Air at the Kopaonik station
Raška, Serbia
Network: Agency for Environmental Protection · Station code: RS0047A
This year, up to yesterday (October 6)
at least
48 days
with an 8-hour average of ozone (O₃) above the target value of 120 µg/m³.
The target value allows 25 such days a year, averaged over three years.
In 2025: 42 days above the limit, the target value allows 25 as a three-year average.
Worst day: July 19, 2026, O₃ 151 µg/m³ as a daily average, 1.3 times the limit.
Daily average for 182 of 279 days · data for 2026 not yet finally verified · Yardstick: EU limits (Directive 2008/50/EC)
Moderate
Air now · Measured at 21:00
Latest values
Latest value: 21:00
| Pollutant | Value | Level |
|---|---|---|
| O₃ | 113.4 µg/m³ | Moderate |
| SO₂ | 10.2 µg/m³ | Good |
How the air is changing
Over the last seven days there was more O₃ in the air than the week before.
- O₃: average 92.2 µg/m³, week before 75.6 µg/m³
- SO₂: average 8.3 µg/m³, week before 8.6 µg/m³
Last month there was less O₃ in the air than the month before.
- O₃: average 91.7 µg/m³, month before 112.9 µg/m³
- SO₂: average 9.1 µg/m³, month before 8.2 µg/m³
Show
Ozone O₃
113.4
Nowµg/m³
Measured at 21:00
100.8
Last 24 hoursµg/m³
measured in 96 % of hours · provisional
92.2
Last 7 daysµg/m³
measured in 98 % of hours · provisional
90.3
Last 30 daysµg/m³
measured in 99 % of hours · provisional
too few readings
Last 12 months
measured in 72 % of hours · provisional
Days in 2023: O₃, 8-hour average above 120 µg/m³
29 days above the limit.
- above the limit
- below the limit
- too few readings for the day
Days above the limit with values (29)
- Mar 19 121
- Apr 14 121
- Jun 11 122
- Jun 19 128
- Jun 20 131
- Jun 22 121
- Jul 1 121
- Jul 2 124
- Jul 8 121
- Jul 9 122
- Jul 10 125
- Jul 11 130
- Jul 13 132
- Jul 16 132
- Jul 18 122
- Jul 23 123
- Jul 24 124
- Jul 26 132
- Aug 1 122
- Aug 4 142
- Aug 5 141
- Aug 6 141
- Aug 22 125
- Aug 23 120
- Aug 24 121
- Aug 28 122
- Aug 29 137
- Sep 12 122
- Sep 13 127
Values in µg/m³, limit 120 µg/m³.
Months of 2023
| Month | Days above 120 | Highest 8 h | No readings |
|---|---|---|---|
| January | 0 | 99 | 0 |
| February | 0 | 106 | 0 |
| March | 1 above the number allowed | 121 | 0 |
| April | 1 above the number allowed | 121 | 0 |
| May | 0 | 117 | 0 |
| June | 4 above the number allowed | 131 | 0 |
| July | 12 above the number allowed | 132 | 0 |
| August | 9 above the number allowed | 142 | 0 |
| September | 2 above the number allowed | 127 | 0 |
| October | 0 | 109 | 0 |
| November | 0 | 99 | 0 |
| December | 0 | 101 | 0 |
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.
