To assess the impact of particulate emissions from Port Talbot Works on local air quality, a detailed mathematical analysis of ambientparticulate data collected in the borough over several years has been completed, with a special focus on the period following the stoppage ofn° 5 Blast Furnace in 2001. This work was done following the declaration of an Air Quality Management Area (AQMA) adjacent to PortTalbot Works, in order to tackle the high incidence of exceedances of the 24 h PM10 objective in this area.