Tarja Koskentalo

Finnish Meteorological Institute, Helsinki, Southern Finland Province, Finland

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Publications (51)109.85 Total impact

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    ABSTRACT: A mathematical model is presented for the determination of human exposure to ambient air pollution in an urban area; the model is a refined version of a previously developed mathematical model EXPAND (EXposure model for Particulate matter And Nitrogen oxiDes). The model combines predicted concentrations, information on people's activities and location of the population to evaluate the spatial and temporal variation of average exposure of the urban population to ambient air pollution in different microenvironments. The revisions of the modelling system containing the EXPAND model include improvements of the associated urban emission and dispersion modelling system, an improved treatment of the time-use of population, and better treatment for the infiltration coefficients from outdoor to indoor air. The revised model version can also be used for evaluating intake fractions for various pollutants, source categories and population subgroups. We present numerical results on annual spatial concentration, time activity and population exposures to PM2.5 in the Helsinki Metropolitan Area and Helsinki for 2008 and 2009, respectively. Approximately 60% of the total exposure occurred at home, 17% at work, 4% in traffic and 19% in other micro-environments. The population exposure originated from the long range transported background concentrations was responsible for a major fraction, 86%, of the total exposure. The largest local contributors were vehicular emissions (12%) and shipping (2%).
    03/2014; 7(2).
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    ABSTRACT: Four measurement campaigns by a mobile laboratory van were performed in two different environments; inside the harbour areas in the city center of Helsinki and along the narrow shipping channel near the city of Turku, Finland, during the winter and summer conditions in 2010-2011. The characteristics of gaseous (CO, CO2, SO2, NO, NO2, NOx) and particulate (number and volume size distributions as well as PM2.5) emissions for 11 ships regularly operating on the Baltic Sea were studied to determine the emission parameters. The highest particle concentrations were 1.5 × 106 and 1.6 × 105 cm-3 in Helsinki and Turku, respectively, and the particle number size distributions had two modes. The dominating mode was peaking at 20-30 nm and the accumulation mode at 80-100 nm. The majority of the particle mass was volatile since after heating the sample to 265 °C, the particle volume of the studied ships decreased by around 70%. The emission factors for NOx varied in the range of 25-100 g (kg fuel)-1, for SO2 in the range of 2.5-17.0 g (kg fuel)-1, for particle number in the range of (0.32-2.26) × 1016 particles (kg fuel)-1, and for PM2.5 between 1.0-4.9 g (kg fuel)-1. The ships equipped with SCR had lowest NOx emissions whereas the ships with DWI and HAM had lowest SO2 emissions but highest particulate emissions. For all ships the averaged fuel sulphur contents (FSCs) were less than 1% (by mass) but none of those was below 0.1% which will be the new EU directive from 1 January 2015 in the SOx Emission Control Areas, indicating big challenges for ships operating on the Baltic Sea.
    Atmospheric Measurement Techniques Discussions. 08/2013; 6(4):7149-7184.
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    ABSTRACT: We have developed a modelling system for predicting the traffic volumes, emissions from stationary and vehicular sources, and atmospheric dispersion of pollution in an urban area. A companion paper addresses model development and its applications. This paper describes a comparison of the predicted NOx and NO2 concentrations with the results of an urban air quality monitoring network. We performed a statistical analysis concerning the agreement of the predicted and measured hourly time series of concentrations, at four monitoring stations in the Helsinki metropolitan area in 1993. The predicted and measured NO2 concentrations agreed well at all the stations considered. The agreement of model predictions and measurements for NOx and NO2 was better for the two suburban monitoring stations, compared with the two urban stations, located in downtown Helsinki.
    Atmospheric Environment 07/2013; · 3.11 Impact Factor
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    ABSTRACT: Atmospheric fine particle black carbon (BC) was measured close to downtown of Helsinki, during November 1996–June 1997. The average BC concentrations were 1.5 μg m−3 for working days, 1.2 μg m−3 for Saturdays, and about 1 μg m−3 for Sundays and public holidays. The overall average BC concentration was equal to 1.38 μg m−3 and its average contribution to fine particle mass equal to 19%. On working days BC concentrations showed a clear diurnal variation with the highest hourly average values occurring during the morning (2.7 μg m−3) and evening (1.9 μg m−3) rush hours. Contribution of the long-range transport to the BC was estimated to be on average about 0.4 μg m−3, which is believed to represent the average regional background over southern Finland. However, this transport was very different from different geographical regions: from the densely populated areas of East- and Central-Europe it was about 0.8 μg m−3, while in northerly and northwesterly air masses it was only about 0.15 μg m−3. Local traffic was by far the most important local BC source contributing about 63, 54 and 44% on working days, Saturdays and Sundays, respectively. Other local sources were largely masked by the traffic and their contribution was estimated roughly to be of the order of 10%. The rest of BC was attributed to long-range transport.
