Atmospheric pollution affects 9 out of 10 city dwellers, and kills 7 million people a year. With an epidemic of cancers among adults and widespread asthma among children, China and India are on a constant health alert. The rest of the world is not free from harm as the pollutants are travelling. Even European and North American cities exceed World Health Organization guidelines. Faced with this growing public health concern, how can people protect themselves? Featuring scientists and political leaders from Sao Paulo, New Delhi, Mexico, Paris, Beijing and Berlin, this documentary investigates the dangers of toxic emissions and looks at measures being taken to reduce air pollution from urban transport systems and industries.