Table 4.
Mean PM10 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.
| PM10 Units (μg/m3) |
||||||
|---|---|---|---|---|---|---|
| Level 4 |
Level 3 |
Level 2 |
||||
| OB | LTM | OB | LTM | OB | LTM | |
| North Upper (NU) | 10.1 (4.3) | 11.5 (2.5) | 14.3 (4.6) | 15.3 (3.1) | 13.4 (6.1) | 16.1 (3.5) |
| −12.06% | −4.6% | −13.8% | ||||
| North Central (NC) | 11.3 (3.9) | 14.2 (3.8) | 17.0 (5.5) | 16.6 (3.5) | 19.8 (9.0) | 14.9 (3.3) |
| −16.7% | 6.6% | 30.9% | ||||
| North Lower (NL) | 9.2 (3.9) | 11.5 (2.5) | 12.5 (3.4) | 13.7 (1.9) | 14.5 (5.2) | 15.0 (2.4) |
| −18.8% | −8.1% | −4.5% | ||||
| South Upper (SU) | 9.0 (3.5) | 13.8 (2.8) | 18.7 (6.5) | 19.8 (3.4) | 25.1 (8.4) | 25.3 (6 .0) |
| −34.1% | −6.0% | −1.1% | ||||
| South Lower (SL) | 13.4 (6.6) | 15.1 (3.6) | 19.2 (8.6) | 20.8 (4.0) | 28.1 (12.4) | 25.7 (7.4) |
| −11.5% | −7.2% | 9.2% | ||||