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. 2020 Aug 21;28(1):775–788. doi: 10.1007/s11356-020-10483-y

Table 2.

Descriptive statistics of air quality before the events

City Var Before the event During the event After the event
Mean Std. Skewness Kurtosis IQR Range Mean Std. Skewness Kurtosis IQR Range Mean Std. Skewness Kurtosis IQR Range
Wuhan AQI 80.5 37.15 0.27 1.72 58 122 67.3 18.56 0.29 1.53 33 51 85.07 22.49 − 0.93 3.12 29 88
PM2.5 30.4 11.40 − 0.65 2.23 17 43 33.5 8.96 0.16 1.89 13 26 48.23 18.41 − 0.15 2.36 29 72
PM10 55.6 21.74 0.11 2.23 28 82 54.3 10.15 0.75 2.12 18 29 94.8 30.41 − 0.59 2.65 38 114
SO2 10.67 3.80 0.32 1.77 7 12 8.5 1.27 0.69 2.60 1 4 11.37 3.55 0.59 2.85 4 14
CO 0.86 0.17 − 0.03 1.76 0.3 0.5 0.86 0.22 -0.56 1.85 0.4 0.6 0.96 0.23 − 0.31 2.35 0.3 0.8
NO2 40.5 20.33 0.98 2.78 26 68 48.8 16.34 0.39 2.23 19 62 61.97 22.79 − 0.04 1.83 38 78
O3 126.87 52.39 − 0.01 1.73 91 187 103.2 37.71 − 0.25 1.57 69 102 80.13 32.16 − 0.06 1.81 48 115
Chengdu AQI 63.93 27.15 1.49 4.96 25 116 120.18 36.76 0.41 2.22 45 114 61.5 31.80 1.40 3.73 27 117
PM2.5 18.67 8.25 0.67 2.70 14 31 30.55 11.5 0.55 1.82 20 33 26 11.91 0.04 2.73 15 50
PM10 33.77 14.54 0.58 2.59 21 56 59.73 21.48 0.43 1.58 35 57 41.77 17.94 0.36 3.33 21 81
SO2 4.47 0.63 0.97 2.90 1 2 6.91 2.66 1.83 5.66 3 9 5.33 1.32 1.19 3.78 2 5
CO 0.73 0.10 − 0.28 2.59 0.1 0.4 0.8 0.09 0 1.375 0.2 0.2 0.80 0.13 − 0.78 3.17 0.2 0.5
NO2 34.43 9.87 0.30 2.07 15 35 44 9.24 -0.11 1.92 12 29 33.6 8.51 − 0.42 2.92 12 36
O3 107.2 39.06 0.86 3.41 50 167 180.18 41.44 0.22 2.19 51 132 96.5 47.87 1.07 2.91 56 172
Zhengzhou AQI 105.97 28.38 − 0.05 2.63 41 115 69.67 53.11 0.98 2.39 61 144 88.63 39.91 0.23 1.53 78 134
PM2.5 27.67 9.19 0.25 1.91 18 30 26.89 20.37 0.86 2.36 30 58 30.6 10.79 − 0.36 2.04 17 38
PM10 61.37 13.44 − 0.64 3.89 19 63 50.44 32.6 0.38 1.64 58 87 67.8 26.13 − 0.29 1.8 48 86
SO2 6.27 2.82 0.70 3.31 4 12 6.33 2.18 0.55 1.90 3 6 7.37 2.79 1.19 4.34 3 12
CO 0.80 0.22 1.96 7.13 0.2 1 0.81 0.16 1.51 5.16 0 0.6 0.90 0.22 0.87 4.51 0.3 1.1
NO2 33.7 7.91 − 0.08 2.39 13 32 26.33 5.29 0.03 1.52 10 13 42.57 14.63 0.52 2.58 22 57
O3 163.53 35.50 -0.47 2.86 46 153 105.44 73.65 0.78 2.04 112 197 130.37 62.13 − 0.09 1.5 127 201
Taiyuan AQI 110.37 32.32 − 0.12 2.35 48 133 86.6 29.95 1.14 2.92 36 88 74.87 27.95 0.98 3.13 36 110
PM2.5 36.37 12.72 0.34 2.95 21 57 25.8 15.75 1.25 3.42 17 48 29.43 10.98 0.03 1.96 18 40
PM10 60.8 18.62 − 0.03 2.14 27 74 54.6 19.71 0.43 1.88 29 57 62.43 21.99 − 0.23 2.48 31 87
SO2 8.07 2.35 − 0.15 2.17 4 9 10.2 2.82 0.51 1.57 6 7 11.7 3.78 0.15 2.94 5 17
CO 0.84 0.13 − 0.43 2.99 0.2 0.6 0.73 0.24 0.37 1.62 0.5 0.6 0.83 0.19 0.53 3.02 0.2 0.8
NO2 32.53 8.31 0.43 2.04 14 30 34.5 8.81 0.52 2.82 11 31 45.77 9.58 0.32 3.14 11 42
O3 168.8 38.88 − 0.42 2.62 54 163 136.6 39.82 0.70 2.64 46 134 114.43 46.17 0.20 2.5 57 185