Acne vulgaris is a sebaceous gland disorder that results in plugged pores and outbreaks of lesions. 

As part of their metabolism process, acne bacteria secrete molecules called chromospheres, which are sensitive to blue light. When acne bacteria grow in their active stage, they produce porphyrin. When the blue light hits the porphyrin, it causes a chemical reaction. The chemical reaction causes a change in producing reactive oxygen, which makes holes in the membranes of the bacteria, killing them and enriching the environment with oxygen.