The present invention relates to a method of determining skin health of an area of skin by exposing the area of skin to a first exposure radiation to induce the area of skin to emit a first fluorescent emission, measuring the intensity of the first fluorescent emission, exposing the area of skin to a second exposure radiation to induce the area of skin to emit a second fluorescent emission, measuring the intensity of the second fluorescent emission, calculating a ratio of these intensities, and comparing the ratio to a control ratio.