    Atmospheric Environment 07/2013; 34(9):1497–1506. · 3.11 Impact Factor
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    ABSTRACT: Citizens are increasingly aware of the influence of environmental and meteorological conditions on the quality of their life. This results in an increasing demand for personalized environmental information, i.e., information that is tailored to citizens’ specific context and background. In this demonstration, we present an environmental information system that addresses this demand in its full complexity in the context of the PESCaDO EU project. Specifically, we will show a system that supports submission of user generated queries related to environmental conditions. From the technical point of view, the system is tuned to discover reliable data in the web and to process these data in order to convert them into knowledge, which is stored in a dedicated repository. At run time, this information is transferred into an ontology-based knowledge base, from which then information relevant to the specific user is deduced and communicated in the language of their preference.
    Extended Semantic Web Conference (ESWC) 2012; 05/2012
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    Artificial Intelligence Applications and Innovations, IFIP Advances in Information and Communication Technology; 01/2012
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    ABSTRACT: Citizens are increasingly aware of the influence of environmental and meteorological conditions on the quality of their life. This results in an increasing demand for personalized environmental information, i.e., information that is tailored to citizens’ specific context and background. In this work we describe the development of an environmental information system that addresses this demand in its full complexity. Specifically, we aim at developing a system that supports submission of user generated queries related to environmental conditions. From the technical point of view, the system is tuned to discover reliable data in the web and to process these data in order to convert them into knowledge, which is stored in a dedicated repository. At run time, this information is transferred into an ontology-structured knowledge base, from which then information relevant to the specific user is deduced and communicated in the language of their preference.
    Environmental Software Systems. Frameworks of eEnvironment - 9th IFIP WG 5.11 International Symposium, ISESS 2011, Brno, Czech Republic, June 27-29, 2011. Proceedings; 01/2011
  • Proceedings of ENVIP'2010 Workshop at EnviroInfo2010; 01/2010
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    ABSTRACT: The frequency, strength and sources of long-range transport (LRT) episodes of fine particles (PM2.5) were studied in southern Finland using air quality monitoring results, backward air mass trajectories, remote sensing of fire hot spots, transport and dispersion modelling of smoke and chemical analysis of particle samples (black carbon, monosaccharide anhydrides, oxalate, succinate, malonate, SO42−, NO3−, K+ and NH4+). At an urban background site in Helsinki, the daily WHO guideline value (24-h PM2.5 mean 25 μg m−3) was exceeded during 1–7 LRT episodes per year in 1999–2007. The 24-h mean maximum concentrations varied between 25 and 49 μg m−3 during the episodes, which was 3–6 times higher than the local mean concentration (8.7 μg m−3) in 1999–2007. The highest particle concentrations (max. 1-h mean 163 μg m−3) and the longest episodes (max. 9 days) were mainly caused by the emissions from open biomass burning, especially during springs and late-summers in 2002 and 2006. During the period 2001–2007, the satellite remote sensing of active fire hot spots and transport and dispersion modelling of smoke indicated that approximately half of the episodes were caused partly by the emissions from wildfires and/or agricultural waste burning in fields in Eastern Europe, especially in Russia, Belarus and Ukraine. Other episodes were mainly caused by the LRT of ordinary anthropogenic pollutants, e.g. from energy production, traffic, industry and wood combustion. During those ‘other episodes’, air masses also arrived from Eastern Europe, including Poland. The highest concentrations of biomass-burning tracers, such as monosaccharide anhydrides (levoglucosan + mannosan + galactosan) and K+, were observed during open biomass-burning episodes, but quite high values were also measured during some winter episodes due to wood combustion emissions. Our results indicate that open biomass burning in Eastern Europe causes high fine particle concentration peaks in large areas of Europe almost every year.
