We used 2 of the Biocide Systems "Room Shocker" units rated for "up to 400 square feet of floor space" in a 1500+ square foot finished downstairs apartment. The space was vacated for 48 hours, then windows were opened to ventilate. The very strong chlorine odor persists even after running the furnace fan in addition to the open windows and doors. Instructions were followed to the letter. I have used Biocide products in the past (aerosol) and had excellent results with NO ODOR. Our home continues to smell like a pool house. I would not recommend the "Room Shocker" product at all.