Abstract

Within the frame of the cooperation between the air quality monitoring networks of RIVM, GGD Amsterdam and DCMR Environmental Protection Agency comparative measurements are performed between RIVM and both regional networks at locations in Amsterdam (RIVM-GGD) and Rotterdam (RIVM-DCMR):
- Rotterdam: nitrogen dioxide and PM10 at location Bentinckplein/Statenweg.
- Amsterdam: nitrogen dioxide, PM10 and ozone at location Overtoom/Vondelpark.

The purpose of these comparisons is to demonstrate comparability of results obtained by the different networks. In case of sufficient comparability, mutual use can be made of their results.
All three networks use European reference methods for nitrogen dioxide, PM10 and ozone.

The evaluation involves comparison of hourly average results for nitrogen dioxide and ozone, and of daily average results for PM10 by applying orthogonal regression analysis and by examination of differences between results as a function of measurement period and concentration level.

Evaluation of the comparisons between RIVM and DCMR for the year 2013 shows that good correlations are found between the measurement results of both networks. In addition, differences between average results are small:
-for nitrogen dioxide results averaged over the whole year agree to within 2%
-for PM10 results agree to within 1,7%.

The relationships - expressed as linear functions - are in close agreement with those obtained for the year 2012.

Evaluation of the comparisons between RIVM and GGD for the year 2013 shows that good correlations are found between the measurement results of both networks. For ozone the correlation is excellent. For nitrogen dioxide and ozone the differences between the average results are small. For nitrogen dioxide the relationship between the results is in close agreement with that for 2012.

For PM10 only 54 data pairs are available for comparison. These result from four 2-week measurement periods. Although the average results agree to within 4%, the relationship between the data is "skewed": GGD Amsterdam apparently measures higher at higher concentration levels. However, no firm conclusion is possible because of the limited number of data available for evaluation.

Evaluation further shows that measurement uncertainties calculated in accordance with EN ISO 20988 are well within the criteria given in EU Directive 2008/50/EC in all cases.

As all networks have an EN ISO 17025 accreditation for the measurements it may be assumed that the quality levels and, consequently, the comparability of the results determined in these comparisons are representative for the networks as a whole.
Consequently, it should be possible for networks to make mutual use of results for the components compared (nitrogen dioxide and PM10 for all three; ozone for RIVM and GGD).