    Atmospheric Environment. 01/2009;
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    ABSTRACT: We present a modelling system that contains a treatment of the emissions and atmospheric dispersion of fine particulate matter (PM2.5) on an urban scale, combined with a statistical model for estimating the contribution of long-range transported aerosols. The model of PM2.5 emissions includes exhaust emissions, cold starts and driving, as well as, non-exhaust emissions originated from urban vehicular traffic. The influence of primary vehicular emissions from the road and street network was evaluated using a roadside emission and dispersion model, CAR-FMI, in combination with a meteorological pre-processing model, MPP-FMI. We have computed hourly sequential time series of the PM2.5 concentrations in 2002 in a numerical grid in the Helsinki Metropolitan Area. The predicted results were compared against measured data at two locations in central Helsinki: urban roadside station of Vallila and urban background station of Kallio. The predicted daily average PM2.5 concentrations agreed well with the measured values; e.g., the index of agreement values were 0.83 and 0.86 at Vallila and Kallio, respectively, and the absolute values of fractional bias ⩽0.13. As expected, the scatter of data points is substantially wider for the hourly concentration values; e.g., the index of agreement values were 0.69 and 0.74. We also computed the spatial concentration distributions of PM2.5. The predicted contribution from long-range transport to the street level PM2.5 varied spatially from 40% in the most trafficked areas to nearly 100% in the outskirts of the area. The emissions originated from cold starts and driving were responsible for
    Atmospheric Environment 01/2008; 42(19):4517-4529. · 3.11 Impact Factor
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    ABSTRACT: In this study, we developed two methods to distinguish the long-range transport (LRT) episodes from local pollution (LP) episodes. The first method is based on particle number concentrations ratio between accumulation mode (diameter >90 nm) and Aitken mode (diameter 25–90 nm). The second method is based on a proxy variable (interpolated ion sum) for long-range transported PM2.5. The ion-sum is available from the measurements of sulphate, nitrate and ammonium at the nearest EMEP stations. We also utilised synoptic meteorological weather charts, locally measured meteorological data, and air mass back-trajectories to support the evaluation of these methods. We selected nine time periods (i.e. episodes) with daily average PM10>50 μg m−3 in the Helsinki Metropolitan Area during year 2002. We characterized the episodes in terms of PM10 and PM2.5 concentrations and the fraction of fine particles in PM10 at an urban traffic and regional background air quality monitoring sites. Three of these episodes were clearly of local origin. They were characterized by a low average fraction of PM2.5 (<0.2) in PM10 at the urban traffic monitoring site, low ratio between PM10 concentrations at the regional background site and at the urban traffic site (<0.2), low average ion sums (1.5–2.5 μg m−3) and low accumulation to Aitken mode ratios (0.13–0.26). Four of the episodes had distinct LRT characteristics: a high fraction of fine particles in PM10 (0.5–0.6) at the urban traffic site, a high ratio between PM10 concentrations at the regional background site and at the urban traffic site (0.7–0.8), high interpolated values for the ion sum (6.6–11.9 μg m−3), and high accumulation to Aitken mode ratios (0.75–0.85). During the remaining two episodes there was significant contribution from both local sources and LRT. A detailed analysis of meteorological variables and air mass back-trajectories gave support to these findings. These characteristics can be utilised in a simple procedure to distinguish between LRT and LP episodes. Further quantitative investigations to these characteristics provide an indication to the episode strength. The quantitative results presented in the current study are applicable to the Helsinki Metropolitan Area and similar cities. Nevertheless, developing these methods for other cities require analyses of the meteorological conditions, behavior of the PM concentrations, and air-mass back trajectories for that specific city.
    Atmospheric Environment 01/2008; · 3.11 Impact Factor
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    ABSTRACT: Daily variation in outdoor concentrations of inhalable particles (PM(10) <10 microm in diameter) has been associated with fatal and nonfatal stroke. Toxicological and epidemiological studies suggest that smaller, combustion-related particles are especially harmful. We therefore evaluated the effects of several particle measures including, for the first time to our knowledge, ultrafine particles (<0.1 microm) on stroke. Levels of particulate and gaseous air pollution were measured in 1998 to 2004 at central outdoor monitoring sites in Helsinki. Associations between daily levels of air pollutants and deaths caused by stroke among persons aged 65 years or older were evaluated in warm and cold seasons using Poisson regression. There was a total of 1304 and 1961 deaths from stroke in warm and cold seasons, respectively. During the warm season, there were positive associations of stroke mortality with current- and previous-day levels of fine particles (<2.5 microm, PM(2.5)) (6.9%; 95% CI, 0.8% to 13.8%; and 7.4%; 95% CI, 1.3% to 13.8% for an interquartile increase in PM(2.5)) and previous-day levels of ultrafine particles (8.5%; 95% CI, -1.2% to 19.1%) and carbon monoxide (8.3; 95% CI, 0.6 to 16.6). Associations for fine particles were mostly independent of other pollutants. There were no associations in the cold season. Our results suggest that especially PM(2.5), but also ultrafine particles and carbon monoxide, are associated with increased risk of fatal stroke, but only during the warm season. The effect of season might be attributable to seasonal differences in exposure or air pollution mixture.
