Tobacco smoking has become one of the greatest sources of indoor inhalable particles. Tobacco smoke changes chemically and physically after it is released into indoor air, that these changes can increase secondhand smoke (SHS) toxicity. The secondhand smoke (SHS) as assessed by indoor particulate matter with an aerodynamic diameter of less than 2.5 mm (PM2.5) was investigated experimentally and computationally. Test house experiment was performed to study the PM2.5 concentration under controlled conditions coupled with mathematical model of continuity equation. PM2.5 was measured using a DustTrak personal sampler. Two-dimensional flow and dispersion of cigarette smoke were modeled using computational fluids dynamics model (CFD) which were solved using Reynolds-averaged Navier-Stokes equations. The affect of air purifier in reducing secondhand smoke (SHS) and Thirdhand smoke (THS) were analyzed and evaluated. The results demonstrated that the air purifier can't control the indoor PM2.5 levels. Furthermore, amount of smoke from main stream of SHS is more compared to side stream and THS can be evaluated by calculating the adsorption term of continuity equation.