A smoke detection sensor ion chamber has a capacitance and a change in the permittivity of that capacitance dielectric (ionized air in the chamber) may be used to detect the presence of smoke therein. Smoke from typical fires is mainly composed of unburned carbon that has diffused in the surrounding air and rises with the heat of the fire. The permittivity of the carbon particles is about 10 to 15 times the permittivity of clean air. The addition of the carbon particles into the air in the ion chamber changes in the permittivity thereof that is large enough to measure by measuring a change in capacitance of the ion chamber.