Abstract: The present invention provides a product line of precisely fitted, flow-through, hinged metal frames, analogous to exterior shutters, but mounted on the interior of the building, designed to be permanently mounted to windows and sliding-glass doors, and to swing and lock into the opening created when the window or door is opened, allowing the free flow of fresh air and preventing any forced entry or intrusion. The size of the grid-style frame depends on the on the style of window, traditional sliding-sash, casement, etc., or door being fitted. In each case, the Fresh Air Safety Bars frame are double-hinged on one side, and feature a pre-drilled mounting plate, welded or bolted to the hinge assembly. This mounting plate is fastened to the wall immediately adjacent to the window or sliding-glass door. Each Fresh Air Safety Bars unit, once mounted in proper position and alignment with the window or door to be fitted, swings on its hinges to snugly and securely occupy the window or door opening.