Values as a table
| Hour to | µg/m³ | Note |
|---|---|---|
| Wednesday, 10/7 | ||
| 21:00 | 113.4 | |
| 20:00 | 110.3 | |
| 19:00 | 111.4 | |
| 18:00 | 116 | |
| 17:00 | 114.1 | |
| 16:00 | 112.1 | |
| 15:00 | 111 | |
| 14:00 | 110.1 | |
| 13:00 | 110.2 | |
| 12:00 | 109.3 | |
| 11:00 | 109.2 | |
| 10:00 | 106.1 | |
| 09:00 | 99.3 | |
| 08:00 | 83.5 | |
| 07:00 | 81.5 | |
| 06:00 | 82.6 | |
| 05:00 | 84.2 | |
| 04:00 | 98.6 | |
| 03:00 | 102.5 | |
| 02:00 | 107 | |
| 01:00 | 100.4 | |
| Tuesday, 10/6 | ||
| 00:00 | 73.4 | |
| 23:00 | 72.3 | |
| 22:00 | 55.6 | |
| 21:00 | 118.6 | |
| 20:00 | 112.8 | |
| 19:00 | 121.2 | |
| 18:00 | 125.1 | |
| 17:00 | 118.2 | |
| 16:00 | 114.5 | |
| 15:00 | 111.7 | |
| 14:00 | 110.5 | |
| 13:00 | 111.2 | |
| 12:00 | 111 | |
| 11:00 | 111.2 | |
| 10:00 | 91.1 | |
| 09:00 | 49.6 | |
| 08:00 | 65.9 | |
| 07:00 | 81.4 | |
| 06:00 | 80.9 | |
| 05:00 | 81.2 | |
| 03:00 | 82.4 | |
| 02:00 | 80.5 | |
| 01:00 | 80.5 | |
| Monday, 10/5 | ||
| 00:00 | 78.7 | |
| 23:00 | 79.1 | |
| 22:00 | 93 | |
| 21:00 | 95.7 | |
| 20:00 | 83.5 | |
| 19:00 | 101.1 | |
| 18:00 | 106.5 | |
| 17:00 | 106 | |
| 16:00 | 106.5 | |
| 15:00 | 105.2 | |
| 14:00 | 104.5 | |
| 13:00 | 103 | |
| 12:00 | 103 | |
| 11:00 | 100.8 | |
| 10:00 | 87 | |
| 09:00 | 58.1 | |
| 08:00 | 74.1 | |
| 07:00 | 79.1 | |
| 06:00 | 81.3 | |
| 05:00 | 98.2 | |
| 04:00 | 99.7 | |
| 03:00 | 91.4 | |
| 02:00 | 94.3 | |
| 01:00 | 93 | |
| Sunday, 10/4 | ||
| 00:00 | 97.8 | |
| 23:00 | 98.4 | |
| 22:00 | 93.5 | |
| 21:00 | 93.4 | |
| 20:00 | 96.3 | |
| 19:00 | 98.2 | |
| 18:00 | 98.7 | |
| 17:00 | 98.7 | |
| 16:00 | 100.3 | |
| 15:00 | 96.2 | |
| 14:00 | 95.3 | |
| 13:00 | 98.7 | |
| 12:00 | 99.1 | |
| 11:00 | 96.5 | |
| 10:00 | 91.9 | |
| 09:00 | 89.7 | |
| 08:00 | 95.5 | |
| 07:00 | 94.2 | |
| 06:00 | 93.7 | |
| 05:00 | 91.8 | |
| 04:00 | 94.6 | |
| 03:00 | 100 | |
| 02:00 | 89.8 | |
| 01:00 | 87.9 | |
| Saturday, 10/3 | ||
| 00:00 | 90.8 | |
| 23:00 | 90.5 | |
| 22:00 | 78.2 | |
| 21:00 | 88.6 | |
| 20:00 | 97.5 | |
| 19:00 | 97.9 | |
| 18:00 | 97.8 | |
| 17:00 | 96.8 | |
| 16:00 | 94.7 | |
| 15:00 | 92.6 | |
| 14:00 | 92.9 | |
| 13:00 | 93 | |
| 12:00 | 94.5 | |
| 11:00 | 94.4 | |
| 10:00 | 96.1 | |
| 09:00 | 95.4 | |
| 08:00 | 96.2 | |
| 07:00 | 95.3 | |
| 06:00 | 96 | |
| 05:00 | 96.1 | |
| 04:00 | 96.8 | |
| 02:00 | 96 | |
| 01:00 | 95.5 | |
| Friday, 10/2 | ||
| 00:00 | 97.6 | |
| 23:00 | 100.2 | |
| 22:00 | 99.7 | |
| 21:00 | 94.3 | |
| 20:00 | 92.4 | |
| 19:00 | 99.6 | |
| 18:00 | 101.5 | |
| 17:00 | 100.4 | |
| 16:00 | 98.8 | |
| 15:00 | 98 | |
| 14:00 | 96.8 | |
| 13:00 | 97.2 | |
| 12:00 | 94.4 | |
| 11:00 | 93.2 | |
| 10:00 | 90.7 | |
| 09:00 | 88.6 | |
| 08:00 | 91.4 | |
| 07:00 | 91.8 | |
| 06:00 | 93 | |
| 05:00 | 93 | |
| 04:00 | 94.2 | |
| 03:00 | 91.7 | |
| 02:00 | 92.2 | |
| 01:00 | 90.4 | |
| Thursday, 10/1 | ||
| 00:00 | 88.1 | |
| 23:00 | 87.3 | |
| 22:00 | 91.1 | |
| 21:00 | 90.8 | |
| 20:00 | 91.4 | |
| 19:00 | 93.9 | |
| 18:00 | 94.6 | |
| 17:00 | 91.1 | |
| 16:00 | 91.6 | |
