Table 5.
Mean PM2.5 concentrations for COVID-19 alert levels (OB), compared to the LTM (2015–19) for the same dates; standard deviations are in parentheses. The percentage change describes the increase or decrease in observed 2020 concentration compared to the LTM.
| PM2.5 Units (μg/m3) |
||||||
|---|---|---|---|---|---|---|
| Level 4 |
Level 3 |
Level 2 |
||||
| OB | LTM | OB | LTM | OB | LTM | |
| North Upper (NU) | 6.6 (3.2) | 6.4 (2.1) | 11.0 (4.4) | 10.4 (3.3) | 11.7 (5.8) | 11.2 (4.1) |
| −2.0% | 6.7% | 3.8% | ||||
| North Central (NC) | 5.4 (2.3) | 6.4 (2.7) | 8.5 (3.7) | 11.3 (3.9) | 9.9 (5.9) | 11.6 (4.1) |
| −16.7% | −25.7% | −12.9% | ||||
| North Lower (NL) | 5.5 (2.9) | 5.7 (1.7) | 9.3 (5.1) | 8.0 (2.3) | 11.9 (5.8) | 10.9 (3.1) |
| −5.3% | 13.9% | 5.4% | ||||
| South Upper (SU) | 7.1 (4.1) | 9.2 (3.6) | 16.2 (7.9) | 16.9 (3.7) | 28.3 (9.7) | 25.1 (7.0) |
| −22.6% | −4.4% | 12.5% | ||||
| South Lower (SL) | 8.0 (4.5) | 9.6 (3.4) | 11.1 (5.0) | 13.1 (4.6) | 17.8 (7.0) | 13.1 (5.2) |
| −14.4% | −14.0% | 35.3% | ||||