Particle number, particle mass and NOx emission factors at a highway and an urban street in Copenhagen 1Institute of Nuclear and New Energy Technology, Tsinghua University, 100084, Beijing, China
2Department of Atmospheric Environment, National Environmental Research Institute, Aarhus University, 4000 Roskilde, Denmark
Received: 10 July 2009 – Published in Atmos. Chem. Phys. Discuss.: 18 September 2009 Abstract. This paper presents measurements of traffic-generated gas and particle
pollution at two sites, one near a major highway and one near a busy urban
street in Copenhagen, Denmark. Both sites were equipped for a 4-week period
with a set of two measurement stations, one close to the kerbside and one
background station. Measurements were carried out from March to April~2008,
investigating NOx concentrations, submicrometer particle number size
distribution (size range 10–700 nm), particle mass (PM2.5, PM10),
and meteorological parameters. In this study we also estimate the emission
factors for NOx, particle number and particle mass using measured
traffic volume and dilution rate calculated by the Operational Street
Pollution Model (WinOSPM).
Revised: 03 March 2010 – Accepted: 08 March 2010 – Published: 24 March 2010
The mean concentrations of most of the measured pollutants are similar for
the highway and the urban kerbside stations due to similar traffic density.
The average concentrations of NOx are 142 μg m−3 and
136 μg m−3 for the highway and the urban kerbside stations, respectively.
These values are about 5 times higher compared to the corresponding
background values. The average particle number concentration is 24 900 particles cm−3 and 27 100 particles cm−3 for the highway and the
urban kerbside stations, respectively, and these values exceed those
measured at the background stations by a factor of 3 to 5.
The temporal variation of the traffic contribution (difference of kerbside
and background concentrations) is analysed for NOx, particle number and
mass, and it follows the traffic pattern at the urban and the highway sites.
Emission factors for particle number are found to be quite similar at both
sites, (215±5) 1012 particles veh−1 km−1 for the highway
and (187±3) 1012 particles veh−1 km−1 for the urban
site. Heavy duty vehicles (HDVs) are found to emit about 20 times more
particles than light duty vehicles (LDVs), which is in good agreement with
other published studies. Emission factors are also determined for individual
particle modes identified in the size spectra. Average fleet emission
factors for PM2.5 at the highway and the urban site are 29 mg veh−1 km−1 and 46 mg veh−1 km−1, respectively. The estimated
particle number and size spectra emission factors will provide valuable
input for air quality and particle dispersion modelling near highways and in
Citation: Wang, F., Ketzel, M., Ellermann, T., Wåhlin, P., Jensen, S. S., Fang, D., and Massling, A.: Particle number, particle mass and NOx emission factors at a highway and an urban street in Copenhagen, Atmos. Chem. Phys., 10, 2745-2764, doi:10.5194/acp-10-2745-2010, 2010.