Table 1.
Average concentrations and 99% confidence intervals for the selected atmospheric pollutants, and local meteorological data during March to May 2017–2019 vs. 2020, and the respective relative changes.
| Pollutant |
A: Mean 2017–2019 (CI) (historical) |
B: Mean 2020 (CI) (current) |
Relative Change (B-A)/A, % |
|||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM10 (μg∙m−3) | 75 | ( | 73 | – | 77 | ) | 71 | ( | 69 | – | 73 | ) | −5.2 | ( | −13 | – | 2.1 | )⁎ |
| PM2.5 (μg∙m−3) | 27 | ( | 26 | – | 28 | ) | 24 | ( | 23 | – | 25 | ) | −11 | ( | −18 | – | −3.6 | )⁎⁎ |
| NOx (μg∙m−3) | 113 | ( | 109 | – | 117 | ) | 52 | ( | 49 | – | 55 | ) | −54 | ( | −63 | – | −45 | ) ⁎⁎ |
| NO2 (μg∙m−3) | 57 | ( | 56 | – | 58 | ) | 33 | ( | 32 | – | 34 | ) | −42 | ( | −49 | – | −36 | ) ⁎⁎ |
| NO (μg∙m−3) | 56 | ( | 53 | – | 59 | ) | 19 | ( | 17 | – | 21 | ) | −66 | ( | −79 | – | −52 | ) ⁎⁎ |
| CO (mg∙m−3) | 0.96 | ( | 0.93 | – | 0.99 | ) | 0.83 | ( | 0.80 | – | 0.87 | ) | −13 | ( | −22 | – | −3.9 | ) ⁎⁎ |
| O3 (μg∙m−3) | 25 | ( | 24 | – | 26 | ) | 41 | ( | 38 | – | 43 | ) | 63 | ( | 41 | – | 84 | ) ⁎⁎ |
| T (°C) | 16 | ( | 15 | – | 16 | ) | 16 | ( | 16 | – | 17 | ) | 4.3 | ( | 1.3 | – | 10 | ) ⁎ |
| HR (%) | 58 | ( | 58 | – | 59 | ) | 57 | ( | 55 | – | 58 | ) | −3.0 | ( | −7.9 | – | 1.9 | ) ⁎ |
| Ws (m s−1) | 1.01 | ( | 0.98 | – | 1.03 | ) | 0.92 | ( | 0.88 | – | 0.97 | ) | −8.2 | ( | −18 | – | 1.7 | ) ⁎ |
*p > 0.01 **p < 0.001.