The PM2.5 and PM10 particles in urban areas of Taiwan

This study conducted an atmospheric aerosol sampling to measure the PM10 (p articles < 10 mu m in aerodynamic diameter) and PM2.5 (particles < 2.5 mu m in aerodynamic diameter) mass concentrations from October 1996 to June 199 7 in northern (Taipei), central (Taichung) and southern (Kaohsiung), the th ree largest cities of Taiwan. Seventy-eight samples were obtained to measur e the mass concentrations of PM10 and PM2.5 from nine sampling sites. Accor ding to those results, the PM10 mass concentrations in Taipei, Taichung and Kaohsiung were 42.19, 60.99 and 77.10 mu g/m(3), respectively. The corresp onding PM2.5 mass concentrations were 23.09, 39.97 and 48.47 mu g/m(3), res pectively. The PM2.5 fraction accounted for 61-67% of the PM10 mass in cent ral and southern Taiwan, but was lower (54-59%) in northern Taiwan. Some sa mples in which the PM2.5 fraction was overwhelmingly dominant could reach a s high as 80-95% of the PM10 mass. In addition, the PM2.5, PM10 levels and PM2.5/PM10-2.5 (particles with aerodynamic diameters ranging from 2.5 to 10 mu m) ratios in metropolitan Taiwan significantly fluctuated from site-to- site and over time. Moreover, ambient daily PM2.5 and PM10-2.5 mass concent rations did not correlate well with each other at most of the sampling site s, indicated that they originated from different kinds of sources and emitt ed variedly over time. (C) 1999 Published by Elsevier Science B.V. All righ ts reserved.