presented on topics including air quality management and policy, emissions, measurements of air pollution, local and urban scale modelling, aerosols, urban meteorology, remote sensing and exposure.
This work will prove useful to universities, environmental research organisations, research students, undergraduate students, environmental consultants, industrial organisations, and local (city) authorities.

Since the first international conference on urban air quality, held at the University ofHertfordshire in 1996, significant advances have taken place in the field of urban air pollution. In addition to the scientific advances in the measurement, modelling and management of urban air quality, significant progress has been achieved in relation to the establishment of major frameworks to ensure a more effective mechanism for international collaboration. Two such frameworks are SATURN (Studying Atmospheric Pollution in Urban Areas) and TRAPOS (Optimisation of Modelling Methods for Traffic Pollution in Streets). In response to such advances, the second international conference was held at the Technical University of Madrid in March 1999 with active participation of SATURN and TRAPOS investigators. The organisation of the conference was headed by the Institute of Physics in collaboration with the Technical University of Madrid and the University of Hertfordshire. The support of IUAPPA and AWMA ensured a truly worldwide promotion and participation. The meeting attracted 140 scientists from 26 different countries establishing it as a major forum for exchanging and discussing the latest research fmdings in this field.

The increasing concern over environmental and health impact of urban air pollution has lead to a growing need for an international conference focussing specifically on urbanised regions. Although, air quality has gained importance through out the world, it is especially in areas of high urban development that the problems are particularly acute. Scientific interest in this field is particularly evident from the growing number of journal publications and conference presentations. The numerous conferences held every year on air pollution, however, have tended to encompass a broad theme and have not specifically focussed on the urban environment. In order to address this need an international conference on urban air quality was organised by the Environmental Physics Group of the Institute of Physics in collaboration with the Royal Society of Chemistry (RSC), The Royal Meteorological Society (RMS) and the National Society for Clean Air and Environmental Protection (NSCA). Over 100 participants from various countries attended this first international conference on urban air quality. The aim of the conference was to provide a forum for open scientific discussion on the latest advances in the field of urban air quality monitoring and modelling. The range of topics included: chemical and biogenic pollutants, monitoring techniques, instrumentation, analysis of pollutants, spatial and temporal interpretation of air quality data, emission sources and modelling of air quality. All papers submitted for publication were peer reviewed and consequently, some articles were not successful in the refereeing process and have not been included in this special issue.

Air pollution affects us all in a number of crucial ways, causing lasting damage to our health and our environment. Whereas primary pollution can result from local activities, the extent of the impact can be felt at spatial scales from the individual up to the whole planet, and temporal scales from minutes to decades. Consequently, pollution of our atmosphere remains a critical concern, warranting continued scientific investigation and the development of effective local and global solutions. 'The World Atlas of Atmospheric Pollution' clearly and engagingly summarises current understanding of the state of air pollution on city to global scales.

Using high-quality graphical illustrations, the Atlas begins with a historical perspective before addressing topics such as urban and global air pollution, long-range transmission of pollution, ozone depletion and the impacts of air pollution, as well as future trends. Each chapter provides an introduction to the topic and graphical representations of the spatial and temporal distributions of air pollutants. Wherever possible, the chapters give a world-wide view of the state of our atmosphere. The illustrations are supported by explanations and other background material, allowing the reader to gain an informed insight into emission sources, the resulting atmospheric concentrations of key pollutants and their associated impacts.

Pollution of our atmosphere affects every aspect of our environment, at every scale. This atlas describes the distribution of pollution from local to global spatial scales, the historical and future trends of the major pollutants, the impacts of atmospheric pollution on the environment, and much more.

Since the first international conference on urban air quality, held at the University ofHertfordshire in 1996, significant advances have taken place in the field of urban air pollution. In addition to the scientific advances in the measurement, modelling and management of urban air quality, significant progress has been achieved in relation to the establishment of major frameworks to ensure a more effective mechanism for international collaboration. Two such frameworks are SATURN (Studying Atmospheric Pollution in Urban Areas) and TRAPOS (Optimisation of Modelling Methods for Traffic Pollution in Streets). In response to such advances, the second international conference was held at the Technical University of Madrid in March 1999 with active participation of SATURN and TRAPOS investigators. The organisation of the conference was headed by the Institute of Physics in collaboration with the Technical University of Madrid and the University of Hertfordshire. The support of IUAPPA and AWMA ensured a truly worldwide promotion and participation. The meeting attracted 140 scientists from 26 different countries establishing it as a major forum for exchanging and discussing the latest research fmdings in this field.

Funding Science: An Immense Challenge The real challenge in science should be hypothesis formation, experimental design and conducting the actual research under rigorous control and experimental condi of tions with the best available equipment/infrastructure. However, in many parts the world, the real challenge in science is trying to obtain some minimal amount of funding to initiate research. Every country in the world is challenged with an im mense number of interconnected environmental and health problems. Examples in clude biologically and chemically contaminated water and soil, air pollution, waste and sewage treatment, a multitude of infectious diseases in humans, animals and plants, global change, population growth, alternate energy sources, deforestation, floods, crop production and so on. Solutions to these national and international problems require training and re search to ensure the best available people and knowledge are available to man age and/or solve these problems. This can only be accomplished if the research community has the funding to conduct priority research and apply the knowledge globally. The challenge in science should be discovering the unknown and col laborative research/training of new scientists. Too often the challenge is how to conduct research without proper support. Many scientists are likely of the opinion that it is not their jobs/careers that is stressful, but the inability to do their research properly, that is stressful. Good research in a knowledge based economy requires proper funding.

The increasing concern over environmental and health impact of urban air pollution has lead to a growing need for an international conference focussing specifically on urbanised regions. Although, air quality has gained importance through out the world, it is especially in areas of high urban development that the problems are particularly acute. Scientific interest in this field is particularly evident from the growing number of journal publications and conference presentations. The numerous conferences held every year on air pollution, however, have tended to encompass a broad theme and have not specifically focussed on the urban environment. In order to address this need an international conference on urban air quality was organised by the Environmental Physics Group of the Institute of Physics in collaboration with the Royal Society of Chemistry (RSC), The Royal Meteorological Society (RMS) and the National Society for Clean Air and Environmental Protection (NSCA). Over 100 participants from various countries attended this first international conference on urban air quality. The aim of the conference was to provide a forum for open scientific discussion on the latest advances in the field of urban air quality monitoring and modelling. The range of topics included: chemical and biogenic pollutants, monitoring techniques, instrumentation, analysis of pollutants, spatial and temporal interpretation of air quality data, emission sources and modelling of air quality. All papers submitted for publication were peer reviewed and consequently, some articles were not successful in the refereeing process and have not been included in this special issue.