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摘要

A method and apparatus for determining the alcohol concentration in the blood of a person by testing the person's breath, including, maintaining at least a minimum flow rate for the person's breath to form a test sample of the breath, measuring the alcohol amount in the test sample, measuring the increase in humidity in the test sample over ambient humidity and finding the ratio between the alcohol amount and the increase in humidity. This ratio is proportional to the actual alcohol concentration in the person's blood and cannot be disquised by a person wishing to falsify the results of the test.