Automated Mineralogical Analysis of PM10: New Parameters for Assessing PM Toxicity

This work provides the first automated mineralogical/phase assessment of urban airborne PM, c, and a new method for determining particle surface mineralogy (PSM), which is a major control on PM toxicity in the lung. PM10 was analyzed on a TEOM filter (Aug.-Sept. 2006 collection) from the London Air Quality Network Bexley, East London, U.K. A cross-section of the filter was analyzed using a QEMSCAN automated mineralogical,analysis system which provided 381 981 points of analysis for 14 525 particles over a period of 9 h 54 min. The method had a detection limit for individual mineral components of 0.05 ppm (by area). Particle shape and mineralogical characteristics were determined for particles in the size ranges PM10-4, PM4-2.5, and PM2.5-0.08 fraction contained 2 orders of magnitude moe miernal particles than the PM10-4 and PM4-2.5 fractions, however the PM10-4 fraction forms 94% and 79% of the mineral mass and surface area, respectively. PSM of the PM10 was dominated by gypsum (36%), plagioclase (16%), Na sulphates (8%), and Fe-S-O phases (8%) in the PM10-2.5, which may be important in explaining the toxicity of the coare fraction. The wider implications of the study are discussed.