| 15:00 | 90.4 | |
| 14:00 | 88 | |
| 13:00 | 90 | |
| 12:00 | 90.5 | |
| 11:00 | 88.7 | |
| 10:00 | 86.1 | |
| 09:00 | 85.4 | |
| 08:00 | 87.4 | |
| 07:00 | 88.2 | |
| 06:00 | 88.5 | |
| 05:00 | 86.7 | |
| 04:00 | 89.7 | |
| 03:00 | 88.2 | |
| 02:00 | 85.4 | |
| 01:00 | 86.8 | |
| Wednesday, 9/30 | ||
| 00:00 | 86.4 | |
Values as a table
| Day | µg/m³ | Note |
|---|---|---|
| Tue, 10/6 | 116.6 | provisional |
| Mon, 10/5 | 104.5 | provisional |
| Sun, 10/4 | 98.2 | provisional |
| Sat, 10/3 | 97.6 | provisional |
| Fri, 10/2 | 98.4 | provisional |
| Thu, 10/1 | 91.9 | provisional |
| Wed, 9/30 | 87.6 | provisional |
| Tue, 9/29 | 96.8 | provisional |
| Mon, 9/28 | 98.2 | provisional |
| Sun, 9/27 | 85.9 | provisional |
| Sat, 9/26 | 82.3 | provisional |
| Fri, 9/25 | 80.5 | provisional |
| Thu, 9/24 | 77.6 | provisional |
| Wed, 9/23 | 68.8 | provisional |
| Tue, 9/22 | 81.7 | provisional |
| Mon, 9/21 | 105.6 | provisional |
| Sun, 9/20 | 111.9 | provisional |
| Sat, 9/19 | 99.7 | provisional |
| Fri, 9/18 | 109.1 | provisional |
| Thu, 9/17 | 110.4 | provisional |
| Wed, 9/16 | 94.4 | provisional |
| Tue, 9/15 | 91.8 | provisional |
| Mon, 9/14 | 99.2 | provisional |
| Sun, 9/13 | 99.2 | provisional |
| Sat, 9/12 | 115.3 | provisional |
| Fri, 9/11 | 138.7 | above the limit · provisional |
| Thu, 9/10 | 144 | above the limit · provisional |
| Wed, 9/9 | 146 | above the limit · provisional |
| Tue, 9/8 | 116 | provisional |
| Mon, 9/7 | 103.5 | provisional |
Values as a table
| Month | µg/m³ | a year earlier | Note |
|---|---|---|---|
| October 2026 so far | 93.4 | 67.6 | measured in 99 % of hours · provisional · year before: same days |
| September 2026 | 91.7 | 85.6 | measured in 99 % of hours · provisional |
| August 2026 | 112.9 | 104.5 | measured in 99 % of hours · provisional |
| July 2026 | 95.8 | 99.8 | measured in 96 % of hours · provisional |
| June 2026 | 99.3 | 105 | measured in 98 % of hours · provisional |
| May 2026 | 107.8 | 105.1 | measured in 98 % of hours · provisional |
| April 2026 | 108 | 94.1 | measured in 81 % of hours · provisional · 5 days without data from the station |
| March 2026 | too few readings | 91.4 | 31 days without data from the station |
| February 2026 | too few readings | 78.9 | 28 days without data from the station |
| January 2026 | too few readings | 77.1 | 31 days without data from the station |
| December 2025 | 76.8 | 67.6 | measured in 96 % of hours · verified |
| November 2025 | 74.8 | 60.3 | measured in 99 % of hours · verified |
O₃ by year
Yardstick: EU limits (Directive 2008/50/EC)
| Measure | 2026* | 2025 | 2024 |
|---|---|---|---|
| Days with 8-hour average above 120 µg/m³ (target value 25) | ≥ 48 | 42 | 41 |
| Annual average, µg/m³ | too few | 89.1 | 88.5 |
| Highest 8-hour average, µg/m³ | 151July 19 | 149August 28 | 149July 20 |
| Hours measured | 65 % | 98 % | 98 % |
| Days without any reading from the station | 95 | 0 | 2 |
* 2026 up to October 6; 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.
