Pollutant guide
What is nitrogen dioxide? Interpreting NO₂ forecast data
Nitrogen dioxide (NO₂) is a gaseous pollutant represented by an hourly modeled concentration and pollutant-specific index component. AirAgora uses those provider fields without inferring a city’s source mix or an individual’s exposure.
Source → method → decision
What the NO₂ field represents
Nitrogen dioxide is a gas, commonly abbreviated NO₂. In OpenWeather’s air-quality response, the hourly field is a modeled near-surface concentration for the provider grid. It is not a sensor reading at the user’s address and does not identify the source responsible for a particular hour.
AirAgora displays the concentration with the provider unit and derives the corresponding documented concentration-band severity for explanation. The gas concentration and the index value are related inputs with different meanings.
Why NO₂ should not be ranked by its raw numeral
Pollutant concentrations are not a common scoreboard. PM2.5 and PM10 describe particle mass fractions, while NO₂ is a gas field; the same numeral does not imply equal severity. Public indexes apply pollutant-specific breakpoints and averaging rules to create communication categories.
The AirAgora main-pollutant rule compares documented per-pollutant concentration-band severities. It never chooses NO₂ merely because its concentration number is larger than another field.
Spatial resolution and local variation
The documented OpenWeather grids are a broad provider grid. Within either area, NO₂ can vary at scales the grid cannot resolve. A point monitor, road edge, elevated location, indoor space, or different hour may not match the cell value.
This is why AirAgora labels data as modeled and shows the update time. A result can support a broad timing comparison while remaining unsuitable as a precise street-level statement.
How NO₂ contributes to the recommended window
The engine evaluates complete two-hour windows from the strongest derived component severity while preserving the official OpenWeather 1–5 category for display. If NO₂ has the highest concentration-band severity under the stable tie order, it appears as the main pollutant.
A named main pollutant is descriptive, not causal. It means the provider’s compatible component was largest in the selected result. It does not prove which activity or source created the modeled concentration.
Using the data for everyday plans
A user can compare local-time windows for general outdoor activity, running or cycling, children outdoors, or opening windows. Activity choices make caution appear earlier where the product rules call for it, but they do not change the underlying ranking or create clinical advice.
For ventilation, AirAgora adds a specific boundary: outside air alone cannot reveal indoor air quality. For all activities, official warnings and local public guidance remain more important during severe events.
- Distinguish NO₂ concentration from the NO₂ concentration-band context.
- Check the OpenWeather provider scale scheme before comparing another service.
- Expect a modeled grid to differ from a point monitor.
- Do not treat the main-pollutant label as source attribution.
A cautious health interpretation
WHO air-quality guidance is a reason to avoid universal-safe claims, not a license for an app to give personal treatment instructions. AirAgora describes relative modeled conditions and provides a route to public sources.
People seeking guidance for symptoms, a diagnosed condition, medication, or a child’s individual needs should use qualified advice. The product does not collect those details to manufacture a more personalized-sounding city page.
Direct answers
Frequently asked questions
What does NO₂ stand for?
NO₂ is nitrogen dioxide, a gaseous pollutant. The OpenWeather field used by AirAgora is an hourly modeled concentration for a forecast grid.
Is NO₂ measured at my address?
No. AirAgora uses modeled OpenWeather forecast grid data. A nearby point monitor or street can show a different value.
Why is the NO₂ concentration not compared directly with PM2.5?
They are different pollutant quantities. AirAgora compares documented concentration-band severities instead of ranking unlike raw concentration units.
When does NO₂ become the main pollutant?
When its pollutant-specific component is highest under the selected OpenWeather scale and deterministic tie rules for the result.
Does “main pollutant” identify the local source?
No. It identifies the largest compatible index component. It does not attribute traffic, industry, weather, or any other source.
Can AirAgora tell whether I should change medication or treatment?
No. AirAgora provides general forecast-based planning information, not diagnosis or treatment advice. Personal decisions require appropriate professional guidance.
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.