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Air at the Celje station

Celje, Slovenia

Network: Slovenian Environment Agency · Station code: SI0001A

This year, up to yesterday (October 7)

at least

24 days

with an 8-hour average of ozone (O₃) above the target value of 120 µg/m³.

Readings are missing for part of the period, so the real number may be higher.

6 days

with a daily average of particulate matter PM10 above the EU limit of 50 µg/m³.

35 days are allowed in the whole year.

Worst day: July 30, 2026, O₃ 140 µg/m³ as a daily average, 1.2 times the limit.

Daily average for 208 of 280 days · data for 2026 not yet finally verified · Yardstick: EU limits (Directive 2008/50/EC)

All figures by year and month

Moderate

Air now · Measured at 22:00

Latest values

Latest value: Wed 22:00

Readings
PollutantValueLevel
PM1024.7 µg/m³Fair
NO₂43 µg/m³Moderate
O₃30.9 µg/m³Good
SO₂5.3 µg/m³Good

How the air is changing

Over the last seven days there was more PM10, PM2.5, and NO₂ in the air than the week before.

  • PM10: average 24.3 µg/m³, week before 16.3 µg/m³
  • PM2.5: average 13.3 µg/m³, week before 9.7 µg/m³
  • NO₂: average 29.8 µg/m³, week before 24.3 µg/m³
  • O₃: too few readings to compare
  • SO₂: average 6.4 µg/m³, week before 5.9 µg/m³

Last month there was more NO₂ and less PM10, PM2.5, and O₃ in the air than the month before.

  • PM10: average 11.5 µg/m³, month before 14.5 µg/m³
  • PM2.5: average 5.9 µg/m³, month before 7.7 µg/m³
  • NO₂: average 18.3 µg/m³, month before 14.9 µg/m³
  • O₃: average 43.7 µg/m³, month before 74.9 µg/m³
  • SO₂: average 5.1 µg/m³, month before 4.9 µg/m³

Show

Ozone O₃

30.9

Nowµg/m³

Measured at 22:00

54.1

Last 24 hoursµg/m³

measured in 75 % of hours · provisional

40.7

Last 7 daysµg/m³

measured in 77 % of hours · provisional

37.5

Last 30 daysµg/m³

measured in 84 % of hours · provisional

too few readings

Last 12 months

measured in 82 % of hours · 1 month with too few readings · provisional

Days in 2025: O₃, 8-hour average above 120 µg/m³

21 days above the limit.

1102031JanFebMarAprMayMay 1: 126 µg/m³, above the limitMay 2: 133 µg/m³, above the limitMay 3: 146 µg/m³, above the limitMay 4: 144 µg/m³, above the limitJunJun 11: 143 µg/m³, above the limitJun 13: 127 µg/m³, above the limitJun 14: 130 µg/m³, above the limitJun 23: 156 µg/m³, above the limitJun 24: 151 µg/m³, above the limitJun 25: 134 µg/m³, above the limitJun 26: 149 µg/m³, above the limitJun 27: 140 µg/m³, above the limitJulJul 2: 144 µg/m³, above the limitJul 3: 133 µg/m³, above the limitJul 4: 128 µg/m³, above the limitJul 19: 135 µg/m³, above the limitJul 20: 134 µg/m³, above the limitAugAug 13: 129 µg/m³, above the limitAug 14: 134 µg/m³, above the limitAug 15: 138 µg/m³, above the limitAug 16: 126 µg/m³, above the limitSepOctNovDec
  • above the limit
  • below the limit
  • too few readings for the day
  • no O₃ data in the EEA database
Days above the limit with values (21)
  1. May 1 126
  2. May 2 133
  3. May 3 146
  4. May 4 144
  5. Jun 11 143
  6. Jun 13 127
  7. Jun 14 130
  8. Jun 23 156
  9. Jun 24 151
  10. Jun 25 134
  11. Jun 26 149
  12. Jun 27 140
  13. Jul 2 144
  14. Jul 3 133
  15. Jul 4 128
  16. Jul 19 135
  17. Jul 20 134
  18. Aug 13 129
  19. Aug 14 134
  20. Aug 15 138
  21. Aug 16 126

Values in µg/m³, limit 120 µg/m³.

