Ellermann, T., Nordstrøm, C., Brandt, J., Christensen, J., Ketzel, M. & Jensen, S.S. 2011: The Danish Air Quality Monitoring Programme. Annual Summary for 2010. National Environmental Research Institute, Aarhus University. 55 pp. -NERI Technical Report No. 836. http://www.dmu.dk/Pub/FR836.pdf

 

Summary and Conclusion

This report presents the result of the Danish Air Quality Monitoring Programme in 2010. The monitoring programme is carried out by the National Environmental Research Institute (NERI) at University of Aarhus. The programme is based on continuous measurements at nine monitoring stations situated in the four largest cities and two stations in background areas. These measurements are supplemented with model calculations using NERI’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 (NO_x/NO₂), particulate mass (PM₁₀ and PM_2.5), particle number, benzene (C₆H₆), toluene (C₇H₈), carbon monoxide (CO), ozone (O₃), lead (Pb), arsenic (As), cadmium (Cd), mercury (Hg), nickel (Ni), and polycyclic aromatic hydrocarbons (PAH). In 2009 the programme was expanded with measurements of a number of volatile organic compounds (VOC’s) that are precursors for formation of ozone. 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 program serves as basis 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.

Due to the revision of the monitoring program there is a number of changes in the monitoring program and in this years report. The main changes are the following:

• The two Danish monitoring programs (the Background monitoring programme aimed at assessing the atmospheric depositions to nature and the Air quality monitoring program measurements related to human health) has been integrated into one program with two annual reports. The first one with focus on air quality and human health and the second one with focus on air quality and environment. The material previously presented in this report on air quality and vegetation has therefore been moved to the second report.
• The rural monitoring station at Lille Valby was moved about two km west in June 2010 and is now situated at Risø close to NERI.
• Activities concerning measurements of heavy metals have been reduced because the concentrations are low compared to limit values. Moreover, a new analysis technique has been used for analysis of heavy metals. It has therefore only been possible to analyse for those five heavy metals that are included in the EU directives. However, it is expected that more metals will be included during 2011.
• As a new thing this report presents results from analysis of sodium. This is in order to be able to correct PM₁₀ for the content of salt from sea and winter salting of roads.
• Finally, the report presents results from measurements of number of particles in Copenhagen. 

PM₁₀ were at all the stations below both the annual limit value (40 µg/m³) and the limit value for the 35^th highest daily average value for PM₁₀ (50 µg/m³). PM_2.5 was lower than the annual limit value (25 µg/m³) valid from 2015. The number of particles in ambient air were about 16000 particles per cm³ at the street station H.C. Andersens Boulevard. This is considerably higher than in urban and rural background. A significant reduction in particle number has been observed since 2002.

The sodium content in PM₁₀ on street stations were about 1 µg/m³ corresponding to en estimated annual salt content (NaCl) of about 2.6 µg/m³. High diurnal values of salt above 10 µg/m³ was observed during periods with salting of roads.

The annual limit value for NO₂ (40 µg/m³ in 2010) was exceeded at one street station in Copenhagen (H.C. Andersens Boulevard), whereas no exceedances were observed in Odense, Aalborg and Aarhus. The NO₂ concentrations generally decreased in 2010. However, at one station in Copenhagen (1103) an increase was observed. This is believed to be a temporary effect due to ongoing local construction work at two nearby sites.

Model calculations at selected streets in Copenhagen and Aalborg indicate that the limit value was exceeded at several streets in Copenhagen but not in Aalborg in 2010. In general modelling confirmed that the street station at H.C. Andersens Boulevard (1103) in Copenhagen represents one of the most polluted streets in Copenhagen, whereas the traffic station in Aalborg (6153) represents the average level for the 31 selected streets in Aalborg. Due to new traffic information Sydhavnsgade in Copenhagen has now significant higher NO₂ concentration as now by far the most polluted street of the 138 selected streets in Copenhagen. The model calculations show a tendency for high concentrations on streets with housing on one side of the street and open space on the other side. NERI will in 2011 participate in a project with Danish EPA with supplementary measurements in order to examine some of the hot spot situations in Copenhagen further.

The ozone levels were in 2010 almost the same as in 2009 at all rural and urban background stations and no clear trend was thus observed. The information threshold at 180 µg/m³ was exceeded once. The target value for the max 8 hours ozone concentration on 120 µg/m³ was not exceeded, but the long-term objective for this target was exceeded at all non-traffic stations.

The report presents results for volatile organic compounds (VOC) measured at the urban background in Copenhagen. VOC’s can act as ozone precursors, although the formation of ozone in Denmark is in general small due to moderate solar radiation. The ozone pollution in Denmark is to a large extent caused by 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 decade.

Measurements of particle bound PAH concentrations were performed at H.C. Andersens Boulevard, Copenhagen. The average concentration of benzo[a]pyrene was 0.34 ng/m³. The target value for benzo[a] pyrene (1 ng/m³) was not exceeded in 2010.

Actual data, annual and multi-annual summaries are available at the website of NERI (http://www.dmu.dk/International/Air).