1. MAIN MESSAGES ON OZONE TRENDS
Dick Derwent
rdscientific, Newbury, United Kingdom
16th TFMM Meeting, Crakow, Poland
8th May 2015

2. Much more needs to be done
European Environment Agency

3. UNDERSTANDING EUROPEAN OZONE TRENDS
European ozone has two main components
Hemispheric scale baseline ozone
European regional scale ozone
WE NEED TO UNDERSTAND THE TRENDS IN BOTH COMPONENTS

4. ACKNOWLEDGEMENTS – BASELINE OZONE TRENDS
D. Parrish
K. Law
J. Staehelin
O. Cooper
H. Tanimoto
Volz-Thomas
S. Glige
H.-E. Scheel
M. Steinbrecher
E. Chan
Atmos. Chem. Phys. 12, 1-20, (2012)

5. LONG-TERM OZONE TRENDS - 1957-ONWARDS
DE0009R Zingst

6. LONG-TERM OZONE TRENDS – 1980s ONWARDS
DE0057G

7. AIR MASS ORIGINS AT MACE HEAD, IRELAND – EMEP SITE IE0031R
Baseline air masses

8. LONG-TERM OZONE TRENDS – 1990s ONWARDS
Baseline ozone has increased, levelled out and started to decline
IE0031R

9. LONG-TERM OZONE TRENDS – 1990s ONWARDS MACE HEAD, IRELAND
Data courtesy of Peter Simmonds

10. BASELINE OZONE - SUMMARY
Baseline ozone has:
increased
levelled off
started to decrease
Why is this ? Because of intercontinental transport.
Intercontinental attribution can be provided for all EMEP sites.
Atmos Environ 112,

11. INTERCONTINENTAL SOURCE ATTRIBUTION FOR OZONE FORMATION AT MACE HEAD, IRELAND
IE0031R
Tagged ozone labelling

12. LONG-TERM OZONE TRENDS – 1990s ONWARDS
Mace Head, Ireland
Summertime elevations have been reduced

13. REGIONAL OZONE TRENDS
Health effects assessment based on World Health Organisation 2005 guidelines
Daily maximum 8-hour ozone mean concentrations below 50 ppb
Acknowledgements
Anne-Gunn Hjellbrekke CCC for reformulating EMEP ozone database using annual maximum 8-hour means
Handbook on Environmental Chemistry 132 (2012)

14. TRENDS IN MAXIMUM 8-HOUR MEAN FOR 1980 - 2009
most important period because it covers the entire period over which trends are expected
5 sites meet tight data capture criteria
DE0003R Schauinsland
DE0002R Langenbrugge
DE0001R Westerland
GB0039R Sibton ± 0.9 ppb per year
GB0036R Harwell -1.2 ± 0.7 ppb per year

15. MAXIMUM 8-HOUR MEAN OZONE TRENDS – GB0039R
Sibton
-1.4 ± 0.9 ppb per year

16. MAXIMUM 8-HOUR MEAN OZONE TRENDS – GB0036R
Harwell
-1.2 ± 0.7 ppb per year

17. TRENDS IN MAXIMUM 8-HOUR MEAN FOR 1990 - 2009
40 stations have complete records over this period
16 stations show highly significant downwards trends α < 0.1
19 stations show significant downwards trends α > 0.1
5 stations showed no trends

18. MAXIMUM 8-HOUR MEAN OZONE TRENDS – NL0009R
Kollumerwaard
-0.9 ± 0.7 ppb per year

19. MAXIMUM 8-HOUR MEAN OZONE TRENDS – IT0004R
Ispra
-2.3 ± 1.1 ppb per year

20. GB0038R Highest 8-hour running mean in ppb at Lullington Heath
-1.7 ± 1.1 ppb per year

21. DOWNWARDS TRENDS AT LONG-RUNNING RURAL MONITORING STATIONS BETWEEN 1990 AND 2010
WHO AQG

22. WHY SHOULD DOWNWARDS TRENDS BE STRONGEST FOR STATIONS WITH HIGHEST OZONE IN 1990s ?
It is likely that downwards trends at stations with highest ozone levels have been driven by European regional pollution emission reductions
it is likely that the trends due to European regional pollution emission reductions at stations with lowest ozone levels have been offset by another trend
what is the offsetting trend at the stations with lowest ozone levels ?
presumably the growth in hemispheric baseline levels is the offsetting trend

23. INTERCONTINENTAL SOURCE ATTRIBUTION FOR OZONE FORMATION AT MACE HEAD, IRELAND
IE0031R
Tagged ozone labelling
European regional pollution event

24. SUMMARY OF EUROPEAN REGIONAL OZONE TRENDS
Health effects assessment based on maximum 8-hour mean ozone concentrations
episodic peak levels have declined significantly since EMEP measurements began at long-running stations
downwards trends have been greatest at stations where ozone levels are highest
downwards trends driven by controls on VOC and NOx emissions
downwards trends at lowest ozone sites have been offset by increasing hemispheric ozone baselines
hemispheric baseline ozone has started to decrease and this will pull down ozone across all sites in 2010s

25. KEY MESSAGES
1980s – formulate CLRTAP VOC and NOx protocols
Parties based aspirations on motor vehicle controls
1990s – EU implement motor vehicle emission directives
s – see decline in peak 8-hour mean ozone levels
s – see decline in observed VOCs and NOx
s – direct relationship between precursor emission reductions and decline in episodic peak ozone