Relationships between size segregated mass concentration data and ultrafine particle number concentrations in urban areas

Mass concentration data derived from samples collected with a micro-orifice uniform deposit impactor (MOUDI) in six Australian urban centers during pe riods of significant particle loading have been used to investigate the rel ationships between TSP, PM10, PM2.5, PM1 and ultrafine particles. While PM1 0 and PM2.5 display a clear relationship, the lack of correlation between P M10 and the coarse fraction of PM10 (PM10-PM2.5) suggests that variation in PM10 is dominated by variance in PM2.5. Given that particles of less than 2.5 mu m are suspected to have adverse health effects, increasing the exten t of PM2.5 monitoring may improve detection of relationships between air po llution and human health. A lack of correlation between both PM10 and PM2.5 with ultrafine mass concentrations indicates that PM10 and PM2.5 cannot be used as a surrogate for ultrafine mass concentration. Similarly, ultrafine number concentrations cannot be inferred from mass concentration informati on determined by the MOUDI. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.