Sulfur dioxide is not produced when you burn a matchstick. When a matchstick is lit, the heat causes the head of the matchstick to ignite and burn. The main components of the matchstick head are potassium chlorate, antimony sulfide, and red phosphorus. When these components come into contact with the heat, they undergo chemical reactions that produce oxygen and heat, which in turn cause the matchstick to burn. Sulfur dioxide is not a product of these reactions.