HOW MUCH PROTECTION DOES A BUILDING SHELL PROVIDE AGAINST AIRBORNE AGENTS

摘要

Along with the widespread recognition that most people spend the majority of their time indoors comes increasing interest in the influence of the ambient environment on indoor exposure to hazardous pollutants. With the resurgence of terrorists' activities, comes a keen interest in the degree of protection that a building shell affords against exposure to toxic, biological, and chemical agents. This paper will update the results of an on going study of the influence of building construction features and operating parameters on the entry of paniculate contaminants. This study has recently made significant progress in quantifying the contribution of a number of categories of leaks to both the air exchange rate and particle penetration in an unoccupied house. The degree of protection afforded as a function of particle size is presented for the house operated in both closed and open (open windows) conditions. The effect of window openings on both the air exchange rate and the building protection factor are presented. The contribution of individual categories of leaks (such as openings around electrical outlets, cracks around windows, cracks between gypsum board and plate, and cracks between the plate and floor) to air exchange rate and building protection factor are presented. It is shown that the building shell provides the least protection against particles larger than 0.1 μm and smaller than about 2 μm in aerodynamic diameter. Measured rates of particle deposition on interior surfaces are also shown.