Finn Palmgren

Experimental studies of ultrafine particles in streets and the relationship to traffic

Abstract Fine and ultrafine particles are of great concern due to their adverse health effects. Furthermore, the emission of ultrafine particles has been reported to be increasing even if the total mass of particles emitted from vehicles decreases. Determination of emission factors of ultrafine particles from the actual car fleet for different types of vehicles is essential for reliable model calculations of the directly emitted particles from the traffic. The present study includes test of measurement methods and analysis of field data from Copenhagen. Measurements of fine and ultrafine particles were carried out during winter/spring 1999, at street level in central Copenhagen, at roof level in Copenhagen, and at street level in the city Odense. The measurements were carried out by differential mobility analyser (DMA) with a high-time resolution corresponding to the variation in traffic and meteorology. The particles were separated into 29 size fractions from 0.01 to 0.7 μm. Significant correlation at street level was observed between the CO, NO x , and ultrafine particles, indicating that the traffic is the major source of ultrafine particles in the air. Time series for several months of the size distributions have been analysed using statistical methods. Factor analysis has been used for the identification of the important sources, and a constrained linear receptor model has been used for source apportionment and for the determination of single-source size distributions of ultrafine particles from diesel- and petrol-fuelled vehicles.

Using measurements of air pollution in streets for evaluation of urban air quality : meterological analysis and model calculations

Measurements of urban air pollution are usually confined to a few locations within a city area. Monitoring stations are often situated in streets with significant traffic levels or in places where severe pollution problems are expected. Such measurements are naturally influenced by very local conditions and care must be taken in interpreting the results. This is especially important when the measurements are used for estimating urban air pollution levels or comparing air quality in different cities. Another frequent application of street measurements is for public information or warning the population of elevated pollution levels. Estimating the dangers of long-term exposure to air pollution means careful consideration must be given to how representative these measurements actually are. In this paper the influence of local conditions on air pollution concentrations is discussed, regarding especially the dependency of pollution levels on street configuration and meteorolgical parameters. The examples used are based on measurements from locations in Copenhagen and on model calculations using the Danish Operational Street Pollution Model (OSPM). It is shown that large concentration gradients can occur in street canyons with leeward concentrations far higher than windward concentrations. Thus, street measurements are site-dependent and not representative for urban areas. Model calculations with OSPM agree well with measurements.

Actual car fleet emissions estimated from urban air quality measurements and street pollution models.

A method to determine emissions from the actual car fleet under realistic driving conditions has been developed. The method is based on air quality measurements, traffic counts and inverse application of street air quality models. Many pollutants are of importance for assessing the adverse impact of the air pollution, e.g. NO2, CO, lead, VOCs and particulate matter. Aromatic VOCs are of special great concern due to their adverse health effects. Measurements of benzene, toluene and xylenes were carried out in central Copenhagen since 1994. Significant correlation was observed between VOCs and CO concentrations, indicating that the petrol engine vehicles are the major sources of VOC air pollution in central Copenhagen. Hourly mean concentrations of benezene were observed to reach values of up to 20 ppb, what is critically high according to the WHOs recommendations. Based on inverse model calculation of dispersion of pollutants in street canyons, an average emission factor of benzene for the fleet of petrol fuelled vehicles was estimated to be 0.38 g/km in 1994 and 0.11 in 1997. This decrease was caused by the reduction of benzene content in Danish petrol since summer 1995 and increasing percentage of cars equipped with three-way catalysts. The emission factors for benzene for diesel-fuelled vehicles were low.

