(b) Changes in liver IL-6 and TNF-α gene expression in rats ($\stackrel{\circledR }{x}\pm s$)

	IL-6	TNF-α
Control group	0.982 ± 0.231	1.009 ± 0.158
0.75 mg/kg PM2.5 group	1.009 ± 0.202	0.986 ± 0.166
2.5 mg/kg PM2.5 group	1.185 ± 0.243	1.333 ± 0.208ab
5 mg/kg PM2.5 group	1.641 ± 0.207abc	1.714 ± 0.259abc
10 mg/kg PM2.5 group	2.048 ± 0.172abcd	2.128 ± 0.199abcd
F	23.527	29.364
p	<0.001	<0.001

Note: compared to the control group, ^ap < 0.05; compared to the 0.75 mg/kg PM2.5 group, ^bp < 0.05; compared to the 2.5 mg/kg PM2.5 group, ^cp < 0.05; compared to the 5 mg/kg PM2.5 group, ^dp < 0.05.