The trick probably works, but the body doesn't actually have a "low-O2" detector, but rather a "high-CO2" detector. Most of the time, they are equivalent; howev

The trick probably works, but the body doesn't actually have a "low-O2" detector, but rather a "high-CO2" detector. Most of the time, they are equivalent; however, if you have e.g. CO poisoning (thus, no CO2 buildup), you don't feel suffocating even though you're out of oxygen.