Expedient sheltering involves the use of common materials to enhance the safety of a room inside a building against the impact of a chemical plume. The central premise behind taping and sealing with duct tape and plastic is to reduce airflow into a room. Expedient sheltering provides additional protection to people sheltering in place beyond that provided by the house and by a safe room without expedient measures. The materials chosen for taping and sealing - duct tape and plastic - are appropriate because they effectively reduce infiltration and the materials should withstand a vapor challenge. Taping is essential to reduce air infiltration. Plastic sheeting is not a critical element for reducing air infiltration, but it makes sealing off large windows easier. The weakest link in this procedure is the edges of the seals and not the materials used. Duct tape studied for expedient protection against chemical warfare agent simulants was 10 mil (0.01 in.) thickness. It was subject to liquid challenges by the simulants DIMP, DMMP, MAL, and DBS. Plastic (polyethylene) sheeting tested was 2.5, 4, 10, and 20 mil (0.0025, 0.004, 0.01, and 0.02 inches). Figures, table, references