Direct air-quality answer
What is PM2.5?
PM2.5 means fine particulate matter represented by an aerodynamic diameter of 2.5 micrometres or smaller. It describes a size fraction, not one chemical substance or one universal source.
Suspended particles
Size matters; source is not inferred
Short answer
PM2.5 means fine particulate matter represented by an aerodynamic diameter of 2.5 micrometres or smaller. It describes a size fraction, not one chemical substance or one universal source.
AirAgora can display modeled PM2.5 concentration and a PM2.5-specific concentration-band context. It does not infer what produced the particles in a city or diagnose an individual response.
Why the size label matters
Particle behavior and health evidence are often organized by aerodynamic size fractions. The concentration is commonly reported in micrograms per cubic metre, while an concentration-band context applies scheme-specific breakpoints and averaging conventions.
A raw concentration and an index number are different quantities. PM2.5 concentration must not be added to ozone, nitrogen dioxide, or an aggregate AQI.
How AirAgora handles the question
OpenWeather provides modeled hourly fields. AirAgora keeps units, named OpenWeather 1–5 scale, source, and timestamp visible. It selects a main pollutant using documented concentration-band severities rather than raw concentrations.
The city corpus never invents local PM2.5 causes. A live value remains modeled at a broad grid resolution and can differ from a nearby monitor or street.
What to check before comparing
Confirm whether a screen shows µg/m³, U.S. concentration-band context, European concentration-band context, or aggregate AQI. Align the hour, location, source, and averaging context.
Use official guidance for severe events and professional guidance for individual concerns. A lower value is relative evidence, not a universal safety promise.
- Size fraction, not one substance
- Concentration and AQI are different
- Source cannot be inferred from value alone
- Modeled grid is not street-level
- Named scheme and units stay visible
Direct answers
Frequently asked questions
Is PM2.5 the same as smoke?
Smoke can contain fine particles, but PM2.5 is a size fraction and can include particles from multiple processes. A value alone does not identify the source.
What unit does AirAgora use for concentration?
The provider field is displayed in micrograms per cubic metre, separate from concentration-band context values.
Is PM2.5 always the main pollutant?
No. AirAgora compares compatible pollutant concentration-band severities for the selected hours.
Can a model show exact PM2.5 on my street?
No. The broad OpenWeather grid can differ from local monitors, roads, buildings, terrain, or plumes.
Does AirAgora treat “What is PM2.5” as a personal guarantee?
AirAgora can display modeled PM2.5 concentration and a PM2.5-specific concentration-band context. It does not infer what produced the particles in a city or diagnose an individual response.
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.