Modelling the long-range transport of secondary PM10 to the UK

The fine fraction of airborne particulate matter (PM10) is known to be harmful to human health. In order to establish how current air quality standards can best be met now and in the future, it is necessary to understand the cause of PM10 episodes. The UK Met Officeʹs dispersion model, NAME, has been used to model hourly concentrations of sulphate aerosol for 1996 at a number of UK locations. The model output has been compared with measured values of PM10 or sulphate aerosol at these sites and used to provide attribution information. In particular two large PM10 episodes in March and July 1996 have been studied. The March episode has been shown to be the result of imported pollution from outside the UK, whereas the July case was dominated by UK emissions. This work highlights the need to consider trans-boundary pollution when setting air quality standards and when making policy decisions on emissions.