    Stroke 04/2007; 38(3):918-22. · 6.16 Impact Factor
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    ABSTRACT: The performance of a modified Harvard high-volume cascade impactor (HVCI) was evaluated in six field campaigns with size-segregated particulate samplings for chemical and toxicological characterization. The 7-week sampling campaigns in 2002-2003 in Duisburg (autumn), Prague (winter), Amsterdam (winter), Helsinki (spring), Barcelona (spring), and Athens (summer) were selected to represent contrasting urban environments and seasons of public health interest due to high particulate concentrations or previous findings in epidemiological studies. Particulate samples were collected in parallel with the HVCI (PM(10-2.5), PM(2.5-1), PM(1-0.2), PM(0.2)), a virtual impactor (VI; PM(10-2.5), PM(2.5)), and a Berner low-pressure impactor (BLPI; 10 stages between 0.035 and 10 mum in particle diameter) using a 3- or 4-day sampling duration. The campaigns exhibited different profiles with regard to particulate mass concentration, size distribution, chemical composition and meteorological conditions, thus providing a demanding setup for an overall field comparison of the HVCI with the VI and BLPI reference samplers. Size-segregated particulate mass concentration could be reasonably well measured with the present HVCI configuration. The coarse (PM(10-2.5)) and fine (PM(2.5)) particulate mass agreed within 10% with the low-volume reference samplers, and the four-stage size distribution of the HVCI followed the modal pattern of urban aerosol. The concentrations of chemical constituents measured and integrated especially for the HVCI-PM(2.5) differed to some extent from those measured from the corresponding VI-PM(2.5) samples. This implies that when investigating the association of toxicological responses with the chemical constituents of particulate matter, it is necessary to use the chemical composition data of the same samples as used in toxicological experiments.
    Science of The Total Environment 04/2007; 374(2-3):297-310. · 3.26 Impact Factor
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    ABSTRACT: Traffic particles, total number concentration and size distribution in the range 3 nm–10 μm, as well as concentrations of carbon monoxide and nitrogen oxides were measured by a mobile laboratory at a major highway and in its vicinity, 0–140 m from the road side, in Helsinki, during the summer and winter campaigns in 2003 and 2004. The data have been analysed according to the sampling point and temperature, and classified to three wind sectors; wind blowing perpendicular to the road from northwest (S1) or to the opposite direction (S3), and wind blowing along the road (S2). The average concentrations in winter were 2–3 times higher than the concentrations in summer. In winter, 90–95%, and in summer, 86–90% of particles were smaller than 50 nm. The equations for the concentration curves in sectors S1 and S2 were derived, starting point being at the roadside. When moving 65 m from the roadside, the average concentration reduced to 39% in winter and to 35% in summer in wind sector S1 whilst in sector S2, it already decreased to 19% in summer. The size distributions showed 2–3 modes peaking at 14–23 nm (nucleation mode), 40–50 nm (Aitken mode) and 120–125 nm (accumulation mode). In wind sector S1, in winter, the nucleation mode shifted to larger sizes when moving away from the road.
    Atmospheric Environment. 01/2006;
  • EPIDEMIOLOGY. 01/2006; 17(6, S):S57-S58.
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    ABSTRACT: Special episodes of long-range transported particulate (PM) air pollution were investigated in a one-month field campaign at an urban background site in Helsinki, Finland. A total of nine size-segregated PM samplings of 3- or 4-day duration were made between August 23 and September 23, 2002. During this warm and unusually dry period there were two (labelled P2 and P5) sampling periods when the PM2.5 mass concentration increased remarkably. According to the hourly-measured PM data and backward air mass trajectories, P2 (Aug 23-26) represented a single, 64-h episode of long-range transported aerosol, whereas P5 (Sept 5-9) was a mixture of two 16- and 14-h episodes and usual seasonal air quality. The large chemical data set, based on analyses made by ion chromatography, inductively coupled plasma mass spectrometry, X-ray fluorescence analysis and smoke stain reflectometry, demonstrated that the PM2.5 mass concentrations of biomass signatures (i.e. levoglucosan, oxalate and potassium) and of some other compounds associated with biomass combustion (succinate and malonate) increased remarkably in P2. Crustal elements (Fe, Al, Ca and Si) and unidentified matter, presumably consisting to a large extent of organic material, were also increased in P2. The PM2.5 composition in P5 was different from that in P2, as the inorganic secondary aerosols (NO3-, SO4(2-), NH4+) and many metals reached their highest concentration in this period. The water-soluble fraction of potassium, lead and manganese increased in both P2 and P5. Mass size distributions (0.035-10 microm) showed that a large accumulation mode mainly caused the episodically increased PM2.5 concentrations. An interesting observation was that the episodes had no obvious impact on the Aitken mode. Finally, the strongly increased concentrations of biomass signatures in accumulation mode proved that the episode in P2 was due to long-range transported biomass combustion aerosol.
