Table 5. Comparison of PM_2.5 chemical composition during the sampling periods.

Sampling Sites	EC/TC	K/TC	NO3-/nss-SO42−	TC/SO42−	Reference
Xiamen	0.3	0.2	0.6	0.9	This study (2015)
Fuzhou	0.3	0.1	0.7	1.2	This study (2015)
Penghu	0.4	0.2	0.5	0.9	This study (2015)
Kaohsiung	0.4	0.1	0.6	0.8	This study (2015)
Taichung	0.4	0.2	0.8	0.9	This study (2015)
Taipei	0.4	0.2	0.7	0.8	This study (2015)
Fuzhou	0.2	0.02	0.4	1.0	Xu et al.80
Xiamen	0.2	0.1	0.5	1.2	Zhang et al.81
Xiamen	0.2	–	0.5	1.2	Zhao et al.82
Qingdao	0.2	0.1	1.0	1.5	Cao et al.2
Hong Kong	0.3	0.04	1.0	0.9	Cao et al.2
Shanghai	0.2	0.04	1.0	1.5	Cao et al.2
Seoul, Korea	0.3	0.03	0.9	1.7	Heo et al.83
Yokohama, Japan	0.3	0.02	1.1	1.5	Khan et al.63
Italy	0.1	–	1.9	2.4	Lonati et al.84