Pollutant guide
What is PM10? Understanding coarse-particle forecasts
PM10 names a particulate matter size fraction with aerodynamic diameter up to 10 micrometres. The reported concentration includes smaller particles within that boundary, so PM10 and PM2.5 are related fields rather than two independent totals to add together.
Source → method → decision
What belongs in the PM10 size fraction
PM10 covers particulate matter up to a 10-micrometre aerodynamic boundary. Because PM2.5 falls within that broader size range, a PM10 concentration generally includes the fine-particle fraction rather than sitting beside it as a completely separate bucket. Adding PM10 and PM2.5 would therefore double-count part of the modeled mass.
The label says nothing by itself about the exact composition or local origin of the particles. AirAgora deliberately avoids turning a size fraction into claims about traffic, dust, industry, smoke, weather, or season for a city unless a future authoritative source supports that specific statement.
How the provider represents PM10
OpenWeather exposes hourly PM10 concentration and its official 1–5 provider value. The concentration is normally expressed in micrograms per cubic metre; AirAgora derives PM10 severity from the documented concentration bands for internal comparison.
AirAgora retains the provider unit in the detailed table and uses only comparable concentration-band severities when selecting a main pollutant. A PM10 concentration of one numerical size cannot be ranked directly against ozone or nitrogen-dioxide concentrations that use different physical relationships and index rules.
PM10, PM2.5, and the temptation to over-interpret
Seeing both fields can invite a false calculation. Subtracting PM2.5 from PM10 may look like a way to obtain a coarse fraction, but a consumer forecast page should not imply analytical precision that the provider has not documented for that use. Rounding, model behavior, and field definitions matter.
AirAgora shows each provider field as supplied and explains the derived concentration-band severity separately from the official 1–5 category. It does not infer particle chemistry, source apportionment, indoor levels, or personal dose.
Using hourly PM10 patterns for planning
The useful question is whether complete practical windows differ enough to support a decision. AirAgora evaluates consecutive hours, labels the local timezone, and avoids filling missing values. Lower derived PM10 severity can help explain a better period, but the recommendation still considers the strongest supported pollutant severity across each complete window.
When changes are small, the interface says conditions remain broadly similar. When all windows are poor, it identifies only the least polluted available period. This wording keeps relative ranking separate from a claim that the air is universally safe.
- Read PM10 and PM2.5 as overlapping size fractions, not numbers to add.
- Check whether the screen shows concentration or an concentration-band context.
- Use local timestamps and provider update time when comparing hours.
- Keep official severe-event guidance outside any subscription gate.
Grid forecasts and neighborhood differences
OpenWeather data reaches the product through an OpenWeather modeled grid. The documented European and global resolutions are much larger than a block or building. A PM10 plume, road edge, construction site, indoor room, or local monitor can behave differently from the cell average.
That limitation does not make the forecast useless. It changes the claim: the forecast supports a regional hourly comparison, while local observations and official warnings provide different evidence. AirAgora shows provenance so users can tell which kind they are viewing.
Health-safe interpretation
WHO guidance supports taking particulate pollution seriously without pretending that one app can determine individual exposure. AirAgora uses cautious comparative language and never says that a low category eliminates risk. It does not collect diagnoses to generate city-page copy.
If activity needs to be adapted for a particular person, use appropriate public-health or clinical guidance. AirAgora can still help frame the timing question by showing whether the provider models a meaningful change across the day.
Direct answers
Frequently asked questions
Does PM10 include PM2.5?
PM2.5 is within the broader PM10 aerodynamic size boundary, so the reported fractions overlap. They should not be added as if they were independent totals.
What unit is used for PM10?
OpenWeather normally supplies PM10 mass concentration in micrograms per cubic metre (μg/m³). Internal concentration-band severity is separate from the provider’s 1–5 value.
Can I subtract PM2.5 from PM10?
That subtraction may be used in some analytical contexts, but AirAgora does not present it as a precise consumer estimate because model definitions, rounding, and intended use must be reviewed first.
Why can a nearby PM10 monitor differ?
A monitor samples one site, while the modeled OpenWeather forecast represents a modeled grid. Siting, time, terrain, and local conditions can produce different values.
Does a lower PM10 window mean no health risk?
No. It is a relative forecast comparison. AirAgora avoids universal-safe language and directs users to official guidance for severe conditions or personal questions.
How does PM10 affect the main-pollutant label?
Its derived concentration-band severity is compared with the other supported pollutant severities. Raw concentrations with different units are not ranked against each other.
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.