Chemistry Reference
In-Depth Information
Air Pollution by Ozone Across Europe
Richard G. Derwent and Anne-Gunn Hjellbrekke
Abstract Episodic peak ozone levels in rural areas have been declining during the
last three decades due to regional pollution emission controls applied to the VOC
and NO
x
emissions from petrol-engined motor vehicles. Long-term downwards
trends have been observed at many long-running rural monitoring stations in
the EMEP ozone monitoring network. Downwards trends appear to be more
pronounced at those stations where initial episodic peak levels were highest and
insignificant at those stations where initial levels were lowest. This behaviour has
been interpreted as resulting from the combined effect of regional pollution controls
and increasing hemispheric ozone levels. Hemispheric ozone levels have been
steadily rising in the northern hemisphere because of growing man-made emissions
of tropospheric ozone precursors. Episodic ozone levels in major European towns
and cities are rising towards the levels found in the rural areas surrounding them, as
exhaust gas catalysts fitted to petrol-engined motor vehicles reduce the scavenging
of ozone by chemical reaction with emitted nitric oxide.
Keywords Hemispheric background, Long-term trends, NO
x
and VOCs, Ozone,
Photochemical ozone formation, Regional pollution controls
Contents
1 Introduction to Ozone Air Quality Across Europe . . . ....................................... 56
2 Spatial Distribution of Episodic Peak Ozone Levels Across Europe . . . . . . . . . . . . . . . . . . . . . . 58
3 Trends in Episodic Peak Ozone Levels Across Europe over the 1980-2009 Period . . .... 63
