sulfur – n. a yellow chemical element that has a strong, unpleasant odor when it is burned and that is used in making paper, gunpowder, medicine, etc.

emission – n. the act of producing or sending out something (such as energy or gas) from a source

incomplete – adj. not complete

introduce – v. to bring into play; to lead or bring in, usually for the first time

standard – n. something set up as a rule for the measure of quality, amount of value