Particles smaller than 2.5 μm in size and diameter of particulate matter (PM2.5) are known to be associated with several cancers, lung and cardiovascular disease, cognitive, hormonal and reproductive disorders. The present study investigated the effect of PM2.5 exposure on the expression level and methylation of the transcription factors EGR1 and EGR2 and the well-known proto-oncogene P53 in lung tissue of rat model of air pollution exposure.48 adult Wistar albino rats (190±35 g) were classified into three treatment and control groups. The current study results were showed a significantly low expression of EGR-1, EGR-2, and P53 in both exposure groups (exposure 1 and 2) compared with the control group. Also, significant down expression of EGR-1 and EGR-2 in group exposure one was revealed versus group exposure 2. MS-HRM assays detected hypermethylation of exposure one and exposure two groups compared to control in six months (for EGR-1, EGR-2, and P53). Our findings revealed that PM2.5 exposure could provoke downregulation and hyper-methylation on transcription factors and proto-oncogenes that, in turn, may alter the expression level and function of several essential genes downstream of molecular pathways. PM2.5 exposure could potentially accelerate several respiratory diseases and cancers and should be considered as a health concern.