3. Summary of reported data for 1995

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Air pollution in the European Union - Exceedance of ozone threshold values in 1995 and summer 1996 - Part I

3. SUMMARY OF REPORTED DATA FOR 1995

The location of monitoring stations used for the implementation of the ozone directive and reporting during 1995 is presented in Map 1. In total information for 858 stations has been received. All Member States use the reference method (UV absorption) as prescribed in Annex V of the Ozone Directive, however, at a limited number of stations chemiluminescence is used.

A summary of the maximum concentration measured at any of the reporting stations when exceedance of a threshold value is observed is presented in Table 3. When no exceedances of a threshold have been reported by a country this is indicated with a dash (-).

Exceedance of the threshold value of 360 µg/m3 for hourly values has been observed at one station only:

Country	Stationname & City	Date, time	Max conc (µg/m3)

Portugal

Coimbra

26 April 1995, 4.00

365

Table 3. Maximum ozone concentrations (in µg/m3) measured during a period of exceedance of threshold values (reference period 1 January - 31 December 1995). A dash (-) indicates that no exceedances have been observed at any of the monitoring stations in the Member State. A question mark (?) indicates that exceedances are observed but no information on maximum values is available.

	180	200	360	110	110	65
	1h	1h	1h	8h (a)	8h (b)	24h

AT	260	260	-	190	209	166
BE	284	284	-	242	243	187
DE	293	293	-	227	245	203
DK	202	202	-	179	191	142
ES	292	292	-	164	189	155
FI	-	-	-	131	136	122
FR	319	319	-	234	233	177
GB	268	268	-	244	246	205
GR	352	352	-	155	243	142
IE	232	232	-	175	174	143
IT	300	338	-	227	258	175
LU	253	253	-	190	204	167
NL	279	279	-	195	224	143
PT	365	365	365	?	?	173
SE	206	206	-	183	194	140

(a) based on three non-overlapping eight hourly values between 0.00-8.00; 8.00-16.00; 16.00-24.00;
(b) based on the eight hourly value between 12.00-20.00.

This exceedance has been observed in a period during which exceedances of the 180 µg/m3 threshold have not been reported at any other station in the EU. An explanation of this exceptional level (e.g. local ozone formation, intrusion of stratospheric ozone or malfunc-tioning of the monitoring system) cannot be made without further information on local conditions at the time of exceedance. This study is currently being carried out by Portugal.

Map 1. Location of ozone monitoring stations as reported by Member States in the framework of the Ozone Directive for the reference period 1995.

As the number of monitoring stations differs widely from country to country, the absolute number of exceedances is less suitable for comparison. Therefore, the concept of "occurrence of exceedances" is introduced here. Occurrence of exceedances is defined as the averaged number of observed exceedances per country, that is, the total number of exceedances summed over all the stations of a country divided by the total number of reporting stations. A summary of occurrence of exceedances is presented in Table 4. Full details on the number of exceedances at the individual stations is presented in Table I.1 of Annex I.

The longest period of consecutive days on which thresholds were exceeded and the average length of an exceedance period are presented in Tables I.2 and I.3 of Annex I.

For each of the Member States the lowest and highest 50-, 98- and 99.9-percentile values observed at individual stations with a data-coverage of 75% or more, are presented in Table 5. In this table also information on the maximum values is included. Note that the maximum 8-hourly concentration, as reported in Table 5 is based on a moving average and may therefore differ from the values in Table 3 which are based on fixed 8-hourly periods. Detailed information on the percentile values and maximum concentrations observed at individual monitoring stations is given in Annex I, Table I.4.

Table 4. Occurrence of exceedances (reference period 1 January - 31 December 1995);
n.a. = no information available.

threshold value (µg/m3)

	Number of stations (c)	180 1h	200 1h	110 8h (a)	110 8h (b)	65 24h

AT	110	1.2	0.3	33.6	38.7	111.3
BE	20	10.6	4.9	24.7	30.4	45.6
DE	342	5.3	2.2	24.4	33.4	73.3
DK	6	1.0	0.3	6.8	11.5	103.8
ES	86	0.5	0.2	11.3	12.9	52.7
FI	11	0.0	0.0	3.5	4.8	116.0
FR	110	3.4	1.4	20.3	20.3	40.3
GB	32	3.1	1.3	10.8	13.8	58.4
GR	10	18.5	10.2	9.9	53.8	103.2
IE	6	2.2	1.0	15.0	14.3	117.5
IT	68	5.5	2.9	22.8	28.9	45.6
LU	5	8.6	2.6	33.0	31.0	77.8
NL	37	6.9	3.7	14.5	25.5	44.5
PT	9	2.3	1.5	n.a.	n.a.	51.9
SE	6	0.3	0.2	10.8	11.3	138.7
EU-15	858	4.1	1.8	22.1	28.3	70.1

(a) based on three non-overlapping eight hourly values between 0.00-8.00; 8.00-16.00; 16.00-24.00;
(b) based on the eight hourly value between 12.00-20.00;
(c) note that small differences in the number of stations reporting for each of the threshold levels may occur.

A further discussion on the reported data for 1995 is given in the following chapters. A short comparison between the ozone levels in 1994 and 1995 will be given in paragraph 4.5. Percentile values for previous years (1989-1995) have been reported by four Member States and are briefly discussed in paragraph 4.6.

Table 5. Range in reported 50-, 98- and 99.9-percentile values and maximum observed values (based on hourly and moving eight-hourly averaged concentrations) observed at individual monitoring stations in Member States (in µg/m3), period 1 January - 31 December 1995; n.a.= no information available.

1995	1h-P50	1h-P98	1h-P99.9	1h-MAX

range	min	max	min	max	min	max	min	max

AT	9	96	88	153	117	201	128	260
BE	27	50	126	167	187	235	214	284
DE	9	92	70	182	113	242	148	293
DK	45	63	104	112	156	183	177	202
ES	11	78	34	141	56	232	62	292
FI	34	70	79	116	100	133	109	147
FR	13	81	70	170	112	265	30	319
GB	14	68	72	160	116	244	28	268
GR	18	59	79	173	101	275	110	352
IE	48	72	100	125	n.a.	n.a.	160	233
IT	7	69	64	179	107	246	95	338
LU	16	62	87	167	149	210	178	253
NL	17	53	86	153	164	232	175	279
PT	10	90	32	137	57	227	81	365
SE	57	67	93	117	115	183	122	206

1995	8h-P50	8h-P98	8h-P99.9	8h-MAX

range	min	max	min	max	min	max	min	max

AT	13	95	81	148	109	183	119	211
BE	27	55	114	152	168	219	184	251
DE	15	91	62	177	104	232	130	267
DK	45	63	98	107	139	168	164	189
ES	11	77	31	138	47	159	41	188
FI	34	70	74	113	91	131	99	137
FR	14	81	65	155	94	225	28	241
GB	16	68	66	156	102	238	24	252
GR	20	59	72	155	89	223	98	259
IE	47	71	94	120	n.a.	n.a.	145	190
IT	44	44	146	146	n.a.	n.a.	66	244
LU	19	62	77	164	131	200	146	205
NL	19	53	79	140	141	214	156	227
PT	10	91	30	144	54	205	61	226
SE	56	67	90	114	112	171	114	194