Table 3 Summary data of air pollutants and weather conditions described in the included studies

Mariani et al. [37]

36.5

48.3

Mariani et al. [14]

Healthy subjects (HS)

14.9

22.9

Allergic rinitis (AR)

Lin et al. [38]

Low

20.3 ± 6.5

45.9 ± 24.5

23.7 ± 13.7

7.7 ± 2.4

71.9 ± 41.8

25.5 ± 5.9

68.4 ± 15.1

High

59.1 ± 8.1

Li et al. [39]

Region A

72.5

100

N.A

N.A

N.A

Region B

72.5

100

N.A

N.A

N.A

Region C

92.5

135

N.A

N.A

N.A

Qin et al. [34]

Pre-smog

80–128

150

Post-smog

217–287

314–416

Zhao et al. [32]

S, M

101.0 (0.9)

41.1 (4.5)

14.2 (1.0)

93.3 (22.4)

8.9 (1.0)

64.2 (2.6)

S, D7

85.1 (2.7)

41.1 (11.3)

14.0 (3.7)

117.7 (29.6)

10.9 (0.9)

62.7 (11.7)

S, D0

110 (12)

46 (21)

8 (12)

52 (152)

6.5 (10.5)

77 (18)

F, M

32.7 (2.3)

45.2 (0.8)

12.2 (0.8)

165.2 (21.1)

22.4 (0.4)

63.6 (0.2)

F, D7

28.7 (1.1)

45.2 (0.8)

10.6 (3.2)

92.4 (27.8)

20.6 (1.1)

83.6 (15.4)

F, D0

22 (19.5)

36 (11.25)

13 (2.25)

155 (4.5)

23.0 (2.6)

64 (12)

Zhao et al. [10]

W1, M

100.9 ± 12.6

48.1 ± 8.0

19.8 ± 3.1

66.3 ± 14.8

4.7 ± 3.6

53.0 ± 5.5

W1, D7

95.1 ± 34.3

49.4 ± 8.1

18.4 ± 5.3

82.8 ± 47.4

5.7 ± 4.7

56.6 ± 15.4

W1, D0

73.2 ± 30.7

51.8 ± 20.2

18.0 ± 5.2

91.9 ± 58.9

9.2 ± 7.8

55.7 ± 19.8

W2, M

109.7 ± 6.5

63.8 ± 3.1

18.1 ± 1.4

45.8 ± 1.7

3.2 ± 2.4

54.5 ± 4.6

W2, D7

110.5 ± 31.4

68.0 ± 7.7

18.2 ± 3.5

45.3 ± 9.5

2.0 ± 2.3

52.0 ± 6.1

W2, D0

97.0 ± 51.0

74.4 ± 17.8

21.5 ± 5.5

45.3 ± 23.0

3.5 ± 3.2

46.0 ± 10.2

Du et al. [36]

D0

5 (6)

32 (15)

11.2 (2.9)

27 (12)

D30

90 (36)

213 (159)

3.8 (2.4)

51 (37)

D60

21 (23)

59 (37)

−4.8 (3.6)

26 (13.8)

Li et al. [26]

S1

222.6 ± 111.9

134.4 ± 59.0

54.6 ± 29.0

29.1 ± 13.7

101.2 ± 72.2

26.6 ± 2.9

57.5 ± 15.6

S2

99.1 ± 67.8

111.4 ± 68.5

52.7 ± 23.4

45.8 ± 17.8

23.7 ± 24.2

5.8 ± 3.6

36.8 ± 15.1