Hydrogen sulfide is an inorganic compound, generally gas and colorless. At low concentration, it smells like rotten eggs and is highly toxic. Hydrogen sulfide has a strong neurotoxin and a strong stimulating effect on mucosa. Hydrogen sulfide inhaled by people can cause respiratory tract and eye irritation, and long-term inhalation can cause olfactory nerve paralysis, pulmonary edema, and even death due to respiratory nerve paralysis in severe cases.