With the easily operated tension lever the portable smoke blocker made out of heat resistant fabric can be installed quickly into a door or entrance opening. The door to the affected area can be opened now and the fire fighters can enter the room behind for their operations without the spread of smoke and heat in the building. Escape routes for the residents and retreat ways for the fire fighters stay smoke-free. It is possible for the security backup to stay close to the attacking fire fighters. The time for the rescue operation in case of a breathing protection emergency is considerable reduced. Dangerous situations through smoke and heat spread are effectively minimized or avoided. The portable smoke blocker allows controlling the inflow of air to the area of fire for directed and controlled ventilation. Smoke damages can clearly be reduced.