4.2.3 Tropospheric Ozone 

The Tropospheric Ozone problem is to a great extent related to the Urban Environment issue, because the main causes for tropospheric ozone occurrence are ozone precursors (NOx, CO and non-metallic volatile organic compounds - NMVOC), which are related to the air pollution from motor vehicles and industry. However, this problem is connected with changes in the atmosphere, and therefore included in this chapter as a subsection of the Atmosphere issue. A detailed table of all measured and proposed indicators under this issue in national SoE reports, as well as those used in the Dobris+3 report (EEA 1998b) can be found in the Appendix (Table A-5). The GEO-2 does not deal with this problem in the chapter on SoE in Europe and Central Asia (UNEP 1999); the OECD did not propose indicators for it in its Core set, except VOC emission, included under the Urban Environment issue (OECD 1993).

	Pressure	State
	Total CO and NMVOC emissions	Ground level ozone concentration
Dobris+3	&	&
GEO-2
OECD 1993		&

Legend:
 

:	Indicators present in the SoE reports on the Internet
&	Indicators presented in the Dobris+3, GEO-2, and the OECD Core Set, or reported as measured in CEE countries, but not present on the Internet
	Indicators not reported as measured in CEE countries, and not covered in the Dobris+3, GEO-2, and OECD Core Set

Table 8 shows that emissions of ozone precursors (CO and NMVOC) have been measured in the majority of CEE countries. This is a pressure indicator; greater quantities of precursors emitted mean more tropospheric ozone generated. The next figure (14) is an example of graphical presentation. 

Ground-level ozone concentration is a state indicator which shows the quantities of tropospheric ozone present. Unfortunately, it has been measured in only 3 CEE countries (see Table 8). 

Response indicators have not been included in Table 8, because national and international legislative instruments, mentioned in the Dobris+3 (EEA 1998b) as response indicators, have been included in this chapter under the Socio-Economic Developments issue (see section 4.1 and Table 5). In addition, in the Czech Republic, Estonia, and Lithuania, the number of cars with catalytic converters has been reported as a response indicator, which is related to more environmental problems and has been referred to in subsection 4.2.2.

This section presented three main problems related to the Atmosphere issue: Climate Change, Acidification, and Tropospheric Ozone. Relationships between them, and some common indicators which can be used for all three problems were also pointed out. Generally, it is possible to conclude that the Atmosphere issue has been regarded as important in all electronic SoE reports, except the Albanian one. Again, the importance of the Socio-Economic Developments as the main driving force of pressures and response should be stressed. 

The next section deals with land, which receives impacts from the atmosphere, and causes pressures on waters, forests, and human society.