Assessment of the effect of air filtration and ventilation on reduction of exposure to submicrometer particles indoors.

The provision of a healthy and satisfactorily clean indoor environment requires that consideration be given to a range of issues, such as the type of indoor environment, indoor and outdoor sources, indoor activity and others. The selection of relevant measures to achieve the required indoor air quality (IAQ) depends on knowledge and understanding of the mechanisms and parameters affecting the concentration levels indoors. The focus of this work was on assessment of the effect of air filtration and ventilation as the most commonly used remedial actions to reduce exposure to airborne pollutants indoors. A simple one zone mathematical model, developed and validated earlier, was applied to evaluate the effect of various parameters, such as filtration efficiency, filter location, mixing factor, deposition velocity and others, on particle concentrations indoors. The evolution in concentration was conducted for several scenarios assuming different outdoor and indoor air conditions. Indoor concentration has been predicted for a hypothetical building representative of an office type environment, located near a busy road in an urban environment. The model could be applied to any type of building and requires only a limited set of input parameters. It could be concluded that indoor air is governed by outdoor air, with air filtration and ventilation as the most dominant removal mechanisms. The effect of particle losses due to coagulation and surface deposition for the presented conditions was less significant. The filtering of the supply air is most efficient in comparison with the filter located at other locations. The effect of room volume was insignificant.