Table 1.

Comparison of the average values of the PM_2.5 mass concentration (μg/m³) in Xianghe and “2 + 26” cities in Beijing-Tianjin-Hebei and its surrounding areas during the entire measurement period (E) and the three control periods (P1, P2, and P3).

Cities	E	P1	P2	P3
Xianghe	76 ± 80	99 ± 84	114 ± 4	46 ± 35
Beijing	52 ± 53	57 ± 49	68 ± 110	38 ± 37
Tianjin	67 ± 64	106 ± 89	90 ± 58	38 ± 25
Langfang	61 ± 62	79 ± 69	89 ± 84	36 ± 29
Tangshan	67 ± 59	101 ± 70	82 ± 60	38 ± 26
Shijiazhuang	83 ± 65	145 ± 71	114 ± 80	52 ± 33
Baoding	81 ± 80	138 ± 113	121 ± 55	40 ± 23
Handan	78 ± 59	151 ± 63	103 ± 71	40 ± 17
Cangzhou	65 ± 56	119 ± 773	82 ± 79	35 ± 18
Hengshui	67 ± 51	130 ± 60	80 ± 57	37 ± 18
Xingtai	78 ± 59	146 ± 62	99 ± 48	45 ± 22
Taiyuan	68 ± 53	119 ± 72	83 ± 52	55 ± 38
Changzhi	58 ± 43	120 ± 52	66 ± 47	40 ± 21
Jincheng	62 ± 52	129 ± 75	70 ± 28	48 ± 26
Yangquan	59 ± 43	87 ± 48	70 ± 32	60 ± 39
Jinan	62 ± 41	111 ± 47	77 ± 36	38 ± 20
Dezhou	68 ± 59	147 ± 47	81 ± 34	34 ± 20
Liaocheng	71 ± 52	142 ± 68	87 ± 49	40 ± 20
Binzhou	59 ± 46	95 ± 60	69 ± 51	41 ± 26
Zibo	64. ± 41	100 ± 49	76 ± 47	49 ± 29
Jining	72 ± 45	125 ± 41	85 ± 37	44 ± 20
Heze	69 ± 49	139 ± 43	90 ± 50	37 ± 17
Zhengzhou	70 ± 50	130 ± 67	86 ± 47	41 ± 19
Anyang	90 ± 72	180 ± 85	112 ± 30	46 ± 22
Kaifeng	77 ± 56	147 ± 73	100 ± 60	39. ± 19
Jiaozuo	72 ± 48	131 ± 63	84 ± 43	50 ± 20
Xinxiang	64 ± 44	118 ± 60	74 ± 27	40. ± 17
Hebi	76 ± 55	143 ± 72	90 ± 28	45 ± 17
Puyang	80 ± 56	150 ± 51	102 ± 43	42 ± 20