NOVELTY - Determining the dew point in a less expensive manner.    USE - For calculating a dew point.    ADVANTAGE - The inventive method determines the dew point in a less expensive manner.    DETAILED DESCRIPTION - Calculation of a dew point includes providing a signal representative of relative humidity of an ambient; calculating a temperature signal representative of a predetermined dew point; providing a signal representative of actual temperature of the ambient; determining the difference between the signal representative of actual temperature and the calculated temperature signal to provide a differential temperature; using the relative humidity signal, calculating the rate at which dew point changes as a function of temperature; and calculating dew point by multiplying the differential temperature by the calculated rate at which the dew point changes as a function of temperature.    INDEPENDENT CLAIMS are also included for:    (a) a metal-oxide semiconductor (MOS) gas sensor system, comprising a humidity sensor which, in operation, provides a signal representative of relative humidity of the ambient; circuitry configured to calculate a temperature signal representative of a predetermined dew point; a temperature sensor which, in operation, provides a signal representative of temperature of the ambient; circuitry which, in operation, determines the difference between the calculated temperature signal and the signal representative of the temperature of the ambient to provide a differential temperature; circuitry which, in operation, using the relative humidity signal, calculates the rate at which the dew point changes as a function of temperature; dew point calculation circuitry which, in operation, calculates the dew point by multiplying the differential temperature by the calculated rate at which the dew point changes as a function of temperature; and compensation circuitry coupled to the dew point calculation circuitry and configured to modify the signal from the MOS gas sensor, using the calculated dew point, to simultaneously compensate for the effects of both temperature and relative humidity on the MOS gas sensor;    (b) a fuel cell system, comprising a housing having a fuel gas inlet and an exhaust outlet; ion exchange fuel cell membrane located within the housing; and the MOS gas sensor system; and    (c) a method of compensating a MOS gas sensor for environmental dependencies, where the MOS gas sensor has a transfer function that is linear when viewed on a log10-log10 plot of a signal representative of the sensor's output versus gas concentration, and where the transfer function has a slope representing raw gain and has a raw offset, comprising taking the raw offset and gain of the sensor's transfer function, and generating a first signal by normalizing the raw offset and gain to fit a predetermined transfer function at a predetermined dew point, and where the sensor's first signal's gain is scaled on a log10 basis; taking a second signal, which is a function of the dew point of the gas which the MOS gas sensor is configured to sense, and where the influence of the second signal on the first signal is null at the predetermined dew point; and summing the first and second signals to offset the first signal upwards or downwards as viewed on a log10-log10 plot.    DESCRIPTION OF DRAWING(S) - The figure is a perspective, exploded, side elevation view of an ion exchange membrane fuel cell module.    Forward peripheral edge (22)    Apertures (31)    Electrically conductive members (70)    Cathode current collector (60)    Fuel cell module (11)    Dielectric support member (20)    Handle assembly (190)    Back plate (191)    Front surface (192)    Fastening apertures (196)    Current conductor assembly (80)    Fasteners (197)    Member for receiving fastener (84)