=+4-18.

Each person in a room is assumed to be producing carbon dioxide at the average rate of 0.0107 cfm (5.0 ml/s) and air with a CO, concentration of 280 ppm is being supplied to the room at the rate of 6000 cfm (2.8 m /s). It is desired to keep the concentration level of CO, in the space below 1000 ppm. Assuming complete mixing, determine how many persons could occupy the room and not exceed the desired CO, level