Answer: Biomass
Biomass produces gas or many sorts of waste products which are mostly used in burning and cooking. It is plant or animal material used as fuel to produce electricity or heat. Examples are wood, energy crops, and waste from forests, yards, or farms.
But the reason why it can be harmful is because biomass can produce gases like methane. Methane is a greenhouse gas which can harm the environment and reduce the ozone layer that stops harmful UV light from reaching the earth atmosphere.