The NERC URGENT thematic programme was set up to integrate urban environmental research across the geological, ecological, freshwater and atmospheric sciences. It worked in partnership with city authorities, industry and regulatory bodies.

The URGENT "Air" data were mainly in situ ground based measurements in urban and suburban areas but also include observations from aircraft, lab measurements and model results. Retrieved variables include atmospheric chemical species and aerosols, photolysis rates and meteorological/radiative parameters.

The thematic programme began in 1998 and lasted for 7 years.

Tracer and Dispersion of Gaseous Pollutants (GASPOL) was a NERC Urban Regeneration and the Environment (URGENT) Air project (GST/02/1974 - Duration: 2/9/1998 - 31/8/2001) led by Prof Peter Simmonds, University of Bristol.

The transport and dispersion of pollutants, within and from a large urban area, are important processes due to their potential environmental impact on city inhabitants and those living in nearby communities. The release of atmospheric Tracers is a powerful technique to simulate the dispersion of pollutants and to enable direct measurement of the transport path and concentrations along the trajectory. Successful Tracers a inert, non-toxic, non-depositing, with low atmospheric background concentrations, long atmospheric lifetimes, and limited commercial use. This research project developed the Tracer technology necessary to characterise atmospheric dispersion within the urban environment.

Bristol University were exploiting the many years of experience in Tracer technology coupled with recent advances in gas chromatography/mass spectrometry techniques. There were several components to developing an effective experimental Tracer technology and this project was addressing each of these in turn:

-Selection of Tracers
-Analytical instrumentation for their quantitative determination in the femtolitre/litre range
-Design and construction of automated sequential samplers
-Tracer release apparatus
-The preparation of accurate perfluorocarbon standards.