Aarhus University Seal / Aarhus Universitets segl

No. 234: The Danish Air Quality Monitoring Programme. Annual Summary for 2016

Ellermann, T., Nygaard, J., Nøjgaard, J.K., Nordstrøm, C., Brandt, J., Christensen, J., Ketzel, M., Massling, A., Bossi, R. & Jensen, S.S. 2017. The Danish Air Quality Monitoring Programme. Annual Summary for 2016. Aarhus University, DCE – Danish Centre for Environment and Energy, 78 pp. Scientific Report from DCE – Danish Centre for Environment and Energy No. 234. http://dce2.au.dk/pub/SR234.pdf

Summary

This report presents the result from the Danish Air Quality Monitoring Programme in 2016. 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 ozone (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) has de-creased with about 20 % since 2010 and hence the target (15 % reduction) has been reached.

The number of particles in ambient air was about 13,000 particles per cm3 as annual average at the street station H.C. Andersens Boulevard. This is roughly a factor of 3.5 higher than in suburban and 4.5 higher than in urban and rural background, respectively. A significant reduction in particle number has been observed since 2002. This reduction has mainly been reached by reduction of traffic emissions (cleaner fuel, particle filters etc.). 

The annual limit value for NO2 (40 µg/m3) was exceeded at one street station in Copenhagen (H.C. Andersens Boulevard), whereas no exceedances were observed in Odense, Aalborg and Aarhus. At H.C. Andersens Boulevard (HCAB/1103) there were still elevated concentrations of NO2 compared to the situation before 2010 due to a permanent change in the traffic lanes at the street segment in front of the measurement station. Additionally, there has been a gradually decrease in the concentrations during the last years in parallel to the decrease observed at Jagtvej. In October 2016, the position of the measurement station was adjusted to the previous distance to the road lanes and a subsequent drop in concentrations were observed. 

Model calculations at selected streets in Copenhagen and Aalborg indicate that the limit value was exceeded at 6 out of 98 calculated streets in Copenhagen but not at any streets in Aalborg in 2016. The number of street segments with model calculated exceedances in Copenhagen has now decreased to about one third compared to 2010.

The O3 levels in 2016 were at the same level as in the previous years. No clear trend is observed for the average O3 concentration. The information threshold of 180 µg/m3 was exceeded in 2016 at the Risø station and the public was in-formed through the Danish Environmental Protection Agent. 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. 

Measurements of VOCs at the urban background in Copenhagen showed con-centration levels between 0.01 µg/m3 and 0.82 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 large extent the result of long distance 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 0.21 ng/m3 and 0.23 ng/m3 at H.C. Andersens Boulevard and Hvidovre, respectively. The target value for benzo[a]pyrene (1 ng/m3) was not exceeded in 2015.

Measurements of the chemical content in PM2.5 showed that the annual aver-age concentrations of ammonium (NH4+), sodium (Na+), potassium (K+), magnesium (Mg2+), chloride (Cl-), nitrate (NO3-) and sulfate (SO42-) are very similar at the street station at H.C. Andersens Boulevard and at the rural station at Risø. The main difference between the two stations is found for elemental car-bon (EC), organic matter (OM) and calcium (Ca2+) where the concentrations are higher at the street station compared to the rural background station. This is mainly due to emissions of these compounds from the traffic in Copenhagen.

Model calculations shows that air pollution causes about 3,600 premature deaths in Denmark as average for 2014-2016 and a large number of other negative health effects. About 850 (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 3.9 billion EUR (~29 billion DKK) as an average over the three years 2014-2016. The negative health effects and external costs have declined with about 40% since 1988-1990.

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/).