Burning wood can release small, possibly harmful things into the air. Different wood types, how hot they burn, and what's on them can affect how bad it is. Some woods, like creosote, can even be dangerous when burned. Air quality can get worse from burning wood, especially if there's not much air circulation. Wood with paint or special stuff can make poisonous fumes, and wood treated with a chemical called chromate copper arsenate should never be burned as it's very harmful. To do better, burn dry wood, avoid painted/treated wood, keep air moving, use good stoves, clean chimneys, and think about safety, air, and health when burning wood.