Months of 2025

MonthDays above 120Highest 8 hNo readings
January0810
February0770
March01140
April01200
May4 above the number allowed1460
June8 above the number allowed1560
July5 above the number allowed1440
August4 above the number allowed1380
September0950
October0880
November0830
December0220

Values in µg/m³. ■ marks a month with at least one day above the limit; the number allowed applies to the whole year. “No readings”: days on which not a single reading came from the station.

Last 7 days, every hour: O₃ in µg/m³highest 117 µg/m³, latest 31 µg/m³ (22:00)050100150ThuFriSatSunMonTueWedhighest 117latest 31 (22:00)
measuredmodel estimate, not counted
Last 7 days, every hour: O₃ in µg/m³
Values as a table
Hour toµg/m³Note
Wednesday, 10/7
23:0061model estimate, not counted
22:0030.9
21:0041.2
20:0065.3
19:0079.1
18:0092.5
17:0098.6
16:0098.5
15:0097.6
14:00102.5
13:00100.8
12:0090.1
11:0020.8
10:005
05:001.1
04:008.9
03:0010.1
02:0015.9
01:0015.4
Tuesday, 10/6
00:009.3
23:008.6
22:006.4
21:009.9
20:001.4
19:0040.7
18:0084
17:00105.3
16:00103.3
15:0087
14:0070.8
13:0057.5
12:0027
11:009.1
10:000.4
01:000.2
Monday, 10/5
22:006.4
21:004
20:0017.7
19:0028.3
18:0034.2
17:0077.3
16:0076
15:0060.3
14:0056.6
13:0038.9
12:0025.9
11:008.9
10:003.6
03:003.6
02:000.8
01:001.4
Sunday, 10/4
00:0010.5
23:0010
22:003.9
21:004.7
20:0033.4
19:0051.9
18:0070.6
17:00106.7
16:00105.7
15:00106.8
14:00103.6
13:0092.6
12:0074
11:0042.5
10:0029.5
09:008.8
06:001.1
05:001.3
04:004.7
03:003.5
02:006.1
01:0010.5
Saturday, 10/3
00:0010.7
23:0011.7
22:0017
21:0016.9
20:0046.5
19:0052.4
18:0096
17:00108.8
16:00111.2
15:00116.7
14:00106.7
13:0089.8
12:0060.5
11:0036.7
10:0021.3
09:004.5
05:000.6
03:002.4
02:005.2
01:002.5
Friday, 10/2
23:003.8
22:001.7
21:000.4
20:0015.4
19:0018.4
18:0093.4
17:00100.8
16:0092
15:0091.8
14:0085.3
13:0072
12:0042.5
11:0021.4
10:006.9
04:001.7
03:003.6
02:0010.2
01:009.9
Thursday, 10/1
00:0022
23:0015
22:0016.6
21:0018.7
20:0022.9
19:0038
18:0090.6
17:0096.6
16:0096.3
15:0093.2
14:0086
13:0072.3
12:0048.4
11:0027.7
10:009
05:004.5
04:002.1
03:002.9
02:005.2
Last 30 days, highest 8-hour average of the day: O₃ in µg/m³highest 100 µg/m³, latest 89 µg/m³0501001509/109/179/2410/1highest 100latest 89
too few readingstarget value, 120 µg/m³
Last 30 days, highest 8-hour average of the day: O₃ in µg/m³
Values as a table
Dayµg/m³Note
Wed, 10/7too few readings
Tue, 10/6too few readings
Mon, 10/5too few readings
Sun, 10/489provisional
Sat, 10/3too few readings
Fri, 10/2too few readings
Thu, 10/1too few readings
Wed, 9/3077.2provisional
Tue, 9/29too few readings
Mon, 9/28too few readings
Sun, 9/27too few readings
Sat, 9/26too few readings
Fri, 9/2563.9provisional
Thu, 9/24too few readings
Wed, 9/2363provisional
Tue, 9/2255.7provisional
Mon, 9/2159.8provisional
Sun, 9/2062.2provisional
Sat, 9/19too few readings
Fri, 9/1865.5provisional
Thu, 9/17too few readings
Wed, 9/16too few readings
Tue, 9/15too few readings
Mon, 9/1447.6provisional
Sun, 9/1378.4provisional
Sat, 9/1275.3provisional
Fri, 9/1142.4provisional
Thu, 9/1058.2provisional
Wed, 9/981provisional
Tue, 9/8100.4provisional
Last 12 months, monthly average: O₃ in µg/m³highest 75 µg/m³, latest 41 µg/m³050100DecFebAprJunAugOcthighest 75latest 41
Last 12 monthsthis month so fara year earlier
Last 12 months, monthly average: O₃ in µg/m³
Values as a table
Monthµg/m³a year earlierNote
October 2026 so far40.731.9measured in 77 % of hours · provisional · year before: same days
September 202643.733.3measured in 86 % of hours · provisional
August 202674.959.5measured in 100 % of hours · provisional
July 202670.367.8measured in 96 % of hours · provisional
June 202656.381.4measured in 78 % of hours · provisional
May 20266562.2measured in 94 % of hours · provisional
April 202656.459.8measured in 97 % of hours · provisional
March 202650.152.5measured in 84 % of hours · provisional
February 2026too few readings33.3measured in 69 % of hours · provisional
January 202627.637.2measured in 79 % of hours · provisional
December 2025too few readingstoo few readingsmeasured in 47 % of hours · verified
November 2025too few readings21.9measured in 64 % of hours · verified

