3. Summary of reported data for 1995

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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

   
 
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