1. Sensor Hardware & Data Collection
We utilize the PM1006K optical dust sensor (LED Particle Sensor) for monitoring Particulate Matter (PM2.5). This sensor uses laser scattering technology to detect particles with aerodynamic diameter of 0.3µm to 10µm.
- Measurement Range: 0 to 1,000 µg/m³
- Accuracy: ±20% or ±20 µg/m³
- Response Time: 8 seconds
- Sampling Rate: Data collected every 30 seconds
2. Data Aggregation
To provide meaningful insights over time, raw 30-second readings are aggregated (averaged) into larger time blocks depending on the selected view. This helps smooth out noise and identify trends.
| Time View | Aggregation Interval | Data Range |
|---|---|---|
| 1 Day | 1 Hour | Last 24 Hours |
| 7 Days | 2 Hours | Last 168 Hours |
| 15 Days | 3 Hours | Last 360 Hours |
| 30 Days | 6 Hours | Last 720 Hours |
3. AQI Calculation Standard
We calculate the Air Quality Index (AQI) based on the standard linear interpolation formula for PM2.5 (µg/m³). The breakpoints used in our system are as follows:
Reference Breakpoints
| PM2.5 Range (µg/m³) | AQI Range |
|---|---|
| 0.0 – 12.0 | 0 – 50 (Good) |
| 12.1 – 35.4 | 51 – 100 (Moderate) |
| 35.5 – 55.4 | 101 – 150 (Unhealthy for Sensitive) |
| 55.5 – 150.4 | 151 – 200 (Unhealthy) |
| 150.5 – 250.4 | 201 – 300 (Very Unhealthy) |
| 250.5 – 350.4 | 301 – 400 (Hazardous) |
Sample Calculation
Let's calculate AQI for a PM2.5 reading of 45.0 µg/m³.
1. Identify Range: 45.0 falls between 35.5 (Clow) and 55.4 (Chigh).
2. Identify AQI Range: Corresponding AQI limits are 101 (Ilow) and 150 (Ihigh).
2. Identify AQI Range: Corresponding AQI limits are 101 (Ilow) and 150 (Ihigh).
AQI = [ (Ihigh - Ilow) / (Chigh - Clow) ] × (C - Clow) + Ilow
AQI = [ (150 - 101) / (55.4 - 35.5) ] × (45.0 - 35.5) + 101
AQI = [ 49 / 19.9 ] × 9.5 + 101
AQI = 2.46 × 9.5 + 101
AQI = 23.37 + 101 ≈ 124
AQI = [ (150 - 101) / (55.4 - 35.5) ] × (45.0 - 35.5) + 101
AQI = [ 49 / 19.9 ] × 9.5 + 101
AQI = 2.46 × 9.5 + 101
AQI = 23.37 + 101 ≈ 124