Aarhus University Seal / Aarhus Universitets segl

No. 107: Particulate pollution and health effects in the Municipality of Roskilde

Jensen, S.S., Ketzel, M. & Brandt, J. 2014. Partikelforurening og helbredseffekter i Roskilde Kommune. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 60 s. - Videnskabelig rapport fra DCE - Nationalt Center for Miljø og Energi nr. 107. http://dce2.au.dk/pub/SR107.pdf

Summary

Purpose and background

The purpose of this report is to describe air pollution and its health impacts in the Municipality of Roskilde with emphasis on particle pollution. The report is based on a synthesis and compilation of existing knowledge and data available for the Municipality of Roskilde. It is based on air quality calculations, air quality measurements and calculations of health impacts and associated external costs. The Municipality of Roskilde is located on Zealand, Denmark.

The report begins with a general description of what determines air pollution, its health effects, and the limit values set to protect public health. An air quality assessment for the Municipality of Roskilde is provided based on air quality model calculations. The spatial variation of air quality in the municipality is shown, and air quality is also described statistically. The air quality assessment also shows to what extent the air pollution in the Municipality of Roskilde can be attributed to long-range transport of air pollution, what can be attributed to the emission sources within the municipality and what can be attributed to individual streets. The total emissions for all sources in the Municipality of Roskilde are described, and the geographical distribution shown on a 1x1 km2 grid. Emission sources include road traffic, wood stoves, industry, residential heating etc. Road traffic emissions are broken down by vehicle type, Euro emission classes and fuel type based on studies from Copenhagen. Based on model results the report finally describes health effects in the form of premature deaths resulting from all air pollution in the Municipality of Roskilde, as well as the external costs resulting from air pollution.

The motivation for the project is that studies show that air pollution from all sources in Denmark and abroad in 2011 contributed to about 1,500 premature deaths a year in the Greater Copenhagen Area including the Municipality of Roskilde. There are no previous studies of prevalence of premature deaths due to air pollution in the Municipality of Roskilde, and how much local sources contribute. The Municipality of Roskilde wishes to improve the available information by funding an air quality and health impact assessment based on existing data targeting the Municipality of Roskilde.

The study will make it feasible subsequently to appoint priority areas and quantify the effects of different policy measures, but this is not part of this report.

The study

There are different contributions to air pollution. Regional air pollution is determined by all sources in Denmark and abroad. Urban background concentration is determined by the sources in the city together with the regional contributions. Air pollution in a street is determined by the vehicle traffic in the street as well as the contribution from urban background pollution. These contributions can be calculated with air quality models.

The present air quality assessment for the Municipality of Roskilde is based on data from a project called "Air quality in your street", which is a newly developed air pollution map with modelled street and urban background concentration data for all addresses in Denmark. In autumn 2014 the data is expect to become publicly available as a website where the user can navigate in the map, and it is also possible to search for a specific address. Annual mean concentrations for 2012 for NO2 (nitrogen dioxide), PM2.5 and PM10 are presented (particles less than 2.5 and 10 micro-meters in diameter, respectively). NO2 is selected for study due to problems with exceeding the limit value at a monitor station at H.C. Andersens Boulevard in Copenhagen, and because model results show a number of exceedances in Copenhagen. PM2.5 and PM10 are chosen because particles are considered to pose the greatest health impacts. The concentrations are calculated using a coupling of air quality models: DEHM (a regional chemical-transport model covering the northern hemisphere), UBM (urban background model) covering Denmark and OSPM (street model) with associated input data on emissions, meteorology, etc. Street concentrations represent concentration levels at the facade of the buildings in the street (height of 2 m). The system AirGIS generates input about traffic and street geometry for calculation points.

The emission inventory for the Municipality of Roskilde is based on data from the SPREAD model for Denmark. The SPREAD model distribute emissions from the national emission inventory for Denmark on a 1x1 km2 grid based on different geographic variables related to the different emission sources. It enables calculation of total emissions from all sources in the municipality and the spatial distribution of emissions on a grid.

A health impact assessment is carried out including 17 health effects and associated external costs based on data from calculations with the EVA model system. EVA (Economic Valuation of Air pollution) is based on Danish valuations of health effects, and calculation of external costs related to the individual emissions taking into account the geographical location of the emissions in relation to where people are. As an indicator for health effects the report presents data for premature deaths in the Municipality of Roskilde. Calculations for Copenhagen are used to assess the proportion of premature deaths and related external costs caused by emissions in the Municipality of Roskilde.