■ 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 2023
| Day | Highest 8 h | Times the limit |
|---|---|---|
| Aug 4, 2023 | 142 | 1.2 × |
| Aug 6, 2023 | 141 | 1.2 × |
| Aug 5, 2023 | 141 | 1.2 × |
| Aug 29, 2023 | 137 | 1.1 × |
| Jul 26, 2023 | 132 | 1.1 × |
Daily average in µg/m³, daily limit 120 µg/m³. Days with the same unverified value over many hours are not on this list.
Sulphur dioxide SO₂
10.2
Nowµg/m³
Measured at 21:00
10.8
Last 24 hoursµg/m³
measured in 96 % of hours · provisional
8.3
Last 7 daysµg/m³
measured in 99 % of hours · provisional
9
Last 30 daysµg/m³
measured in 99 % of hours · provisional
too few readings
Last 12 months
measured in 73 % of hours · provisional
Values as a table
| Hour to | µg/m³ | Note |
|---|---|---|
| Wednesday, 10/7 | ||
| 21:00 | 10.2 | |
| 20:00 | 10.5 | |
| 19:00 | 10.3 | |
| 18:00 | 10.4 | |
| 17:00 | 10.5 | |
| 16:00 | 10.2 | |
| 15:00 | 10.3 | |
| 14:00 | 9.4 | |
| 13:00 | 10.2 | |
| 12:00 | 8.8 | |
| 11:00 | 8.6 | |
| 10:00 | 8.7 | |
| 09:00 | 8.4 | |
| 08:00 | 8.8 | |
| 07:00 | 8.5 | |
| 06:00 | 8.9 | |
| 05:00 | 9.1 | |
| 04:00 | 10.2 | |
| 03:00 | 10.6 | |
| 02:00 | 11.9 | |
| 01:00 | 12 | |
| Tuesday, 10/6 | ||
| 00:00 | 32.3 | |
| 23:00 | 10.3 | |
| 22:00 | 10.6 | |
| 21:00 | 10 | |
| 20:00 | 10.7 | |
| 19:00 | 10.9 | |
| 18:00 | 10 | |
| 17:00 | 10.4 | |
| 16:00 | 10.6 | |
| 15:00 | 10.1 | |
| 14:00 | 9.7 | |
| 13:00 | 9.5 | |
| 12:00 | 9.7 | |
| 11:00 | 9.2 | |
| 10:00 | 8 | |
| 09:00 | 8.6 | |
| 08:00 | 8.5 | |
| 07:00 | 8.3 | |
| 06:00 | 7.9 | |
| 05:00 | 6.6 | |
| 04:00 | 7.3 | |
| 03:00 | 6.6 | |
| 02:00 | 7.5 | |
| 01:00 | 7.9 | |
| Monday, 10/5 | ||
| 00:00 | 8.2 | |
| 23:00 | 8.9 | |
| 22:00 | 9.6 | |
| 21:00 | 9.7 | |
| 20:00 | 8.7 | |
| 19:00 | 9.2 | |
| 18:00 | 9.5 | |
| 17:00 | 9.1 | |
| 16:00 | 8.6 | |
| 15:00 | 8.3 | |
| 14:00 | 8.7 | |
| 13:00 | 9 | |
| 12:00 | 9.1 | |
| 11:00 | 8.3 | |
| 10:00 | 8.4 | |
| 09:00 | 8.4 | |
| 08:00 | 8.4 | |
| 07:00 | 8 | |
| 06:00 | 7.9 | |
| 05:00 | 7.9 | |
| 04:00 | 7.8 | |
| 03:00 | 7.8 | |
| 02:00 | 7.7 | |
| 01:00 | 7.4 | |
| Sunday, 10/4 | ||
| 00:00 | 7.2 | |
| 23:00 | 8.4 | |
| 22:00 | 8.9 | |
| 21:00 | 8.4 | |
| 20:00 | 8.5 | |
| 19:00 | 8.8 | |
| 18:00 | 8.5 | |
| 17:00 | 8.3 | |
| 16:00 | 8 | |
| 15:00 | 8.8 | |
| 14:00 | 8.2 | |
| 13:00 | 7.5 | |
| 12:00 | 7.9 | |
| 11:00 | 7.5 | |
| 10:00 | 7.3 | |
| 09:00 | 7.2 | |
| 08:00 | 7.2 | |
| 07:00 | 7.7 | |
