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No. 281: The Danish Air Quality Monitoring Programme. Annual Summary for 2017

Ellermann, T., Nygaard, J., Nøjgaard, J.K., Nordstrøm, C., Brandt, J., Christensen, J., Ketzel, M., Massling, A., Bossi, R. & Jensen, S.S. 2018. The Danish Air Quality Monitoring Programme. Annual Summary for 2017. Aarhus University, DCE – Danish Centre for Environment and Energy, 83 pp. Scientific Report from DCE – Danish Centre for Environment and Energy No. 281. http://dce2.au.dk/pub/SR281.pdf

Summary

This report presents the result from the Danish Air Quality Monitoring Programme in 2017. The monitoring programme is carried out by the DCE - Danish Centre for Environment and Energy (DCE) at Aarhus University. The core part of this programme consists of continuous measurements at eleven monitoring stations; nine stations situated in the four largest cities, two stations located in background areas and a station in a suburban area. These measurements are supplemented with model calculations using DCE’s air quality models.

The aim of the program is to monitor air pollutants relevant to human health in accordance with the EU air quality directives. The programme includes measurements of sulphur dioxide (SO2), nitrogen oxides (NOx/NO2), particulate mass less than 10 (PM10) and 2.5 micrometers (PM2.5), particle number, benzene (C6H6), toluene (C7H8), carbon monoxide (CO), ozone (O3), polycyclic aromatic hydrocarbons (PAHs) and a number of heavy metals including lead (Pb), arsenic (As), cadmium (Cd), mercury (Hg), nickel (Ni), and a number of volatile organic compounds (VOCs) that are precursors for formation of O3. The measurements and model calculations are used to evaluate the Danish air quality in relation to limit values as well as to follow trends. Further, the obtained data are used for determination of sources of the air pollutants, basis for evaluation of the impact of regulations of emissions and as basis for various research projects related to air quality.

The permitted number of exceedances in a year of the diurnal limit value of 50 µg/m3 for PM10 was not exceeded at any station in the measuring network. Likewise, there were no exceedances of the annual limit values for PM10 (40 µg/m3) and PM2.5 (25 µg/m3). The average exposure indicator (AEI) determined as a running three-years average of the average urban background concentration of PM2,5 has decreased with about 30 % since 2010 and hence the target (15 % reduction) has been reached.

Due to technical difficulties with two new instruments, it has not been possible to measure the number of particles between 11 and 41 nm in 2017 and data for 2017 has to be regarded as preliminary. Therefore, the particle number represents the particle range from 41 to 559 nm. The particles in ambient air was about 5,000 particles per cm3 as an annual average at the street station H.C. Andersens Boulevard. This is roughly a factor of 2 higher than in suburban and 2.5 higher than in urban and rural background, respectively. A significant reduction of more than 40% in particle numbers has been observed since 2002. This reduction has mainly been attained by reduction of traffic emissions (cleaner fuel, particle filters etc.).

The annual limit value for NO2 (40 µg/m3) was not exceeded at any of the measurements stations in Denmark. Model calculations at selected streets in Copenhagen and Aalborg in 2017 indicate no exceedances of the limit values whereas model calculations of 98 streets in Copenhagen in 2016 indicated 6 exceedances.

The annual average O3 concentrations in 2017 were at the same level as in the previous years but the maximum 8-hours running mean concentration was smaller in 2017 compared to 2016. This change was due to differences in the meteorological conditions.  No clear trend is observed for the average O3 concentration. The information threshold of 180 µg/m3 was not exceeded at any of the measurement stations in 2017. The target value for the maximum daily 8-hours mean O3 concentration of 120 µg/m3 was not exceeded, but the long-term objective for this parameter was exceeded at all Danish stations. The target value entered into force in 2010 while the long-term objective has not entered into force and the data for this has not been decided yet.

Measurements of VOCs at the urban background in Copenhagen showed concentration levels between 0.03 µg/m3 and 0.827 µg/m3 for the selected 17 different compounds. VOCs can act as O3 precursors, and the aim of these measurements is to improve the general understanding of the O3 formation at a European level. The formation of O3 in Denmark is in general small due to moderate solar radiation. O3 pollution in Denmark is to a mainly the result of long-range transport of pollutants from other European countries south of Denmark.

The levels of SO2 and heavy metals have decreased for more than two decades and are now far below the limit values. The limit values for benzene and CO are not exceeded and the levels have decreased for the last decades.

Measurements of concentrations of particle bound PAH were performed at H.C. Andersens Boulevard, Copenhagen and at the suburban measurement station at Hvidovre. The average concentration of benzo[a]pyrene was 0.18 ng/m3 and 0.29 ng/m3 at H.C. Andersens Boulevard and Hvidovre, respectively. The target value for benzo[a]pyrene (1 ng/m3) was not exceeded in 2017.

Measurements of the chemical content in PM2.5 were due to minor revisions of the program only carried out at the rural background station at Risø. The results are almost unchanged compared to 2016.

Model calculations show that air pollution causes about 3,200 premature deaths in Denmark as average for 2014-2017 and a large number of other negative health effects. There is about 400 fewer premature deaths in 2017 compared to 2016. This decrease is due to a general reduction in emissions and extraordinary low peak O3 concentrations in 2017 due to the weather conditions during summer 2017. About 770 (24 %) of the premature deaths are due to Danish emission sources while the remaining premature deaths are caused mostly by European sources outside Denmark. The total health related external costs for Denmark have been calculated to 3.3 billion EUR (~25 billion DKK) as an average over the three years 2014-2017. The negative health effects and external costs have declined with about 40% since 1988-1990. The calculation of the health impacts and external costs are associated with considerably uncertainties among others because the model underestimates the concentrations of airborne particles compared to the measurements. Moreover, newer results indicate that there is an independent health impact due to nitrogen oxides and this impact has not been included in the model yet.

Actual data, annual and multi-annual summaries are available at the website of DCE (http://dce.au.dk/en/authorities/air/), in Danish (http://dce.au.dk/myndigheder/luft/).