Steinar Larssen

Origin and patterns of distribution of trace elements in street dust: Unleaded petrol and urban lead

The elemental composition, patterns of distribution and possible sources of street dust are not common to all urban environments, but vary according to the peculiarities of each city. The common features and dissimilarities in the origin and nature of street dust were investigated through a series of studies in two widely different cities, Madrid (Spain) and Oslo (Norway), between 1990 and 1994. The most comprehensive sampling campaign was carried out in the Norwegian capital during the summer of 1994. An area of 14 km2, covering most of downtown Oslo and some residential districts to the north of the city, was divided into 1 km2 mapping units, and 16 sampling increments of approximately 150 g were collected from streets and roads in each of them. The fraction below 100 μm was acid-digested and analysed by ICP-MS. Statistical analyses of the results suggest that chemical elements in street dust can be classified into three groups: “urban” elements (Ba, Cd, Co, Cu, Mg, Pb, Sb, Ti, Zn), “natural” elements (Al, Ga, La, Mn, Na, Sr, Th, Y) and elements of a mixed origin or which have undergone geochemical changes from their original sources (Ca, Cs, Fe, Mo, Ni, Rb, Sr, U). Soil resuspension and/or mobilisation appears to be the most important source of “natural” elements, while “urban” elements originate primarily from traffic and from the weathering and corrosion of building materials. The data for Pb seem to prove that the gradual shift from leaded to unleaded petrol as fuel for automobiles has resulted in an almost proportional reduction in the concentration of Pb in dust particles under 100 μm. This fact and the spatial distribution of Pb in the city strongly suggest that lead sources other than traffic (i.e. lead accumulated in urban soil over the years) may contribute as much lead, if not more, to urban street dust.

European survey for NOx emissions with emphasis on Eastern Europe

Abstract Emission estimates are presented for NO x from stationary and mobile sources in Europe with particular eempasis on Eastern Europe. Total emissions of NO x in Europe were estimated to 23.9 × 10 6 as NO 2 in 1985 with a ca 50 per cent contribution from Eastern Europe. The calculated emissions were based on the emission factors proposed in this work, and on statistical data. The proposed emission factors were country specific for stationary sources in Eastern Europe. For mobile sources, uniform emission factors for each vehicle type and driving mode were used for all countries. For stationary sources in Western Europe, the emission figures from OECD were used. The NO x emissions from stationary sources in Europe were calculated to be equal to the NO x emissions from mobile sources in Europe. The contribution of NO x emissions from stationary sources in Eastern Europe was, however, 60 per cent, and for Western Europe, 40 per cent. The spatial distribution of NO x emissions in Europe is also shown in the EMEP grid system of 150 km × 150 km . The NO x emission factors and the NO x emissions in Eastern Europe were then compared with estimates from the EMEP programme and with data from national authorities in Eastern Europe. Good agreement was obtained for the G.D.R., Hungary and, to some extent, Poland. The largest differences were found for the U.S.S.R., Albania, Bulgaria, Romania and Yugoslavia. Natural emissions of NO x in Europe were also estimated and it was suggested that they are not significant (below 3 per cent) compared to anthropogenic emissions. The following can be recommended: (1) a unified methodology to calculate NO x emission factors; (2) a handbook of NO x emission factors; (3) an atlas of major point sources in Europe, and (4) a methodology to calculate accuracy of NO x emission estimates.

Cost benefit analysis of European air quality targets for sulphur dioxide, nitrogen dioxide and fine and suspended particulate matter in cities

The European Commission has proposed air quality standards for NO2, SO2 and PM10 to be in force by 2010. The present paper presents a study that gauged their costs and benefits. An analysis of the expected emissions for 2010 (reference emission scenario), using simplified air quality models, showed that non-compliance with these standards will occur in cities only, not in rural areas. Most compliance problems are expected for PM10, least for SO2. Central estimates of the costs to meet standards range from 21 MECU (SO2), to 79 MECU (NO2) to 87--225 MECU (PM10). The estimated benefits are 83--3783 MECU (SO2), 408--5900 MECU (NO2), and 5007--51247 MECU (PM10). Uncertainties are high, due to errors and incertitude in various steps of the methodology, mainly the estimation of the human health effects, in particular effects on mortality, and in the valuation of a statistical life. In the case of PM10, additional uncertainty results from the small size of the air quality database. Notwithstanding the uncertainties, the indications are that the benefits exceed the costs.

Measurements of particulate matter within the framework of the European Monitoring and Evaluation Programme (EMEP): I. First results

Particulate matter (PM) monitoring presents a new challenge to the transboundary air pollution strategies in Europe. Evidence for the role of long-range transport of particulate matter and its significant association with a wide range of adverse health effects has urged for the inclusion of particulate matter within the European Monitoring and Evaluation Programme (EMEP) framework. Here we review available data on PM physico-chemical characteristics within the EMEP framework. In addition we identify future research needs for the characterisation of the background PM in Europe that include detailed harmonised measurements of mass, size and chemical composition (mass closure) of the ambient aerosol.