| 06:00 | 7.4 | |
| 05:00 | 7.1 | |
| 04:00 | 7.2 | |
| 03:00 | 7.6 | |
| 02:00 | 7.2 | |
| 01:00 | 7.4 | |
| Saturday, 10/3 | ||
| 00:00 | 7.3 | |
| 23:00 | 7.3 | |
| 22:00 | 8.1 | |
| 21:00 | 9 | |
| 20:00 | 7.8 | |
| 19:00 | 8.1 | |
| 18:00 | 8.5 | |
| 17:00 | 8.6 | |
| 16:00 | 8 | |
| 15:00 | 8.3 | |
| 14:00 | 8.3 | |
| 13:00 | 8.5 | |
| 12:00 | 7.9 | |
| 11:00 | 7.4 | |
| 10:00 | 7.3 | |
| 09:00 | 7.6 | |
| 08:00 | 7.6 | |
| 07:00 | 6.9 | |
| 06:00 | 7.9 | |
| 05:00 | 7.6 | |
| 04:00 | 7.5 | |
| 03:00 | 7.1 | |
| 02:00 | 7.1 | |
| 01:00 | 7.2 | |
| Friday, 10/2 | ||
| 00:00 | 7.6 | |
| 23:00 | 8.2 | |
| 22:00 | 8 | |
| 21:00 | 8.3 | |
| 20:00 | 8.4 | |
| 19:00 | 7.9 | |
| 18:00 | 7.9 | |
| 17:00 | 8 | |
| 16:00 | 8.7 | |
| 15:00 | 8.3 | |
| 14:00 | 8 | |
| 13:00 | 7.4 | |
| 12:00 | 7.9 | |
| 11:00 | 7.7 | |
| 10:00 | 7.3 | |
| 09:00 | 7.4 | |
| 08:00 | 7.4 | |
| 07:00 | 5.9 | |
| 05:00 | 7.7 | |
| 04:00 | 7.3 | |
| 03:00 | 7.8 | |
| 02:00 | 7.7 | |
| 01:00 | 7.5 | |
| Thursday, 10/1 | ||
| 00:00 | 7.4 | |
| 23:00 | 8 | |
| 22:00 | 8.5 | |
| 21:00 | 8.7 | |
| 20:00 | 8.2 | |
| 19:00 | 8 | |
| 18:00 | 8.3 | |
| 17:00 | 8.4 | |
| 16:00 | 9 | |
| 15:00 | 8.6 | |
| 14:00 | 8.5 | |
| 13:00 | 8 | |
| 12:00 | 8.4 | |
| 11:00 | 7.8 | |
| 10:00 | 7.9 | |
| 09:00 | 8.3 | |
| 08:00 | 8.4 | |
| 07:00 | 7.8 | |
| 06:00 | 7.8 | |
| 05:00 | 7.6 | |
| 04:00 | 8.1 | |
| 03:00 | 7.7 | |
| 02:00 | 7.7 | |
| 01:00 | 8.1 | |
| Wednesday, 9/30 | ||
| 00:00 | 7.6 | |
Values as a table
| Day | µg/m³ | Note |
|---|---|---|
| Tue, 10/6 | 10.1 | provisional |
| Mon, 10/5 | 8.5 | provisional |
| Sun, 10/4 | 7.8 | provisional |
| Sat, 10/3 | 7.8 | provisional |
| Fri, 10/2 | 7.8 | provisional |
| Thu, 10/1 | 8.2 | provisional |
| Wed, 9/30 | 7.9 | provisional |
| Tue, 9/29 | 8.5 | provisional |
| Mon, 9/28 | 8.7 | provisional |
| Sun, 9/27 | 7.9 | provisional |
| Sat, 9/26 | 8.6 | provisional |
| Fri, 9/25 | 8.9 | provisional |
| Thu, 9/24 | 8.7 | provisional |
| Wed, 9/23 | 8.8 | provisional |
| Tue, 9/22 | 10 | provisional |
| Mon, 9/21 | 10.2 | provisional |
| Sun, 9/20 | 9.9 | provisional |
| Sat, 9/19 | 8.6 | provisional |
| Fri, 9/18 | 10.3 | provisional |
| Thu, 9/17 | 10.7 | provisional |
| Wed, 9/16 | 9 | provisional |
| Tue, 9/15 | 8 | provisional |
| Mon, 9/14 | 8.7 | provisional |
| Sun, 9/13 | 8.6 | provisional |
| Sat, 9/12 | 8.3 | provisional |
| Fri, 9/11 | 11.2 | provisional |
