A method for evaluating microbial contamination of an object, comprising the steps of: (a) incubating a sample taken from the object starting at time t o, (b) periodically ascertaining an O 2 concentration of the incubating sample until the detected O 2 concentration decreases below a threshold value, (c) establishing the time period t Threshold measured from t o to the time at which the O 2 concentration decreased below the threshold value, and (d) correlating t Treshold to a viable aerobic microbe count in the sample prior to incubation, utilizing the linear equation: y = mx + b wherein: x = logarithm of the viable aerobic microbe count per unit weight of, volume of or area swabbed to obtain a sample at t o y = t Threshold x-intercept = (-b/m) = an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at t o in a sample effective for causing the sample to reach t Threshold substantially instantaneously upon commencement of incubation, and m (slope) = (y 2 = y 1)/(x 2 - x 1), wherein: x1, y1, x2 and y2 are values from two and only two data points (x1,y1 and x2,y2), with x 2 and y 2 are values of x and y at the x-intercept (-b/m, 0); and x 1 and y 1 are ascertained experimentally by establishing t Threshold for a sample taken from an object having a known x, wherein x 1 is a viable aerobic microbe count at to which is several orders of magnitude smaller than to at the x-intercept. (a) incubating a sample taken from the object starting at time t o, (b) periodically ascertaining an O 2 concentration of the incubating sample until the detected O 2 concentration decreases below a threshold value, (c) establishing the time period t Threshold measured from t o to the time at which the O 2 concentration decreased below the threshold value, and (d) correlating t Treshold to a viable aerobic microbe count in the sample prior to incubation, utilizing the linear equation: y = mx + b wherein: x = logarithm of the viable aerobic microbe count per unit weight of, volume of or area swabbed to obtain a sample at t o y = t Threshold x-intercept = (-b/m) = an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at t o in a sample effective for causing the sample to reach t Threshold substantially instantaneously upon commencement of incubation, and m (slope) = (y 2 = y 1)/(x 2 - x 1), wherein: x1, y1, x2 and y2 are values from two and only two data points (x1,y1 and x2,y2), with x 2 and y 2 are values of x and y at the x-intercept (-b/m, 0); and x 1 and y 1 are ascertained experimentally by establishing t Threshold for a sample taken from an object having a known x, wherein x 1 is a viable aerobic microbe count at to which is several orders of magnitude smaller than to at the x-intercept. x = logarithm of the viable aerobic microbe count per unit weight of, volume of or area swabbed to obtain a sample at t o y = t Threshold x-intercept = (-b/m) = an estimated or experimental value for the logarithm of the minimum viable aerobic microbe count at t o in a sample effective for causing the sample to reach t Threshold substantially instantaneously upon commencement of incubation, and m (slope) = (y 2 = y 1)/(x 2 - x 1), wherein: x1, y1, x2 and y2 are values from two and only two data points (x1,y1 and x2,y2), with x 2 and y 2 are values of x and y at the x-intercept (-b/m, 0); and x 1 and y 1 are ascertained experimentally by establishing t Threshold for a sample taken from an object having a known x, wherein x 1 is a viable aerobic microbe count at to which is several orders of magnitude smaller than to at the x-intercept.