Our major findings include: 1) Inhalation exposure to PM2.5 for 12 weeks (not 6 weeks) can induce ICA as evidenced by MCA thickening and MCA lumen narrowing; 2) HCD induced ICA in rats, and PM2.5 enhanced the HCD-induced atherosclerosis; 3) PM2.5-induced vascular inflammation (the elevated expression of TNF-α, IL-6, MCP-1 and IFN-γ) and vascular dysfunction (the increased expression of VCAM-1 and iNOS) may be the underlying mechanisms for atherosclerosis; 4) Oral supplementation of O3FA for 12 weeks ameliorated the detrimental effects of PM2.5 (as shown in Figure 8). Here, NOS2 is linked to atherosclerosis.