Table 4.
Comparison statistics for hourly gas measurements at South Dekalb NCore site.
| Pollutant | Manufacturer, Model | Testing component ID | Sampling Time (Days) | Original Sensor Measurement | Comparison with reference | Reference Concentrationd (ppb) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| r > 0.5 | OLS Regression (FEM = a × Sensor + b) |
Converted to reference unit | ||||||||||
| Mean | Unit | CV | r2 | Slope (a) | Intercept (b) | |||||||
| O3 | Aeroqual, SM50 | SAFT-1 | 251 | 0.0177 | ppm | 1.03 | Y | 0.94 | 888.26 | 2.56 | 18.3 | 18.3 |
| SAFT-2 | 168 | 0.0182 | ppm | 1.06 | Y | 0.94 | 811.52 | 2.84 | 17.6 | 17.6 | ||
| WSN-N4 | 281 | 0.016 | ppm | 0.93 | Y | 0.82 | 955.26 | 2.91 | 18.2 | 18.2 | ||
| Cairpol, CairClipa | SAFT-1c | 194 | 7.2 | ppb | 2.38 | Y | 0.88 | 0.851 | 12.451 | 18.6 | 18.6 | |
| WSN-N4 | 285 | 6.3 | ppb | 2.67 | Y | 0.68 | 0.685 | 12.203 | 16.5 | 16.7 | ||
| AQMesh Corp, AQMesh | SAFT-1 | 111 | 11.8 | ppb | 0.81 | N | n/a | 14.9 | ||||
| SAFT-2 | 110 | 11.6 | ppb | 0.71 | N | n/a | 14.8 | |||||
| NO2 | Cairpol, CairClipb | SAFT-1c | 194 | 0.18 | ppb | 40 | Y | 0.57 | 0.955 | 11.391 | 11.6 | 11.7 |
| WSN-N4 | 285 | 1 | ppb | 9.32 | N | n/a | 11.2 | |||||
| AQ Mesh Corp, AQMesh | SAFT-1 | 111 | 17.5 | ppb | 0.80 | N | n/a | 10.0 | ||||
| SAFT-2 | 110 | 29.1 | ppb | 0.65 | N | n/a | 10.0 | |||||
| Wicked Device, Air Quality Egg (e2v MiCS-2710) | SAFT-1 | 121 | 31514.7 | NA | 2.58 | N | n/a | 10.6 | ||||
| SAFT-2 | 196 | 35927.7 | NA | 2.1 | N | n/a | 12.1 | |||||
| SAFT-3 | 115 | 32873.4 | NA | 2.46 | N | n/a | 11.3 | |||||
| NO | AQMesh Corp, AQMesh |
SAFT-1 | 111 | 19.4 | ppb | 1.84 | Y | 0.77 | 0.892 | 1.060 | 18.4 | 18.3 |
| SAFT-2 | 110 | 21.8 | ppb | 1.76 | Y | 0.87 | 0.883 | -0.765 | 18.5 | 18.5 | ||
| CO | AQMesh Corp, AQMesh | SAFT-1 | 111 | 318.3 | ppb | 0.70 | Y | 0.63 | 8.09×10−4 | 6.95×10−2 | 0.3272 | 326.2 |
| SAFT-2 | 110 | 345.4 | ppb | 0.68 | Y | 0.68 | 7.99×10−4 | 5.12×10−2 | 0.3272 | 326.3 | ||
| Wicked Device, Air Quality Egg (e2v MiCS-5525) | SAFT-1 | 121 | 28500 | NA | 0.25 | N | n/a | 328.1 | ||||
| SAFT-2 | 196 | 25636.7 | NA | 0.28 | N | n/a | 328.1 | |||||
| SAFT-3 | 115 | 24882.8 | NA | 0.31 | N | n/a | 307.1 | |||||
| SO2 | AQMesh Corp, AQMesh | SAFT-1 | 111 | 41.8 | ppb | 0.79 | N | n/a | 0.243 | |||
| SAFT-2 | 110 | 39.9 | ppb | 0.89 | N | n/a | 0.245 | |||||
a
By subtracting the FEM NO2 data
b
by subtracting the FEM O3 data
c
after sensor replacement on 2014/11/15
d
FEM instrument – O3: Thermo Fisher Scientific, 49I; NO2: Thermo Fisher Scientific, 42C; NO: Fisher Scientific, 42C; CO: Thermo Fisher Scientific, 48C; SO2: Thermo Fisher Scientific, 43i-TLE (Waltham, MA, USA)
e
Reference monitor original units are in ppm; NA: not available; n/a: not applicable.