Air pollution exposure monitoring and estimating. Part I. Integrated air quality monitoring system

This paper presents an integrated exposure monitoring system, based on an expansion of existing air quality monitoring systems using dispersion modelling. The system allows: (1) identifying geographical areas whose inhabitants are most exposed to ambient pollution; (2) identifying how many people in an area are exposed to concentrations of pollution exceeding air quality guidelines; (3) describing the exposure of population subgroups (e.g. children); (4) planning pollution abatement measures and quantifying their effects; (5) establishing risk assessment and management programs, and (6) investigating the short- and long-term effects of both pollutants and pollution sources on public health. The effect of pollution is rarely very large and in order to discover it, exposure estimation must provide data that reflects both spatial and temporal variations. Estimates of pollution exposure are obtained using an integrated approach that combines results of measurements from monitoring programs with dispersion calculations. These values can serve as estimates for individual short-term or long-term exposure. The grouped data allows the expression of ambient pollution concentrations as the spatial distribution of estimates such as the mean or 98th percentile of such compounds as SO2, O3, NO2, PM10 and PM2.5. This integrated approach has been combined into a single software package, AirQUIS.

Air pollution exposure monitoring and estimation. Part V. Traffic exposure in adults

In Oslo, traffic has been one of the dominating sources of air pollution in the last decade. In one part of the city where most traffic collects, two tunnels were built. A series of before and after studies was carried out in connection with the tunnels in use. Dispersion models were used as a basis for estimating exposure to nitrogen dioxide and particulate matter in two fractions. Exposure estimates were based on the results of the dispersion model providing estimates of outdoor pollutant concentrations on an hourly basis. The estimates represent concentrations in receptor points and in a square kilometre grid. The estimates were used to assess development of air pollution load in the area, compliance with air quality guidelines, and to provide a basis for quantifying exposure-effect relationships in epidemiological studies. After both tunnels were taken in use, the pollution levels in the study area were lower than when the traffic was on the surface (a drop from 50 to 40 micrograms m-3). Compliance with air quality guidelines and other prescribed values has improved, even if high exposures still exist. The most important residential areas are now much less exposed, while areas around tunnel openings can be in periods exposed to high pollutant concentrations. The daily pattern of exposure shows smaller differences between peak and minimum concentrations than prior to the traffic changes. Exposures at home (in the investigation area) were reduced most, while exposures in other locations than at home showed only a small decrease. Highest hourly exposures are encountered in traffic.

The Operational Street Pollution Model (OSPM)

A new model for estimating dispersion of air pollution from traffic in street canyons has recently been developed (Hertel and Berkowicz, 1989a). This model is named the Operational Street Pollution Model (OSPM). OSPM contains also a chemical submodel describing formation af NO2 in street canyons (Hertel and Berkowicz, 1989b).

A model for car exhaust exposure calculations to investigate health effects of air pollution.

This paper presents a model for car exhaust exposure calculations, which improves the air pollution exposure estimates necessary to study relationships between health and air pollution. The model enables calculation of hour-by-hour air pollution concentrations at receptor points in an area. Combined with a diary method, in which participants in the study give data on their movement in the area, the model enables personal air pollution exposure values to be calculated. The paper shows examples of comparison between measured and calculated exposure.

Verification of Urban Scale Time-Dependent Dispersion Model with Subgrid Elements, in Oslo, Norway

Results from monitoring of air pollution concentrations in cities in Norway have shown that nitrogen dioxide (NO2) is one of the compounds which most often, and to the largest extent, exceeds current air quality guidelines (Hagen, 1992; Larssen, 1993). This is the case both in city streets and in the urban atmosphere in general. In Norway, the highest NO2 concentrations occur during the winter months, in connection with “episodes” with poor dispersion. In the general urban atmosphere, high 24-hour average values are of greatest concern relative to Air Quality Guideline (AQG), while in the street atmosphere, very high peak (hourly) concentrations may be the most important problem.

Recommendations for the spatial assessment of air quality resulting from the FP6 EU project Air4EU

Air4EU is an FP6 European project with the major aim of providing recommendations on methodologies for the spatial assessment of air quality on local, urban and regional scales. The emphasis is on methodologies that combine monitoring and modelling and on spatial assessment for regulatory purposes, i.e., the EU daughter directives. The recommendations coming from Air4EU are intended as guidance for authorities involved in air quality assessment at the city, national and European levels as well as institutes involved in air quality research and application. This paper provides some highlights from the recommendations and case studies that emerged from the project.