Leather: There is no harmful gas when burning itself, but a large amount of aniline dyes, chromium salts and other chemical reagents are used in the processing of leather. During the combustion process, there will be compounds that release nitrogen (nitrogen monoxide, nitrogen dioxide), sulfur dioxide and other harmful substances. Irritating gas, and the dermis is easy to chapped. PU Leather: burning will produce some harmful and irritating plastic gases such as hydrogen cyanide, carbon monoxide, ammonia, nitrogen compounds (nitric oxide, nitrogen dioxide, etc.) PVC Leather: Dioxin and hydrogen chloride are produced in the combustion process and production process. Dioxins and hydrogen chloride are highly toxic substances that can cause cancer and other conditions, and produce a pungent plastic odor. (The main odor comes from solvents, finishing agents, fatliquors, plasticizers and mildew inhibitors, etc.) Silicone Leather: no harmful gas is released, and the burning process is refreshing and odorless.