| Thu, 9/10 | 10 | provisional |
| Wed, 9/9 | 12.4 | provisional |
| Tue, 9/8 | 8.4 | provisional |
| Mon, 9/7 | 7.7 | provisional |
Values as a table
| Month | µg/m³ | a year earlier | Note |
|---|---|---|---|
| October 2026 so far | 8.4 | 5.8 | measured in 99 % of hours · provisional · year before: same days |
| September 2026 | 9.1 | 7.2 | measured in 99 % of hours · provisional |
| August 2026 | 8.2 | 9.1 | measured in 99 % of hours · provisional |
| July 2026 | 7.1 | 8.4 | measured in 99 % of hours · provisional |
| June 2026 | 6.1 | 7.3 | measured in 99 % of hours · provisional |
| May 2026 | 7.2 | 8 | measured in 99 % of hours · provisional |
| April 2026 | 8 | 8.2 | measured in 82 % of hours · provisional · 5 days without data from the station |
| March 2026 | too few readings | 8.1 | 31 days without data from the station |
| February 2026 | too few readings | 7.1 | 28 days without data from the station |
| January 2026 | too few readings | 7.4 | 31 days without data from the station |
| December 2025 | 6.6 | 8.8 | measured in 99 % of hours · verified |
| November 2025 | 7.3 | 6.9 | measured in 93 % of hours · verified |
SO₂ by year
Yardstick: EU limits (Directive 2008/50/EC)
| Measure | 2026* | 2025 | 2024 |
|---|---|---|---|
| Days above 125 µg/m³ (allowed 3) | 0² | 0 | 0 |
| Hours above 350 µg/m³ (allowed 24) | 0² | 0 | 0 |
| Hours above 500 µg/m³, three hours in a row (alert threshold) | 0 | 0 | 0 |
| Annual average, µg/m³ | too few | 7.5 | 5.9 |
| Highest daily average, µg/m³ | 12September 9 | 13August 28 | 12December 24 |
| Highest hourly value, µg/m³ | 42May 25 | 32February 3 | 45July 27 |
| Hours measured | 65 % | 97 % | 98 % |
| Days without any reading from the station | 95 | 0 | 2 |
* 2026 up to October 6; 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.
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.
There is no allowed number for the warning and alert thresholds: every such hour or day is in red.
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: 95
1 outage, 2,280 hours in total in the last 12 months.
Timeline of outages from October 7, 2025 to today
| From | To | Duration |
|---|---|---|
| Jan 1, 2026 00:00 | Apr 6, 2026 01:00 | 95 days |
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 Agency for Environmental Protection. 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.
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