How we work
Methodology
How we detect and classify sirocco dust events
Last reviewed · Apr 23, 2026
Data Sources
We aggregate data from multiple trusted meteorological sources to provide accurate air quality information.
PM10 Thresholds
Air quality levels are classified based on PM10 particle concentration (particles ≤10µm in diameter).
| Level | PM10 Range | Health Impact |
|---|---|---|
| Good | 0–20 µg/m³ | Minimal health impact expected. Generally safe for outdoor activities. |
| Moderate | 21–50 µg/m³ | Sensitive groups may notice mild symptoms. Corresponds to roughly the WHO 24-hour guideline level (≈45 µg/m³). Individual sensitivity varies. |
| Unfavorable | 51–150 µg/m³ | Some people may experience symptoms. Official guidance typically advises limiting outdoor activities. |
| Very Unfavorable | >150 µg/m³ | Official guidance for this level typically advises staying indoors with windows closed and limiting outdoor exposure. Consult official health authorities. |
Reference: WHO Air Quality Guidelines (2021). These are general thresholds. Individual sensitivity varies.
Sirocco Dust Detection
Our algorithm distinguishes Saharan dust (sirocco) from urban pollution using multiple signals:
- 1.PM10 concentration exceeds 50 µg/m³
- 2.Saharan dust concentration > 30 µg/m³ (indicates significant desert dust)
- 3.Dust-to-PM10 ratio ≥ 60% (confirms Saharan origin vs. urban pollution)
When all criteria are met, the episode is classified as "sirocco dust". High dust alone (>100 µg/m³) triggers detection regardless of ratio.
Status labels (Sirocco Dust, No Sirocco Dust, Sirocco Dust Expected) are derived from scientific data using the criteria above. They are not official meteorological warnings.
Hazy sky vs. ground-level air
Saharan dust often travels high up (1 to 3 km) without mixing down to the surface. The sky can look milky or hazy while the air you actually breathe stays clean. Our headline reflects the air at ground level, with a note when dust is passing overhead.
- ·Ground level (what you breathe): measured from PM10 and dust concentration. This drives our Sirocco Dust / No Sirocco Dust status.
- ·Sky (what you see): estimated from total-column aerosol optical depth (AOD) plus high-altitude wind direction. That is how we can show “Sirocco dust aloft” even when ground-level air is good.
When official sources or cameras show haze but our status says the surface is clear, both can be right: the dust is up high, not at ground level.
Update Frequency
Data is refreshed automatically every 6 hours.
- Air quality data: Every 6 hours
- Forecast data: Every 6 hours
- SKIRON dust maps: Every 6 hours
Limitations
- Forecasts are model-based and may differ from actual conditions.
- Air quality can vary significantly within short distances.
- Observation points represent approximate areas based on reference coordinates. Actual conditions may differ within each area.
- For official warnings, always consult your national meteorological authority.