1. Introduction + 2. Availability of data

EUROPEAN TOPIC CENTRE ON AIR QUALITY

RIVM NILU NOA DNMI

Topic Report no. 03/1999 Part II - European Topic Centre on Air Quality

Overview of the situation in the European Union

during the 1998 summer season (April-August)

Report to the Commission by the European Environment Agency

By

Rob Sluyter, Tim de Paus

November 1998

Download the report part II as PDF File (Approx. 4367 Kb)

Ozone is a strong photochemical oxidant, which may cause serious health problems and damage to materials and ecosystems. Human exposure to elevated levels of ozone concentrations can give rise to decreases in lung function and inflammatory responses. Symptoms observed are cough, chest pain, difficulty in breathing, headache and eye irritation.

Both laboratory and epidemiological data indicate large variations between individuals in response to episodic O₃ exposure, the effects seem to be more pronounced in children than in adults [WHO, 1995]. Studies indicate that exposure to ozone concentrations in the range 160-360 for a period of 1-8 hours reduces various pulmonary functions.

In view of the harmful effects of photochemical pollution, the Council adopted in 1992 Directive 92/72/EEC on air pollution by ozone. The Directive defined threshold values, established procedures for harmonised monitoring, for collecting and exchanging data and for information of the public when exceedances of threshold values occur.

More information on the current experience and knowledge concerning photochemical air pollution may be found in "Tropospheric Ozone in the European Union, The Consolidated Report" [Beck et al., 1998] which has been prepared following Article 8 of the Directive.

The thresholds set by the Directive are presented in Table 1. As far as data reporting is concerned, two types of reporting can be distinguished according to Article 6 of the Directive:

1. Exceedances of the population information and warning thresholds (date, time, duration and maximum concentration) must be reported to the Commission within one month after occurrence (data is not necessarily validated);
2. Exceedances of all threshold values including some additional statistics (percentiles, maxima) must be provided within 6 months after the end of a calendar year (validated data).
   

Table 1. Threshold values for ozone concentrations set in Directive 92/72/EEC

According to Article 7 of the Directive, the Commission prepares a report summarising all the information transmitted by the Member States at least once a year. The report for the 1997 calendar year will become available together with this document [De Leeuw and De Paus, 1998].

In this document a first assessment is made of the 1998 summer season, based only on the exceedances of the population information and warning thresholds for ozone, which were transmitted by the Member States after the end of each month.

The report is mainly intended to provide fast feedback to the Member States on their data. It also enables the Member States to compare the levels observed in the past summer season with those observed in other Member States. Note that information presented in this document is not necessarily based on validated monitoring data and hence should be considered preliminary.

2. Availability of data

According to the Directive, exceedances of the population information and warning thresholds are to be transmitted to the Commission within one month following the observation.

This year, for the first time, all 15 EU Member States provided information on the observed exceedances in time (the deadline for transmitting data was set at 20 September 1998), or indicated that no exceedances were observed. It is greatly appreciated by the Commission that MS were able to transmit August exceedance data before the formal deadline as set in the Directive.

Some countries submitted files which were not formatted according to the prescribed Commission requirements [Council Directive 92/72/EEC on Air Pollution by Ozone. Information and data exchange formats. Doc.Rev. 11/243/95]. These files by exception were converted at the European Topic Centre on Air Quality (ETC-AQ) for further processing.

As was the case in 1997, Ireland, Denmark, Finland and Sweden did not record any exceedance of the 180 µg/m³ threshold this year.

Table 2 presents an overview of observed exceedances per country per month.

Member States were requested to check and, if necessary, update the information on ozone monitoring sites implemented in the framework of the Directive made available to the Commission. For the interpretation of ozone data it is essential to have information on the direct surroundings of the station since the ozone concentration may be scavenged by locally emitted nitrogen oxides or by enhanced dry deposition which might occur for example under a forest canopy. Member States were requested to classify their stations as street, urban background¹, rural or industrial stations as a first description of the environment of the stations.

Table 2: Overview of observed exceedances per month per country in 1998. p: exceedance of the population information threshold reported, -: no exceedance reported, w: exceedance of the threshold for warning of the public reported.

	April	May	June	July	August
AT	p	p	p	p	p
BE	-	p	p	-	p
DE	-	p	p	p	P
DK	-	-	-	-	-
ES	p	p	p	p	p
FI	-	-	-	-	-
FR	p	p	p	p	w
GB	p	p	-	p	p
GR	p	p	p	w	p
IE	-	-	-	-	-
IT	p	p	p	p	p
LU	-	p	p	-	p
NL	-	p	p	p	p
PT	-	-	-	-	p
SE	-	-	-	-	-

Only a few countries transmitted information on their operational stations. For other countries, the 1997 station configuration has been used throughout this report, merged with the list of stations reporting exceedances during the past summer season.

Map 1 presents the location of all ozone monitoring stations (street and urban background taken together as 'urban') assumed to be operational during the 1998 summer season.

1066 ozone monitoring sites are assumed to be operational in the framework of the Directive. From these, 278 stations are situated in rural areas, 374 stations in urban background environments, 120 are street stations and 294 stations were characterised as industrial station or the monitoring environment was not specified. The number of stations is comparable to the number of stations operational in 1997.

Note that, as only exceedances of thresholds were reported, it is not clear whether stations were operational continuously. It is possible that ozone concentrations exceeded a threshold at a site but this was not reported because the monitoring station was temporarily out of operation.²

In this report exceedances are counted on a daily basis, that is, a day on which a threshold is exceeded at least once, is calculated as one exceedance day.

Map 1: Ozone monitoring stations implemented in the framework of Directive 92/72/EEC on air pollution by ozone, scheduled to be operational during 1997.

¹ Urban background: station located in the built-up area of the city but not directly influenced by emission sources such as traffic or industry.

²The annual report [De Leeuw and De Paus, 1998] gives information on the percentage of time stations were operational, most stations score >90%.

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