An improved ventilating range hood that drives a variable speed fan according
to the state of four distinct air quality sensors: temperature, humidity, Carbon
monoxide and smoke. A micro-controller is used to integrate the four signals and
determine the appropriate ventilation requirement. This value is converted into
a signal to drive the fan. Visual indicators are provided to display the state
of each air quality factor. An audible alarm is activated if the levels remain
at hazardous levels for more than a predetermined time interval after the fan has
been turned on.
