Research

Physicochemical characterisation of combustion particles from vehicle exhaust and residential wood smoke

Anette Kocbach¹ , Yanjun Li² , Karl E Yttri³ , Flemming R Cassee⁴ , Per E Schwarze¹ and Ellen Namork¹

¹  Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404, N-0403 Oslo, Norway

²  Department of Physics, University of Oslo, Norway

³  Department for Chemical Analysis, Norwegian Institute for Air Research, Kjeller, Norway

⁴  Center of Environmental Health Research, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands

author email corresponding author email

Particle and Fibre Toxicology 2006, 3:1doi:10.1186/1743-8977-3-1

Published:	3 January 2006

Abstract

Background

Exposure to ambient particulate matter has been associated with a number of adverse health effects. Particle characteristics such as size, surface area and chemistry seem to influence the negative effects of particles. In this study, combustion particles from vehicle exhaust and wood smoke, currently used in biological experiments, were analysed with respect to microstructure and chemistry.

Methods

Vehicle exhaust particles were collected in a road tunnel during two seasons, with and without use of studded tires, whereas wood smoke was collected from a stove with single-stage combustion. Additionally, a reference diesel sample (SRM 2975) was analysed. The samples were characterised using transmission electron microscopy techniques (TEM/HRTEM, EELS and SAED). Furthermore, the elemental and organic carbon fractions were quantified using thermal optical transmission analysis and the content of selected PAHs was determined by gas chromatography-mass spectrometry.

Results

Carbon aggregates, consisting of tens to thousands of spherical primary particles, were the only combustion particles identified in all samples using TEM. The tunnel samples also contained mineral particles originating from road abrasion. The geometric diameters of primary carbon particles from vehicle exhaust were found to be significantly smaller (24 ± 6 nm) than for wood smoke (31 ± 7 nm). Furthermore, HRTEM showed that primary particles from both sources exhibited a turbostratic microstructure, consisting of concentric carbon layers surrounding several nuclei in vehicle exhaust or a single nucleus in wood smoke. However, no differences were detected in the graphitic character of primary particles from the two sources using SAED and EELS. The total PAH content was higher for combustion particles from wood smoke as compared to vehicle exhaust, whereas no source difference was found for the ratio of organic to total carbon.

Conclusion

Combustion particles from vehicle exhaust and residential wood smoke differ in primary particle diameter, microstructure, and PAH content. Furthermore, the analysed samples seem suitable for assessing the influence of physicochemical characteristics of particles on biological responses.