Urban air pollution : European aspects

Preface. I: Statement of the Problem. 1. About the Book J. Fenger, et al. 2. History of Urban Air Pollution P. Brimblecombe. 3. Europe and its Cities K.E. Gronskei. II: Urban Sources of Air Pollution. 4. Stationary Sources J.E. Johnsson. 5. Mobile Sources Z. Samaras, S.P. Sorensen. 6. Emission Inventories R. Friedrich, U.-B. Schwarz. III: Basic Atmospheric Phenomena. 7. Dynamical and Thermal Processes K.E. Gronskei. 8. Transformation of Air Pollutants R.G. Derwent, O. Hertel. 9. Particles H. Horvath. IV: Air Pollution Modelling. 10. Regional/Mesoscale Models G. Kallos. 11. Urban Scale Models P.G. Mestayer. 12. Street Scale Models R. Berkowicz. 13. Stochastic Models O. Herbarth, et al. 14. Wind Tunnel Experiments M. Schatzmann, et al. V: Air Quality Measurements. 15. Measurement Techniques I. Allegrini. 16. Monitoring Networks and Air Quality Management Systems S. Larssen. 17. Quality Assurance and Quality Control S. Larssne, C. Helmis. VI: Impacts of Urban Air Pollution. 18. Health Impacts O. Herbarth. 19. Materials Damage J. Tidblad, V. Kucera. 20. Impacts on Urban Vegetation and Ecosystems M. Ashmore. 21. Reduction of Visibility H. Horvath. VII: Policies, Legislation -- and a Final Overview. 22. Policies to Reduce Urban Air Pollution S. Krawack. 23. Air Quality Indicators P. Wiederkehr, S.-J. Yoon. 24. Limit Values L. Edwards. 25. Air Pollution in European Cities -- An Overview L. Bozo, et al. 26. Summary and Conclusions J. Fenger, et al. Index.

Operational air pollution forecasts from European to local scale

Abstract A new operational air pollution forecast system, THOR, has been developed at the National Environmental Research Institute, Denmark. The integrated system consists of a series of air pollution models, covering a wide range of scales (from European scale to street scale in cities) and applications. The system is designed to automatically produce 3 days air pollution forecasts of the most important air pollution species on different scales on a continuous basis. The various models, the coupling/integration and the configuration of the models, the visualizations and the real-time performance on fast workstations with parallel architecture will be described. Some examples of model results and validations on street level are presented.

Human exposure to outdoor air pollution (IUPAC Technical Report)

Human exposure to outdoor air pollution is believed to cause severe health effects, especially in urban areas where pollution levels often are high, because of the poor dispersion conditions and high density of pollution sources. Many factors influence human health, and a good assessment of human air pollution exposure is, therefore, crucial for a proper determination of possible links between air pollution and health effects. Assessment of human exposure is, however, not straightforward, and this is the background for the present paper, which recommends how to carry out such assessments. Assessment of human exposure to air pollution may be carried out by use of: categorical classification, application of biomarkers, analysis of air pollution data from routine monitoring networks, personal portable exposure monitors, or application of mathematical air pollution exposure models. The categorical classification is a crude indirect method based on indicators of exposure such as type of residence, type of job, presence of indoor sources, etc. Categorical classification is generally inadequate for application in air pollution epidemiology. Biomarkers can be a strong instrument in assessment of health effects and provide information about air pollution exposure and dose. Use of biomarkers is, therefore, particularly useful when applied in combination with exposure assessment through one of the methods 3 to 5. The main focus of this paper is on these three methods for determination of human air pollution exposure. The optimal solution is clearly a combination of methods 2 to 5, but the available resources often set a limit to how far the assessment is carried out, and the choice of strategy will, therefore, often be very important for the outcome of the final study. This paper describes how these approaches may be applied and outlines advantages and disadvantages of the approaches used individually and in combination. Furthermore, some examples of specific applications in Denmark and the Netherlands are given for illustration.

An overview of commonly used methods for measuring benzene in ambient air

Abstract Emitted primarily from traffic, benzene has been identified as a carcinogen, inflicting deleterious effects on human health. This has mandated a high degree of scientific attention, both to measure ambient levels in urban regions and to explore mitigation strategies, which can form the basis of policy. In this paper, we present an overview of the most commonly used methods for measurements of atmospheric benzene. The results from field inter-comparisons involving a BTEX monitor as well as with manual pumped tube sampling and diffusive sampling are presented. Finally, monitoring strategies are discussed.

Human exposure to traffic pollution. Experience from Danish studies

Air pollution may have severe long-term as well as short-term health effects. The determination of possible links between pollution levels and impact on human health is, however, not a straightforward task. A key problem is the assessment of human exposure to ambient pollution levels. In later years, the possible role of particulate pollution as a health hazard has drawn major attention and is, therefore, the subject of research projects in many countries including Denmark. The present paper gives a review of recent and ongoing/planned Danish air pollution exposure studies. Furthermore, key results from Danish studies of ultrafine particles from urban traffic are outlined. The exposure studies show that air pollution models may be strong tools in impact assessment studies, especially when used in combination with personal exposure monitoring and application of biomarkers. Personal exposure measurements in Copenhagen indicate that indoor pollution levels may be very important for the personal exposure to fine fraction particles (PM2.5). Measurements with a differential mobility analyzer (DMA) in Danish urban areas show that number concentrations of ultrafine particles (<100 nm) in busy streets are strongly correlated with classic traffic pollutants such as nitrogen oxides and carbon monoxide. The number concentrations in urban Danish streets have decreased considerably between two campaigns in 1999 and 2000, apparently as a result of reductions in sulfur contents in Danish diesel fuels that took place in July 1999.

