Air quality — how it is calculated
The score reflects the expected level of fine particulate matter PM2.5 around the address. Data is annual averages from the Sensor.Community archive (SDS011) for Sofia, not real-time values — refreshed annually. Distance interpolation (IDW). No sensors in range → neutral score of 50 in the composite.
What we measure
PM2.5 (µg/m³) from Sensor.Community (SDS011). Daily averages from the archive are computed over a window of up to ~1 year and an annual mean is recorded per sensor. For each address: sensors up to 3 km (5 km if needed), IDW, then a linear scale 0–100: 5 µg/m³ (WHO) → 100, 15 µg/m³ → 0 — intentionally narrow for the real range of citizen sensors in Sofia.
Scale 0–100 (WHO)
| Score | Description |
|---|---|
| 90–100 | Interpolated PM2.5 ≈ up to ~6.5 µg/m³ (close to WHO annual mean guideline) |
| 70–89 | ≈ 6.5–8 µg/m³ |
| 50–69 | ≈ 8–10 µg/m³ |
| 30–49 | ≈ 10–12 µg/m³ |
| 0–29 | ≈ above ~12 µg/m³ (toward the model upper bound of 15 µg/m³) |
Data and updates
We use the Sensor.Community citizen network (SDS011) in Sofia. From the archive we compute annual averages per sensor — a stable estimate that does not depend on momentary weather conditions. Refreshed annually with a 365-day window.
What we do not measure
We do not model ozone, NO₂, or other pollutants separately. We do not account for indoor microclimate or filters. Official IAOS stations may be used for cross-referencing in a future version.
Model version: airQuality v1.2.