The collection of PM10 for toxicological investigation: comparisons between different collecting devices

A positive correlation has been established between increased levels of airborne particulate pollution and adverse health effects, the toxicological mechanisms of which are poorly understood. For toxicologists to unambiguously determine these mechanisms, truly representative samples of ambient PM10 are required. This presents problems, as PM10 collecting equipment commonly employed, such as the Tapered Element Oscillating Microbalance (TEOM), heat the inflow to exclude moisture or use fibrous filters, resulting in a PM10 sample that may have undergone significant chemical change on the filter surface or is contaminated by filter fibres. Other systems (i.e. Negretti and Partisol) can successfully collect PM10 without chemical alteration or filter contamination. Comparative collections from Port Talbot, S. Wales suggest that TEOMs and Negretti/Partisol systems collect different PM10's; the principle difference arising from the TEOM's heating chamber, which precipitates water-soluble ions and volatilises some organic components. This results in both the mass and composition of the PM10's being altered. Particle size distributions for Negretti and Partisol collections highlighted differences mainly attributed to different flow rates. The results of this work demonstrate that simple correlations between PM10 mass and adverse health effects are problematic. Furthermore, elucidation of the complex fractionation and chemical changes in different collectors is necessary.