Frequently Asked Questions

PlainAirQuality is an independent data portal published by Kiznis Studio. It synthesizes air-quality observations from the European Environment Agency (EEA), Copernicus Atmosphere Monitoring Service (CAMS), and national agencies (UBA Germany, ADEME France, ISPRA Italy, GIOS Poland, Defra UK, and 23 others) for 28 European countries. Every country, station, and pollutant page links back to the underlying official source dataset, with the EU regulatory limit and WHO 2021 guideline displayed side by side.

All 27 EU member states plus the United Kingdom. The EU-27 are Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, and Sweden. The UK is included as a co-publisher of equivalent regulatory data under the 2010 Air Quality Standards Regulations (post-Brexit Defra/AURN network remains methodologically aligned with EEA reporting).

The seven pollutants regulated by the EU Ambient Air Quality Directive 2008/50/EC: PM2.5 (fine particulate matter), PM10 (coarse particulate matter), NO2 (nitrogen dioxide), O3 (ground-level ozone), SO2 (sulfur dioxide), CO (carbon monoxide), and C6H6 (benzene). Each pollutant has its own detail page covering the EU limit value, WHO 2021 guideline, primary emission sources, health-impact summary, and EN-standard reference measurement method.

The EU limit is the legally enforceable concentration set by Directive 2008/50/EC. The WHO guideline is the health-evidence target set by the World Health Organization in their 2021 Global Air Quality Guidelines update. The WHO guidelines are substantially stricter — for PM2.5, the WHO annual guideline is 5 micrograms per cubic metre vs the EU limit of 10. For NO2, WHO 2021 is 10 vs the EU limit of 40. A revised EU directive adopted in October 2024 will tighten EU limits closer to WHO guidance by 2030. We show both benchmarks on every detail page so you can see legal compliance and health risk separately.

The primary source is the EEA Air Quality e-Reporting database (Dataflow E1a, validated data) published annually each September under Directive 2008/50/EC and Decision 2011/850/EU. We supplement this with Copernicus Atmosphere Monitoring Service (CAMS) reanalysis for trans-boundary attribution and with real-time feeds from national agencies (UBA, ADEME, ISPRA, GIOS, Defra, APA, CHMI, HSY, SLB-analys, DCMR, RIVM, and others) for the most recent observations. All sources are open-data licensed (CC-BY 4.0 or equivalent).

The EEA validates and publishes the annual dataset in September of the year following the observation year (e.g. 2024 data is published in September 2025). PlainAirQuality refreshes within two weeks of each EEA release. Provisional real-time station data from national agencies is not currently displayed — we wait for EEA validation to ensure regulatory-grade quality.

PM2.5 (particles smaller than 2.5 micrometres in aerodynamic diameter) penetrates deep into the lungs, crosses into the bloodstream, and reaches every organ in the body including the brain. The International Agency for Research on Cancer classifies outdoor PM2.5 as a Group 1 human carcinogen. The European Environment Agency attributes approximately 380,000 premature deaths per year in the EU+UK region to PM2.5 exposure, primarily from cardiovascular disease, stroke, ischemic heart disease, lung cancer, and chronic obstructive pulmonary disease. The WHO 2021 guideline of 5 micrograms per cubic metre reflects the lowest concentration at which adverse effects have been observed across well-conducted cohort studies.

Yes, in most cases. The EU limit (PM2.5 annual: 10 micrograms per cubic metre; NO2 annual: 40 micrograms per cubic metre) is a regulatory threshold; exceeding it triggers air-quality action plan obligations on the member state. The WHO 2021 guideline is a health-evidence target — it is not legally binding. Many European cities sit in the gap between the two: legal under EU law but above the concentration at which health risk is meaningfully elevated according to WHO. The 2024 EU directive revision will close some of this gap by 2030.

EEA station classifications follow EU implementing Decision 2011/850/EU. A traffic station is sited within 10 metres of a road kerb to capture peak roadside exposure. A background station is sited away from any major direct emission source to capture ambient (urban or rural) air. An industrial station is sited within 250 metres of an industrial emission source. Traffic stations typically read 20–40% higher than co-located background stations for NO2 and PM2.5; ozone is the inverse (ozone titrates against NOx, so ozone is often lower at traffic sites).

Recommended citation: PlainAirQuality, "[Page Title]", https://plainairquality.com/[path], accessed [date]. For underlying data, cite the original source — for EEA data: European Environment Agency, Air Quality e-Reporting Database (Dataflow E1a), https://www.eea.europa.eu/en/datahub. For WHO benchmarks: World Health Organization, WHO global air quality guidelines (2021), https://www.who.int/publications/i/item/9789240034228.

PlainAirQuality is a presentation layer. For raw data, please download directly from the official publishers — the EEA Datahub for regulatory observations, Copernicus Atmosphere Data Store for reanalysis, and the national agency portals for real-time feeds. We link to each source from the relevant page so you can verify any number we publish.

No. PlainAirQuality is published by Kiznis Studio, an independent data-journalism publisher. We are not affiliated with the EEA, the European Commission, Copernicus, the WHO, or any member-state government. We do not accept payment from government agencies, industry trade groups, or environmental NGOs for the editorial content on this site.