O₃ by year

Yardstick: EU limits (Directive 2008/50/EC)

Measure2026*20252024
Days with 8-hour average above 120 µg/m³ (target value 25)≥ 24²≥ 21²≥ 7²
Annual average, µg/m³53.7*too few44.8
Highest 8-hour average, µg/m³140July 30156June 23129April 15
Hours measured87 %85 %90 %
Days without any reading from the station000

* 2026 up to October 7; the average since the start of the year is not yet an annual average.

The monitoring networks have not yet finally verified this year’s data. The EEA publishes verified values once a year.

≥ means at least: more than a tenth of the days or hours are missing, so the real number may be higher.

² Too few readings to compare with the number allowed: the figure covers only what was measured.

■ and a figure in red: more than is allowed for the whole year.

The column for 2023 is shown on wider screens.

The worst days of 2025

DayHighest 8 hTimes the limit
Jun 23, 20251561.3 ×
Jun 24, 20251511.3 ×
Jun 26, 20251491.2 ×
May 3, 20251461.2 ×
May 4, 20251441.2 ×

Daily average in µg/m³, daily limit 120 µg/m³. Days with the same unverified value over many hours are not on this list.

Outages in the last 12 months

Every period of at least 24 hours in which no reading arrived from this station.

Days without a reading: 0

Timeline of outages from October 8, 2025 to today

In the last 12 months this station had no outage of 24 hours or longer.

Calculated from the hourly values the EEA publishes. If late values arrive afterwards, an outage gets shorter or disappears.

Where the data comes from

Measured by Slovenian Environment Agency. We take the values from the European Environment Agency (EEA) under the CC BY 4.0 licence.

Values marked provisional have not been fully checked by the network yet. The EEA publishes verified data for the previous year once a year, usually by the end of September.

An hourly value is the average of one hour. We show the end of the hour: the value to 18:00 was measured from 17:00 to 18:00.

A day runs from midnight to midnight local time.

We only show an average when at least three out of four hours in the period have a reading. The EU air quality directive requires this for daily averages, and we apply the same rule to longer periods. We compare an annual average with the EU limit only once 90 % of hours are measured, as the directive requires. For 12 months and for a year we ask for more: if less than 90 % of hours are measured, every full calendar month needs readings for at least half of its hours. Otherwise a whole season could be missing from the average, such as summer, when ozone is highest.

We do not call a difference of up to 10 % a change, nor one of up to 1 µg/m³ at low levels, because weather and measurement uncertainty alone cause differences that size.

When a station sends no reading, the EEA sometimes fills the hour with a model estimate. We draw those hours dashed and leave them out of every average.

The EU limits come from Directive 2008/50/EC. Here they serve as a yardstick for comparison. When more than a tenth of the days or hours are missing, the number of exceedances can only be higher, so we write “at least” in front of it.

How we measure

samoEKO is a brand of samoLabs, Juelich.