The correct procedure is to manually stop the siren by pressing the alarm button on the smoke sensor and then ventilate the room. The alarm is then deactivated for ten minutes. If it still detects smoke after ten minutes, the siren will go off again. If you have several smoke sensors in your home, they will all stop making a sound when you press the alarm button.
From the time the alarm goes off at your place, you have 2 minutes to turn it off before it goes off in the whole building.