Table 2 Average monthly and annual PM10 (µg/m³) and PM1 (µg/m³) during the 2022–2023 school year by treatment group.
From: Classroom air quality in a randomized crossover trial with portable HEPA air cleaners
PM10 (µg/m³) | PM1 (µg/m³) | |||||
|---|---|---|---|---|---|---|
HEPA | Non-HEPA | HEPA | Non-HEPA | |||
Month | Mean (SD) | Mean (SD) | p-value | Mean (SD) | Mean (SD) | p-value |
Jul 2022 | 1.297 (1.273) | 1.807 (4.238) | 0.293 | 1.205 (1.206) | 1.710 (3.875) | 0.256 |
Aug 2022 | 0.978 (0.836) | 1.940 (2.904) | 0.004 | 0.833 (0.755) | 1.737 (2.611) | 0.003 |
Sep 2022 | 0.903 (0.873) | 1.866 (2.699) | 0.002 | 0.700 (0.763) | 1.611 (2.402) | 0.001 |
Oct 2022 | 1.250 (0.982) | 2.357 (3.537) | 0.007 | 1.026 (0.869) | 2.089 (3.222) | 0.004 |
Nov 2022 | 0.866 (0.914) | 1.360 (1.064) | 0.001 | 0.712 (0.847) | 1.184 (1.028) | 0.001 |
Dec 2022 | 1.315 (1.246) | 1.805 (1.175) | 0.008 | 1.175 (1.193) | 1.652 (1.139) | 0.008 |
Jan 2023 | 1.003 (1.633) | 1.361 (1.651) | 0.161 | 0.802 (1.509) | 1.133 (1.442) | 0.149 |
Feb 2023 | 0.683 (0.645) | 1.210 (1.790) | 0.014 | 0.481 (0.520) | 0.932 (1.606) | 0.018 |
Mar 2023 | 0.758 (2.353) | 1.000 (3.563) | 0.604 | 0.428 (0.927) | 0.823 (3.265) | 0.294 |
Apr 2023 | 1.206 (1.236) | 1.984 (2.383) | 0.010 | 0.921 (0.871) | 1.726 (2.168) | 0.003 |
May 2023 | 0.855 (1.207) | 1.175 (1.640) | 0.165 | 0.617 (0.845) | 0.990 (1.613) | 0.071 |
Jun 2023 | 0.693 (0.793) | 1.009 (0.830) | 0.017 | 0.518 (0.660) | 0.824 (0.772) | 0.009 |
Sep 2022 – May 2023 | 0.992 (1.323) | 1.572 (2.372) | < 0.001 | 0.771 (0.987) | 1.352 (2.170) | <0.001 |
