Table II.
Results of statistical test of the hypothesis that the signal levels were higher when the air cleaning unit (ACU) was not in operation on 3rd August 2021 compared with a matched period on 4th August 2021 when it was in operation
| Signal | Sensor ID | ACU off mean (SD) | ACU on mean (SD) | Significance P-value | Effect size Cliff's delta | Effect magnitude |
|---|---|---|---|---|---|---|
| PM1 | G | 3.73 (1.30) | 1.03 (0.41) | <0.001 | 0.99 | Large |
| F | 5.05 (2.35) | 1.10 (0.71) | <0.001 | 0.96 | Large | |
| E | 2.83 (0.70) | 0.89 (0.40) | <0.001 | 0.98 | Large | |
| A | 2.96 (0.87) | 0.35 (0.24) | <0.001 | 1.00 | Large | |
| B | 2.61 (0.57) | 0.90 (0.43) | <0.001 | 0.96 | Large | |
| C | 2.60 (0.57) | 0.82 (0.38) | <0.001 | 0.98 | Large | |
| D |
2.64 (0.61) |
0.82 (0.39) |
<0.001 |
0.98 | Large |
|
| PM2.5 | G | 0.39 (0.31) | 0.06 (0.03) | <0.001 | 0.97 | Large |
| F | 0.75 (0.65) | 0.09 (0.16) | <0.001 | 0.92 | Large | |
| E | 0.22 (0.13) | 0.06 (0.07) | <0.001 | 0.93 | Large | |
| A | 0.20 (0.14) | 0.02 (0.01) | <0.001 | 1.00 | Large | |
| B | 0.20 (0.11) | 0.06 (0.07) | <0.001 | 0.90 | Large | |
| C | 0.15 (0.08) | 0.05 (0.04) | <0.001 | 0.93 | Large | |
| D |
0.17 (0.09) |
0.05 (0.04) |
<0.001 |
0.93 |
Large |
|
| PM4 | G | 0.15 (0.19) | <0.01 (0.01) | <0.001 | 0.59 | Large |
| F | 0.37 (0.43) | 0.022 (0.10) | <0.001 | 0.63 | Large | |
| E | 0.04 (0.07) | <0.01 (0.04) | <0.001 | 0.33 | Small | |
| A | 0.04 (0.09) | <0.01 (<0.01) | <0.001 | 0.27 | Small | |
| B | 0.04 (0.07) | 0.010 (0.04) | <0.001 | 0.32 | Small | |
| C | 0.02 (0.05) | <0.01 (0.02) | <0.001 | 0.22 | Small | |
| D |
0.03 (0.06) |
<0.01 (0.02) |
<0.001 |
0.34 |
Medium |
|
| PM10 | G | 0.03 (0.04) | <0.01 (<0.01) | <0.001 | 0.55 | Large |
| F | 0.07 (0.09) | <0.01 (0.02) | <0.001 | 0.60 | Large | |
| E | 0.01 (0.02) | <0.01 (<0.01) | <0.001 | 0.26 | Small | |
| A | 0.02 (0.04) | <0.01 (<0.01) | <0.001 | 0.26 | Small | |
| B | 0.01 (0.01) | <0.01 (<0.01) | <0.001 | 0.24 | Small | |
| C | 0.01 (0.03) | <0.01 (0.01) | <0.001 | 0.20 | Small | |
| D |
0.02 (0.03) |
<0.01 (0.01) |
<0.001 |
0.33 |
Small |
|
| CO2 | G | 815.18 (139.89) | 513.28 (109.67) | <0.001 | 0.90 | Large |
| F | 734.24 (80.02) | 479.59 (111.88) | <0.001 | 0.88 | Large | |
| E | 691.24 (72.78) | 501.26 (72.28) | <0.001 | 0.92 | Large | |
| A | 713.82 (80.28) | 499.45 (78.06) | <0.001 | 0.91 | Large | |
| B | 818.86 (115.04) | 520.79 (105.35) | <0.001 | 0.93 | Large | |
| C | 833.17 (121.85) | 494.87 (85.35) | <0.001 | 0.95 | Large | |
| D |
748.61 (113.94) |
447.10 (102.95) |
<0.001 |
0.93 |
Large |
|
| VP | All sensors | 1.37 (0.05) | 1.18 (0.06) | <0.001 | 0.98 | Large |
PM, particulate matter; PM1, PM fraction <1 μm diameter; PM2.5, PM fraction between 1 and 2.5 μm diameter; PM4, PM fraction between 2.5 and 4 μm diameter; PM10, PM fraction between 4 and 10 μm diameter; CO2, carbon dioxide; VP, vapour pressure; SD, standard deviation.
All results were strongly significant after Bonferroni's correction.