Lung cancer, smoking, and environment: a cohort study of the Danish population

Abstract Objective: The almost twofold difference in lung cancer incidence between people living in Copenhagen and in the rural areas of Denmark in the 1980s led to public concern; this study was undertaken to assess the effects of air pollution and occupation on lung cancer in Denmark, with control for smoking habits. Design: Cohort study of national population. Subjects: People aged 30-64 and economically active in 1970 (927 470 men and 486 130 women). Main outcome measures: Relative risks for lung cancer estimated with multiplicative Poisson modelling of incidence rates. Results: Differences in smoking habit explained about 60% of the excess lung cancer risk in Copenhagen for men and 90% for women. After control for smoking, workers had double the lung cancer risk of teachers and academics. There was only a small independent effect of region. Conclusion: Smoking is the main factor behind the regional differences in lung cancer incidence in Denmark, and occupational risk factors also seem to have an important role. The outdoor air in Copenhagen around 1970 contained on average 50-80 µg/m3 of sulphur dioxide, 80-100 µg/m3 total suspended particulate matter, and up to 10 ng/m3 benzo(a)pyrene and had peak values of daily smoke of 120 µg/m3. Region had only a small effect on incidence of lung cancer in the present study, which suggests that an influence of outdoor air pollution on lung cancer is identifiable only above this pollution level. Key messages This cohort study of the national population shows that smoking explained about 60% of the excess lung cancer risk in Copenhagen for men and 90% for women After control for smoking, however, workers had double the cancer risk of teachers or academics, whereas there was only a small independent effect of region The outdoor air in Copenhagen around 1970 contained on average 50-80 µg/m3 of sulphur dioxide, 80-100 µg/m3 total suspended particulate matter, and up to 10 ng/m3 benzo(a)pyrene and had peak values of daily smoke of 120 µg/m3 The fact that only a small effect of region on lung cancer incidence was seen in the present study indicates that an influence of outdoor air pollution on lung cancer is identifiable only above this pollution level

Characterisation of particle emissions from the driving car fleet and the contribution to ambient and indoor particle concentrations

Abstract The population is mainly exposed to high air pollution concentrations in the urban environment, where motor vehicle emissions constitute the main source of fine and ultrafine particles. These particles can penetrate deep into the respiratory system, and studies indicate that the smaller the particle, the larger the health impacts. The chemical composition, surface reactivity and physical properties are also important. However, the knowledge about chemical and physical properties of particles and the temporal and spatial variability of the smallest particles is still very limited. The present study summarises the first results of a larger project with the aims to improve the knowledge. The concentration and the emissions of ultrafine particles from petrol and diesel vehicles, respectively, have been quantified using Scanning Mobility Particle Sizer of ultrafine particles in the size range 6–700 nm and routine monitoring data from urban streets and urban background in Denmark. The quantification was carried out using receptor modelling. The number size distributions of petrol and diesel emissions showed a maximum at 20–30 nm and non-traffic at ≈100 nm. The contribution of ultrafine particles from diesel vehicles is dominating in streets. The same technique has been applied on PM 10 , and ≈50% contribution from non-traffic. The technique has also been introduced in relation to elemental and organic carbon, and the first data showed strong correlation between traffic pollution and elemental carbon. The outdoor air quality has a significant effect on indoor pollution levels, and we spend most of the time indoors. Knowledge about the influence of ambient air pollution on the concentrations in the indoor environment is therefore crucial for assessment of human health effects of traffic pollution. The results of our studies will be included in air quality models for calculation of human exposure. Preliminary results from our first campaign showed, that the deposition rate of particles in the apartment is negligible in the particle size range 100–500 nm. In the size range below 100 nm the deposition rate increases with decreasing particle diameter to a value of approximately 1 h −1 at 10 nm. The penetration efficiency shows a maximum of 60% at 100 nm. More detailed studies of exchange of particles in outdoor/indoor air and the transformation are planned to take place during three next campaigns.