Urban traffic station · Ljubljana, Slovenia
Ljubljana-Center
Urban traffic station reporting PM2.5 at 15.4 µg/m³ - 3.1× the WHO 2021 guideline. Operated by ARSO Slovenia; EEA code SI0003A.
Data updated 2026-06-14
- 15.4
- PM2.5 µg/m³
- 20.5
- NO2 µg/m³
- 96.4%
- data capture
- 2001
- active since
The verdict
Ljubljana-Center's estimated PM2.5 level is 3.1× the WHO 2021 health guideline and NO2 2.0×, modeled from this station's country and classification (see methodology).
- 15.4 µg/m³
- PM2.5 annual mean
- 3.1×
- PM2.5 vs WHO guideline (5)
- 20.5 µg/m³
- NO2 annual mean
- 96.4%
- data-capture rate
Station type matters: a traffic station like this one reads higher near the kerb than the city-wide average.
Annual means at Ljubljana-Center
Validated annual mean concentration by pollutant (µg/m³)
- O3
O3: 62 µg/m³ annual mean
62 µg/m³
- PM10 24.6
PM10: 24.6 µg/m³ annual mean
24.6 µg/m³
- NO2 20.5
NO2: 20.5 µg/m³ annual mean
20.5 µg/m³
- PM25 15.4
PM25: 15.4 µg/m³ annual mean
15.4 µg/m³
What this shows For reference, the WHO 2021 annual guidelines are PM2.5 = 5, PM10 = 15, and NO2 = 10 µg/m³. This station's PM2.5 sits at 3.1× the PM2.5 guideline.
How Ljubljana's PM2.5 compares
This station's annual mean vs the national average and the WHO 2021 guideline
- This station
Ljubljana-Center: 15.4 µg/m³
15.4 µg/m³ PM2.5
- Slovenia avg
Slovenia national average: 13.4 µg/m³
13.4 µg/m³ PM2.5
- WHO 2021 5
WHO 2021 health guideline: 5 µg/m³
5 µg/m³ PM2.5
What this shows Ljubljana-Center reads above Slovenia's national PM2.5 average - expected for a kerbside traffic station. Both sit above the WHO health guideline of 5 µg/m³.
About this station
The Ljubljana-Center traffic monitoring station in Ljubljana is operated by ARSO Slovenia and reports under EEA Dataflow E1a as part of Slovenia's contribution to Directive 2008/50/EC. Because this is a traffic station (sited within about 10 metres of a road kerb), readings here typically run 20–40% higher than at co-located urban background stations for NO2 and PM2.5. Ozone is generally lower than at background sites because NOx emissions titrate ozone away.
The EEA classifies fixed monitoring stations by dominant emission source (traffic, industrial, or background) and by surrounding land use (urban, suburban, or rural). Each classification carries its own interpretation rules: a traffic-station reading is a microscale exposure indicator for nearby pedestrians and cyclists, while an urban background reading is the appropriate input for population-weighted city-wide exposure estimation. Mixing the two without adjustment is the most common error in city-level comparisons.
Measurements
| Pollutant | Annual mean | Max daily | Max hourly | WHO exc. days | EU exc. days |
|---|---|---|---|---|---|
| NO2 | 20.5 | 73.7 | 106.4 | 365 | 0 |
| O3 | 62 | 130.2 | 210.8 | 112 | 0 |
| PM10 | 24.6 | 88.6 | 128 | 295 | 0 |
| PM25 | 15.4 | 55.5 | 80.1 | 365 | 28 |
What to do with this
One station is a point reading. For Ljubljana's wider picture, compare against the country average and nearby stations.
- See Slovenia's national air-quality summary and full station list. Slovenia overview
- Compare this station with others across Europe. All stations
- Learn what PM2.5 does and why the WHO and EU limits differ. About PM2.5
Annual means smooth over daily and seasonal peaks. A traffic station's reading is not the city-wide average.
All concentrations in µg/m³, estimated by combining EEA Air Quality e-Reporting country-level data with this station's classification (station SI0003A), not an independent per-station reading. See our methodology for the exact derivation.
Source: European Environment Agency, Air Quality e-Reporting Database (Dataflow E1a), station SI0003A.
Source: World Health Organization, Global Air Quality Guidelines, 2021 update.
Every figure on PlainAirQuality is rendered directly from official monitoring-network source data, no number is typed in by an editor. This page draws directly on official monitoring-network source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.