Main conclusions

Urban background concentrations

The highest NO2 urban background concentration is about twice as high as the regional background pollution. The contribution by sources in the Municipality of Roskilde to the urban background concentrations is up to about 7 µg/m3. A major source of NO2 is road traffic, and concentrations are as expected highest in Roskilde, but there are also relatively high concentrations in the north-east part of the municipality due to high contribution from wood stoves according to the model assumptions.

Urban background concentrations of PM2.5 and PM10 have a different geographic distribution than NO2 since they are not dominated by traffic. Furthermore, the regional background level is relatively high, and the local sources in the municipality contribute only a few micrograms/m3. The geographical distribution of PM2.5 and PM10 are largely similar, as they share some sources. Local sources are primarily wood stoves and traffic. In small towns in the countryside the concentrations are locally as high as the urban background concentration in Roskilde.

Street concentrations

As expected, NO2 street concentrations are highest along the major roads where traffic is a major source. These are the arterial roads, inner ring road and major distribution roads in Roskilde. The highest street contribution which is the difference between street concentrations and urban background concentrations is about 23 µg/m3. The highest NO2 concentration is about 38 µg/m3 in 2012 modelled at Jernbanegade in Roskilde, and is below the limit value of 40 µg/m3. Therefore, there are not modelled any exceedances of the limit value of NO2 in the municipality in 2012.

The geographical distribution of PM2.5 and PM10 street concentrations are similar as sources to some extent are shared. Local sources are primarily traffic and wood stoves, but the regional contribution is very large, that is, the contributions from Denmark and abroad. The highest concentrations are distributed in the same way as NO2, since traffic is a major source to street concentrations. In the current model setup the contribution of wood stoves are not modelled as detailed as traffic. The contribution from wood stoves is modelled on a 1x1 km2 resolution and thus has low spatial resolution in comparison with traffic, and the level and geographic distribution of woodstove pollution is also uncertain due to lack of knowledge. There is no knowledge of where the individual stoves are and when and how much they are used, so the contribution of each stove to the air pollution cannot be determined in detail. Results from previous measurement campaigns in villages on Zealand show that in areas with moderate wood burning the contribution to total PM2.5 concentrations from wood smoke can be in the range of 4-5% of particle concentrations, and in areas with high activity around 14-18% of total PM2.5 concentrations.

The highest PM2.5 and PM10 concentrations are about 17 µg/m3 and 22 µg/m3 in 2012, respectively, and are modelled at Jernbanegade in Roskilde. The levels are under the limit value of 25 µg/m3 for PM2.5 and 40 µg/m3 for PM10. Therefore, no exceedences are modelled for particles in the Municipality of Roskilde. The urban background level is relatively high, and the contribution of street traffic adds relatively few micrograms. For PM2.5 it is up to about 5 µg/m3 and for PM10 up to about 8 µg/m3. The contribution is larger for PM10 as coarser particles are also included, for example non-exhaust from traffic in the form of road, tire and brake wear and re-suspension of this.

There are about 31,100 addresses in the Municipality of Roskilde. 90% of all addresses have NO2 street concentration levels below 14 µg/m3, while 10% have levels more than 14 µg/m3. Only 1.3% of all addresses have levels above 20 µg/m3, and 0.25% above 30 µg/m3. The distribution of PM2.5 and PM10 street concentrations is dominated by the regional contribution, which is large, and the contribution from local sources is less than for NO2. 90% of all addresses are close to the regional background contribution for PM2.5 and PM10.

Results of the emission inventory for all sources

Total emissions for nine substances are presented and further broken down by source type for NOx and PM2.5. The emission inventory for the Municipality of Roskilde shows that the largest source to NOx is road traffic, followed by other mobile sources (industry, agriculture, railway, etc.) and energy production. The major source of PM2.5 is wood stoves and boilers, followed by road transport and other mobile sources (industrial, agricultural, railway, etc.). Other sources contribute marginally.

