Index comparison
European AQI vs U.S. AQI: why the numbers and labels differ
European AQI and U.S. AQI are separate public communication systems. They use different category boundaries and labels, so a shared numeral does not carry a shared interpretation. AirAgora always displays the scheme name.
European AQI
70
Poor in this scheme
U.S. AQI
70
Moderate in this scheme
Same numeral, different rules
Two systems built for public communication
Both indexes organize pollutant information into categories, but they were not designed as interchangeable units. The European index uses good, fair, moderate, poor, very poor, and extremely poor. The U.S. index uses good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy, and hazardous.
The category vocabularies already show why a direct conversion is misleading. Each system has its own breakpoints and pollutant conventions. A number without the scheme name is incomplete metadata.
Published category bands
The EEA documents the European category bands, while AirNow documents the U.S. bands. The published systems use different numerical ranges and pollutant conventions.
Even where category words sound similar, the underlying numerical range and pollutant logic differ. The right way to compare two screenshots is by scheme, category, pollutant, time, and provenance—not by assuming the raw values share one axis.
| European AQI | U.S. AQI | Direct conversion? |
|---|---|---|
| 0–20 Good | 0–50 Good | No |
| >20–40 Fair | 51–100 Moderate | No |
| >40–60 Moderate | 101–150 Unhealthy for sensitive groups | No |
| >60 and higher: Poor → Extremely poor | 151 and higher: Unhealthy → Hazardous | No |
Why AirAgora does not publish a converter
A converter would suggest mathematical equivalence where none has been established and could hide pollutant-specific averaging differences. AirAgora therefore keeps this comparison educational rather than using either regulatory system as its runtime label.
The live planner displays OpenWeather’s official 1–5 scale. Its internal 0–1 severity comes from documented pollutant concentration bands and is used only inside the deterministic comparison.
Jurisdiction is separate from language
Interface language changes translation and formatting, not the meaning of a regulatory index. Any European or U.S. AQI example must keep its own scheme name attached.
AirAgora’s current live product does not select between these two systems by country. It displays the OpenWeather 1–5 provider scale worldwide and keeps regulatory comparisons on educational pages.
How category differences affect alerts and planning
An alert crossing must be evaluated inside the OpenWeather provider scale. A threshold copied from a different AQI system would not preserve meaning. The same is true for phrases such as “moderate”: users need the scheme context before interpreting the category.
AirAgora stores the OpenWeather provider scale with recommendation snapshots and notification trigger details. This preserves a later explanation and prevents a language switch from silently changing the environmental scale.
- Compare category names only with their scheme attached.
- Do not use one fixed numeric threshold across different AQIs.
- Keep concentration units separate from index values.
- Treat comparison-scale labeling as an explicit limitation.
What both systems still cannot promise
Neither index is a personal exposure meter or a universal guarantee. A category summarizes pollutant information for public communication; a person’s location, time, activity, indoor environment, and health context are not all captured by one number.
AirAgora uses relative planning language and links to official sources. During severe conditions, public warnings remain primary and are never made a Premium-only feature.
Direct answers
Frequently asked questions
Is European AQI 50 equal to U.S. AQI 50?
No. The two systems have different category boundaries and pollutant conventions. Equal numerals do not establish equal meaning.
Why does European AQI have a “fair” category?
“Fair” is part of the European category vocabulary documented by OpenWeather/EEA. The U.S. system uses a different sequence and breakpoints.
Which live scale does AirAgora use in Europe?
The same official OpenWeather 1–5 provider scale used elsewhere. It is not labeled European AQI.
Does changing language change the scale?
No. Locale changes translation and formatting; the provider scale remains OpenWeather 1–5.
How can AirAgora compare hours without converting regulatory AQIs?
It derives internal severity from documented pollutant concentration bands and never publishes that score as an official AQI.
Can I set the same alert threshold for both systems?
That would not preserve the same category meaning. Thresholds must be interpreted inside the named scheme and should not be copied blindly.
Evidence register
Sources and further reading
The links below identify the primary references used on this page. Selection, summary, and presentation are AirAgora modifications.
Keep exploring
AirAgora provides informational planning guidance, not medical advice. Local conditions can differ from modeled forecasts; follow official guidance during severe events.