- The recent EEA report on national emission compliance.
A recent report from the European Environmental Agency (EEA) made some splash in the media, as it showed that many countries (among them Luxembourg) are missing their NOx emission limits.Here the relevant table:
The red crosses represent exceedance, the ticks conformance. What exceedance means is not very clear: probably it represents somewhere in the country an overshoot of the 8 hour limit of NOx concentration; the place where this happens will almost certainly be a heavy traffic urban road, but not a general mean annual concentration above the 40 ug/m3 limit (for NO2).
If we take the most important industrial countries (Belgium, France, Germany, Italy and the UK), all except Italy and the UK do not conform to the targets. It is an irony that the “über-grün” Germany overshoots all relevant pollutants as NOx, NMVOC (non-methane volatile organics, like terpenes); that Italy and the UK are in conformance might be real (I have some doubts, thinking of Roma or Neapoli traffic conditions), or simply a sign of a particular clever reporting. Emissions in NH3 (ammoniac) are clearly related to agriculture (especially cattle and swine rising), which explains that Denmark and the Netherlands are here big “sinners”.
Locally NOx/NO2 exceedance may give a wrong picture, so let us look at the yearly mean concentrations, as given by several EEA publications and databases.
2. The yearly average NO2 concentration in Luxembourg and other EU states.
The following picture shows the average annual concentration in the 6 validated Luxembourg measurement stations in 2011:
Vianden, Beidweiler and Beckerich are rural , Esch-Alzette and Luxembourg urban stations. It is only at the two Luxembourg (-City) stations that the EU target of 40 ug/m3 is exceeded. Not surprisingly, as the measurement stations lie at roads with very heavy traffic; the Esch-Alzette station is on a small hill (Galgenberg) with plenty of green vegetation around.
The following two pictures show the daily mean NO2 concentrations of Viandem and Luxembourg-Bonnevoie for 2015 (note the different vertical scales!) ( link)
Rural Vianden concentrations are very low, and even the heating months do not exceed 30 ug/m3; the situation in urban Luxembourg-Bonnevoie is quite different. The (relative) difference between the heating months situation and the summer months is much lower, and days exceeding the 40 ug/m3 limit are quite frequent. The lower summer concentrations at both sides are in my opinion mostly caused by an increased atmospheric mixing due to convective air transport.
Lets close this chapter with a picture showing the situation in 2012 for all EU member states:
The dots represent the median, the boxes delimit the 25 to 75 percentiles, and the whiskers ( the thin vertical lines) show the region containing 99% of the values.
Clearly Luxembourg fares very well: if we take the median concentration, we see that 19 countries surpass Luxembourg, which has the 9th “best” attainment of the 28 EU countries. If we look at the upper whisker end only 3 or 4 countries have lower or similar upper bounds.
Conclusion: Luxembourg is NOT the bad guy!
3. Hourly NO2 concentrations
I will close this first part with a look at the hourly NO2 concentrations during the last 7 days; we will compare the measurements made at Vianden, Luxembourg-Bonnevoie and Diekirch (meteoLCD):
At Vianden we see a daily maximum which mostly does not exceed 3 times the daily minimum (except the last day); the urban Luxembourg-Bonnevoie data show two daily spikes, one in the morning and one in the afternoon: clearly a sign of increased traffic during the rush hours where commuters come in or leave the town. The range extends from 10 to 80 ug/m3, a factor of 8.
The NO2 sensor in Diekirch has a positive bias of about 10 ug/m3, so take the left blue scale for reading.Here we have a very pronounced peak in the morning (commuter traffic and normally a time of morning inversion); the afternoon peak is muted or absent. The range extends from 10 to 100 ug/m3, a factor of 10, similar to the Luxbg-Bonnevoie situation. The red curve shows the NO readings, which are always lower than the NO2. NOx concentration corresponds to the sum of the blue and red curves.
Comparing the last two curves, we observe a flattening during the last two days (11 and 12 June): you will guess that these are the weekend days with no commuter rush hour!
In the 2nd part of this blog (coming asap), I will analyze emissions by different types of cars, using data from a truly excellent DEFRA report from 2011.