The geographic variation in emissions in the Municipality of Roskilde is examined for selected substances which vary geographically differently since they have different sources. The following substances were selected. NOx was chosen as an indicator for traffic. It varies largely as CO (carbon monoxide). NMVOC (non-methane volatile hydrocarbons) was selected as an indicator of combustion but also solvents, products, industry, traffic, etc. PM2.5 was picked as an indicator for particulate matter with multiple sources such as wood stoves, traffic, industry, etc. PM2.5 varies geographically almost as PM10 and TSP (suspended particulate matter). SO2 (sulphur dioxide) is an indicator for the combustion of fuels containing sulphur. CH4 (methane) is selected as an indicator of agricultural, and sewage and waste management, and NH3 (ammonia) represents agricultural emissions.

Results of the emission inventory for road traffic

It has not been possible within the framework of this project to carry out a detailed emission inventory of traffic on roads in the Municipality of Roskilde. Therefore, results from other emission inventories from Copenhagen have been used to clarify the emission distribution by vehicle category, Euro emission classes and fuel types.

The vehicle distribution at H. C. Andersens Boulevard in Copenhagen has about 76.4% passenger cars, 7.5% taxis, 11.4% vans and 4.7% heavy-duty vehicles (buses and trucks). Passenger cars contribute about 40% of NOx emissions, taxis 4%, vans 18% and heavy vehicles 38%. Considering heavy-duty vehicles, trucks contribute about 24% of the total emissions, and buses 14%. The contribution from the heavy-duty traffic is supposed to be higher in the Municipality of Roskilde as there is no Low Emission Zone in the Municipality of Roskilde. The Low Emission Zone in Copenhagen reduces emissions from buses and trucks. The contribution from taxis is expected to be less in Municipality of Roskilde due to less taxies.

The distribution for particle emissions according to vehicle type is broadly as for NOx although not quite the same. Overall for PM2.5 emissions from traffic, particle exhaust contributes about 40% and non-exhaust about 60%. For PM10 the corresponding numbers are 17% and 83%, respectively, as the proportion of non-exhaust is larger for PM10 compared to PM2.5.

NOx emission factors (emissions per vehicle km) are presented for individual vehicle categories which show that NOx emissions are about 10 times as high per km for heavy-duty vehicles compared to passenger cars and taxis. Vans have about 3 times higher emission factors as passenger cars and taxis. NOx emission factors for heavy-duty traffic are likely to be even higher in the Municipality of Roskilde as there is no Low Emission Zone.

All in all, 84% of NOx emissions are estimated to derive from diesel vehicles in 2015 and the rest from petrol cars.

The oldest cars contribute the most emissions per vehicle. As an example, about 29% of NOx emissions are from older vehicles less or equal to the Euro 3 emission standard. For passenger cars, trucks and buses this include vehicles registered from 2001 and vans from 2002, e.g. vehicles that are about 14 - 15 years old or older in 2015.

Results for health impact assessment due to air pollution

The number of premature deaths in 2010 is presented as an indicator of all the health effects that are part of the EVA system since premature deaths constitute a significant portion of the associated external costs.

The number of premature deaths in the Municipality of Roskilde is estimated to about 64 in 2010 which equals around 680 life years lost in 2010. This is due to all air pollution in the Municipality of Roskilde caused by all Danish emissions and emissions from abroad. The geographic distribution of premature deaths shows, as expected, that there are most premature deaths in urban areas, where the population density is greatest e.g. in Roskilde. In comparison all air pollution in Denmark causes about 3,300 premature deaths in 2011.

Calculations for Copenhagen shows that local emission sources in the Municipality of Copenhagen and the Municipality of Frederiksberg contribute about 12% of all premature deaths in the two municipalities. For Municipality of Roskilde it is expected to contribute even less. On the other hand, more than 88% of premature deaths in the Municipality of Roskilde are due to other emissions in Denmark and abroad.

Results for external costs due to health effects of air pollution

The external costs related to the health effects of all air pollution in the Municipality of Roskilde is estimated to be about DKK 500 million in 2010. It is a result of emissions in the Municipality of Roskilde, other Danish emissions and emissions from abroad. In comparison the external costs of all air pollution in Denmark is estimated to about DKK 28 billion in 2011.

Calculations for Copenhagen show that local emissions in the Municipality of Copenhagen and the Municipality of Frederiksberg contribute about 11% of the total external costs. This means that about 89% of all external costs related to air pollution in Copenhagen are caused by emissions outside Copenhagen. It is probably even more pronounced for the Municipality of Roskilde.

The geographical distribution of the externals costs mirrors the distribution of premature deaths.