Numerical assessment of the effect of cigarette smoking on indoor PM2.5 distribution and study of ventilation strategies

Elevated concentration of indoor particulate matter (PM) has been linked to adverse effects on human health. To explore how particles from cigarette smoke affect the indoor PM2.5 concentration and whether such circumstance is harmful to people, distribution characteristics of indoor particulate matter in a typical residence with a smoker were numerically studied under different ventilation strategies. The indoor PM2.5 concentration without forced ventilation was shown to far exceed the air quality standard of 75 mu g/m(3) as recommended by the World Health Organization. In this study, we numerically investigated the performances of the mixing and displacement ventilation strategies in reducing indoor particle levels. Different airflow patterns could significantly influence the movement and deposition of particles in ventilated rooms, even with the same air change rate and particle characteristics. When comparing with the mixing ventilation strategy, the displacement ventilation strategy was shown to have a lower deposition mass and a larger portion of particles leaving the room. Thus, the average indoor PM2.5 concentration in the displacement ventilation strategy was shown to be higher than the mixing ventilation strategy. In spite of this, low particle concentration in the personnel's breathing zone was shown by our measurement. Displacement ventilation strategy could provide a cleaner ambient air than the mixing one.