Body odor

One can measure changes in health and certainly dietary habits by the changes in body odor. This could be a simple way for an agent, perhaps at a residential care facility, to automatically monitor someone who needs care. One could design a shower-head which initially sucks in air for a second, that is, "takes a sniff", has a bunch of sensors which might tell you or your care provider if you haven't been getting enough vitamins or something, and then proceeds to dispense water like a normal shower head. Assuming people take showers at a regular time (this can be checked with a clock) it serves as a relatively constant reference to which delta changes can be measured day-to-day.