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Environmental Sciences Europe

Table 1 Comparison of criteria pollutants during haze and non-haze days (2018–2021) over the YRD region cities

From: Spatiotemporal characterization of aerosols and trace gases over the Yangtze River Delta region, China: impact of trans-boundary pollution and meteorology

Cities

Pollutant

Percent change

Mean PM2.5 concentrations [µg/m3]

Haze days[H]

Non-haze days[N]

[H-N]/N*100

Shanghai

77

28

175%

Nanjing

60

27

122%

Hefei

45

26

73%

Hangzhou

48

28

72%

Mean SO2 concentrations [µg/m3]

 Shanghai

10

07

42%

 Nanjing

9.7

8.5

15%

 Hefei

7

6.25

12%

 Hangzhou

7.77

6.75

15%

Mean NO2 concentrations [µg/m3]

 Shanghai

56

35

60%

 Nanjing

48

33.5

45%

 Hefei

45

35

28%

 Hangzhou

47

32

46%

Mean PM10 concentrations [µg/m3]

 Nanjing

95

60

58%

 Hefei

75

57

31%

 Hangzhou

80

52.5

53%

Mean O3 concentrations [µg/m3]

 Shanghai

94

103

− 9%

 Nanjing

93

123

− 32%

 Hefei

90

113

− 25%

 Hangzhou

85

111

− 30%

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