Monitoring urban air quality with a diffusion charger based electrical particle sensor A. Järvinen a , H. Kuuluvainen a , J.V. Niemi b,c , S. Saari a , M. Dal Maso a , L. Pirjola d , R. Hillamo e , K. Janka f , J. Keskinen a , T. Rönkkö a,⇑ a Aerosol Physics Laboratory, Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland b Helsinki Region Environmental Services Authority (HSY), P.O. Box 100, FI-00066 HSY, Finland c Department of Environmental Sciences, University of Helsinki, P.O. Box 65, FI-00014 University of Helsinki, Finland d Department of Technology, Metropolia University of Applied Sciences, Kalevankatu 43, FI-00180 Helsinki, Finland e Air Quality, Finnish Meteorological Institute, Erik Palménin aukio 1, FI-00560 Helsinki, Finland f Pegasor Oy, Hatanpäänvaltatie 34 C, FIN-33100 Tampere, Finland article info Article history: Received 28 February 2014 Revised 12 September 2014 Accepted 1 October 2014 Available online xxxx Keywords: Particle sensor Urban air quality Traffic emissions Instrument comparison abstract Urban air contains considerable amounts of harmful gaseous substances and aerosol particles. In this study, a recently intro- duced diffusion charger based PPS-M particle sensor (Pegasor Oy, Tampere, Finland) was evaluated for outdoor air quality measure- ments in urban environment. The PPS-M particle sensor was used in two stationary air quality measurement stations, one located in the roadside environment and the other in residential area, and in a mobile laboratory. The sampling of urban aerosol to the PPS-M sensor was performed without any pre-conditioning of aerosol. The sensor response to PM 2.5 varied between the measurements, being between 7 and 30 fA/(lg/m 3 ) depending on the aerosol source. The highest PM 2.5 response was observed in the roadside study for exhaust particles while the lowest PM 2.5 response was observed for large long range transported aerosol particles having relatively large mean particle size. The sensor signal was found to produce very linear response, with only minimal deviation, to the lung deposited particle surface area concentration (from 4.5 to 6 fA/(lm 2 /cm 3 )) and to the condensation sink of urban air particles (from 1.0  10 4 to 1.2  10 4 fA cm 3 ). The sensor response to parti- cle number concentration was defined to be 0.0044 fA/(1/cm 3 ) in roadside environment. In this environment, the signal was found to correlate also with NO and NO 2 concentrations of roadside air http://dx.doi.org/10.1016/j.uclim.2014.10.002 2212-0955/Ó 2014 Published by Elsevier B.V. ⇑ Corresponding author. Tel.: +358 40 198 1019. E-mail address: topi.ronkko@tut.fi (T. Rönkkö). Urban Climate xxx (2014) xxx–xxx Contents lists available at ScienceDirect Urban Climate journal homepage: www.elsevier.com/locate/uclim Please cite this article in press as: Järvinen, A., et al. Monitoring urban air quality with a diffusion charger based electrical particle sensor. Urban Climate (2014), http://dx.doi.org/10.1016/j.uclim.2014.10.002