Aims : The aims of this session are to provide up-to-date state-of-the-art summaries of the evidence linking ambient air exposure and dietary exposures to childhood asthma; some of the underlying mechanisms will also be reviewed. The evidence linking accelerated growth and childhood obesity to childhood asthma will be summarised, and an overview of developmental programming will be provided. Finally, how environmental factors could influence the development of asthma via epigenetic mechanisms will be described.