    Science of The Total Environment 12/2005; 350(1-3):119-35. · 3.26 Impact Factor
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    ABSTRACT: Fine particulate matter (PM2.5) and particle number concentrations were monitored in the Helsinki subway system during a two-weeks’ measurement campaign in March 2004. The PM2.5 samples was analysed for elemental composition and carbon fraction. The average daytime PM2.5 concentrations were 47 (±4) and 60 (±18) μg m−3 at the two underground subway stations and 19 (±6) and 21 (±4) μg m−3 at a ground level station and in subway cars, respectively. For the same measurement period, the corresponding PM2.5 concentrations at the urban background and street canyon monitoring sites were 10 (±7) and 17 (±10) μg m−3.The particle number (D<500 nm) concentrations and size distributions at the underground subway station were very similar to those measured at the urban background monitoring site indicating that the source of particles of this size is street traffic. The average daytime particle number concentration was 31 000 (±14 000) particles cm−3 compared to 27 000 (±17 000) particles cm−3 at an urban background monitoring site (D<320 nm). The average daytime black carbon concentration was 6.3 (±1.8) μg m−3, the concentration of elemental carbon 4.0 (±2.0) and organic carbon 7.4 (±1.6) μg m−3.The most enriched element in PM2.5 samples was iron, the concentration of which ranged from 0.7 (±0.3) μg m−3 at the ground level subway station to 29 (±7) μg m−3 at the underground subway station. Other enriched elements included Mn, Cr, Ni, and Cu. We calculated that 30 min commuting +9 min stay at the stations per day increased the exposure to PM2.5 mass by only approximately 3% compared to staying in urban traffic environment, but the exposure to iron in PM2.5 increased nearly 200%, to Mn 60%, and to Cu 40%.
    Atmospheric Environment. 09/2005;
  • Atmospheric Chemistry and Physics 01/2005; 5:2299-2310. · 4.88 Impact Factor
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    ABSTRACT: We studied the sources, compositions and size distributions of aerosol particles during long-range transport (LRT) PM2.5 episodes occurred on 12–15 August, 26–28 August and 5–6 September 2002 in Finland. Backward air mass trajectories, satellite detections of fire areas, and dispersion modelling results indicate that emissions from wildfires in Russia and other Eastern European countries arrived to Finland during the episodes. Individual particle analyses using scanning electron microscopy (SEM) coupled with energy dispersive X-ray analyses (EDX) showed that the proportion of S-rich particles increased during the episodes and they contained elevated fractions of K, which indicates emissions from biomass burning. These aerosols were mixed with S-rich emissions from fossil fuel burning during the transport, since air masses came through polluted areas of Europe. Minor amounts of coarse Ca-rich particles were also brought by LRT during the episodes, and they probably originated from wildfires and/or from Estonian and Russian oil-shale burning industrial areas. The ion chromatography analysis showed that concentrations of sulphate (SO42-), total nitrate (NO3-+HNO3(g)) and total ammonium (NH4++NH3(g)) increased during the episodes, but the ratio of total amount of these ions to PM10 concentration decreased indicating unusually high fractions of other chemical components. The particle number size distribution measurements with differential mobility particle sizer (DMPS) showed that the concentrations of 90–500 nm particles increased during the episodes, but the concentrations of particles smaller than 90nm decreased. The reduction of the smallest particles was caused by suppressed new particle formation due to the vapour and molecular cluster uptake of LRT particles. Our results show that the emissions from wildfires in Russian and other Eastern European deteriorated air quality on very large areas, even at the distance of over 1000 km from the fire areas.
    Atmospheric Chemistry and Physics 01/2005; · 4.88 Impact Factor
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    ABSTRACT: We studied the sources, compositions and size distributions of aerosol
    Atmospheric Chemistry and Physics 01/2005; 5:-2310. · 5.51 Impact Factor