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153195 
Journal Article 
First gaseous sulfuric acid measurements in automobile exhaust: Implications for volatile nanoparticle formation 
Arnold, F; Pirjola, L; Aufmhoff, H; Schuck, T; Lahde, T; Hameri, K 
2006 
1 
Atmospheric Environment
ISSN: 1352-2310
EISSN: 1873-2844 
40 
37 
7097-7105 
WOS:000241636000001 
Gaseous sulfuric acid (GSA) is thought to represent an important if not the most important nucleating gas present in modern diesel automobile exhaust. It triggers the formation of new aerosol particles, which grow by condensation and coagulation. Here we report on the first measurements of GSA in automobile exhaust. The experiment was made using a modern passenger diesel car equipped with an exhaust after-treatment system composed of an oxidation catalyst and a diesel-particle filter. The diesel fuel used had an ultra-low sulfur mass fraction of only 5 x 10(-6). Measured GSA number concentrations reached up to I X 109 cm(-3). Freshly nucleated particles with diameters larger than 3 nm were also measured. The concentrations reached up to 1 x 10(5) cm(-3) and were positively correlated with GSA for GSA exceeding a threshold value in the range of 5 x 10(7)-2 X 10(8) cm(-3). This suggests that GSA was involved in the formation of new volatile particles. (c) 2006 Elsevier Ltd. All rights reserved. 
sulfuric acid measurements; diesel nanoparticles; conversion factor; after-treatment system