Diesel particle composition after exhaust after-treatment of an off-road diesel engine and modeling of deposition into the human lung Kati Oravisjärvi a,n , Mari Pietikäinen a , Juhani Ruuskanen b , Seppo Niemi c,d , Mika Laurén d , Arto Voutilainen e,f , Riitta L Keiski a , Arja Rautio g a Department of Process and Environmental Engineering, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland b Department of Environmental Science, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland c Department of Electrical Engineering and Energy Technology, University of Vaasa, P.O. Box 700, FI-65101 Vaasa, Finland d Turku University of Applied Sciences, Joukahaisenkatu 3A, FI-20520 Turku, Finland e Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland f Rocsole Ltd., FI-70211 Kuopio, Finland g Centre for Arctic Medicine, Thule Institute, University of Oulu, P.O. Box 7300, FI-90014 Oulu, Finland article info Article history: Received 17 July 2013 Received in revised form 20 November 2013 Accepted 29 November 2013 Available online 16 December 2013 Keywords: Nanoparticles PAH DPF SCR Human lung deposition model Diesel particles abstract Regional deposition of diesel particles in the human lungs was analyzed and the chemical composition of inhaled particles was investigated. The off-road diesel engine with a diesel particulate filter (DPF) or a selective catalytic reduction (SCR) unit and without any exhaust after-treatment system was used. Around 85–95% of the measured particles were of ultrafine size and 53–84% of those nanoparticles. Over 70% of the deposited particles under 0.1 mm and about 45–70% of the deposited particles from 0.1 to 1 mm reach also the alveolar–interstitial level. Elements analyzed in particles were C, O, Fe, Si, Ti, Na, K, Ca, Mg, Ba, Mn, Zn, Cu, Cl, P, S and N. The proportion of PAHs in the measured particle mass was 0.05% and carcinogenic ones represented 1.3% of the total PAHs. The DPF system removed particles efficiently and up to 99% of the particles were removed. The total number of particles deposited in the lungs was generally lower when DPF was used compared to other setups. These particles contained though the largest variety of elements, which are commonly considered harmful to humans. Therefore it is difficult to conclude, whether exhaust particles from a diesel engine with a DPF unit would be less harmful to human health. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Air pollution is a major health risk causing cancer and several other health impacts (IARC, 2013a). The particles emitted from off-road engines may be harmful for workers. Epidemiological evidence suggests that a long-term employment in jobs with a substantial diesel exhaust exposure is associated with a 20–50% increase in the risk of lung cancer (Zelikoff, 2000) and there is a need for occupational exposure regulations (Maricq, 2007). In June 2012, the International Agency for Research on Cancer (IARC) classified diesel engine exhaust as carcinogenic to humans (group 1) (IARC, 2013a, 2013b). Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jaerosci Journal of Aerosol Science 0021-8502/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jaerosci.2013.11.008 n Corresponding author. Tel.: þ358 50 543 7323; fax: þ358 2 9448 2304. E-mail address: kati.oravisjarvi@oulu.fi (K. Oravisjärvi). Journal of Aerosol Science 69 (2014) 32–47