Carbon monoxide competes with oxygen for binding sites on the transport protien hemoglobin. CO can be poisonous if inhaled in large quantities. A safe level of CO in air is 50 ppm. When the CO level increases to 800ppm, dizziness, nausea, and unconsciousness occur, followed by death. Assuming the partial pressure of oxygen in air at sea level is 0.20atm, what proportion of CO to O2 is fatal?