Aarhus University Seal / Aarhus Universitets segl

No. 360: The Danish Air Quality Monitoring Programme. Annual Summary for 2018

Ellermann, T., Nygaard, J., Nøjgaard, J.K., Nordstrøm, C., Brandt, J., Christensen, J., Ketzel, M., Massling, A., Bossi, R., Frohn, L.M., Geels, C. & Jensen, S.S. 2020. The Danish Air Quality Monitoring Programme. Annual Summary for 2018. Aarhus University, DCE– Danish Centre for Environment and Energy, 83 pp. Scientific Report No. 360. http://dce2.au.dk/pub/SR360.pdf

Summary

This report presents the result from the Danish Air Quality Monitoring Programme in 2018. The monitoring programme is carried out by the Danish Centre for Environment and Energy (DCE) at Aarhus University. The core part of this program consists of continuous measurements at thirteen monitoring stations. Eight of these stations are located in the four largest cities, four stations are located in background areas and one station is located 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), mass of particles with diameters less than 10 and 2.5 micrometers respectively (PM10 and 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 applied for evaluating the Danish air quality in relation to limit values as well as to follow trends. Furthermore, the obtained data are used for determination of sources of the air pollutants, as 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) deter-mined as a running three-years average of the average urban background con-centration 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 2017-2018. Therefore, the particle number represents the particle range from 41 to 478/559 nm (dependent on instrument version but the difference is negletable). The particle number in ambient air was about 4,000 particles per cm3 as an annual average at the street station H.C. Andersens Boulevard. This is roughly a factor of two higher than in suburban areas and in urban and rural background. Since 2002, significant reduction of more than 40 % in particle numbers has been observed. This reduction has mainly been attained by reduction of traffic emissions (cleaner fuel, particle filters etc.). 

The limit values for NO2 was not exceeded at any of the monitoring stations in Denmark. Model calculations at selected streets in Copenhagen and Aalborg in 2018 showed that the annual average concentration at one single street segment in Copenhagen were slightly above the limit value (40 µg/m3).  

The annual average O3 concentrations in 2018 were at the same level as in the previous years but the maximum 8-hours running mean concentration was higher in 2018 compared to 2017. 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 2018. 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 date for this has not yet been decided. 

Measurements of VOCs at the urban background in Copenhagen showed con-centration levels between 0.01 µg/m3 and 0.91 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 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 been decreasing 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 0.25 ng/m3 and 0.28 ng/m3 at H. C. Andersens Boulevard and Hvidovre, respectively. The target value for benzo[a]pyrene (1 ng/m3) was not exceeded in 2018.

Due to minor revisions of the program measurements of the chemical content in PM2.5 were only carried out at the rural background station at Risø. The concentrations were slightly higher in 2018 compared to 2017 as a consequences of the low precipitation in 2018. Low precipitation gives higher particulate concentrations. 

Model calculations show that air pollution causes about 4,200 premature deaths in Denmark as average for 2016-2018 and a large number of other negative health effects. This is about 1,000 premature deaths more compared to the reporting for 2017. These higher numbers are due to a major update of the model systems and not due to an increase in the air pollution. About 1,220 (29 %) of the premature deaths are due to Danish emission sources while the remaining premature deaths are caused mostly by sources outside Denmark. The total health related external costs for Denmark have been calculated to 79 billion DKK as an average over the three years 2016-2018. This is more than a doubling of the external costs compared to the previous reporting. This higher number is mainly due to an increase in the economic value of a statistic life. The negative health effects and external costs have declined with about 38 % since 1988-1990. It should be noted that the calculation of health impacts and external costs are constrained with considerably uncertainties. 

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/).