A system for measuring a gas concentration, the system including: a first oscillator including a first surface for placement in a sampling location, wherein the first oscillator oscillates at a frequency greater than 20,000 Hz but less than 300,000,000 Hz； a first counter to accumulate a count of oscillations of the first oscillator； and a comparator to calculate a difference between the accumulated counts of the first oscillator and a reference, wherein the difference calculated by the comparator is sampled at a frequency of less than 100 Hz.
