Section 307 establishes Group H occupancies for buildings or portions thereof in which hazardous materials are produced, processed, stored, or used in sufficient quantities that they could produce a significant fire, explosion, or toxic gas hazard. Group H is subdivided into H-1 (Explosives), H-2 (Flammable gases and volatile flammable liquids), H-3 (Flammable and combustible liquids), H-4 (Oxidizing gases), H-5 (Gases and liquids that are toxic or produce toxic fumes), and H-6 (Solid hazardous materials). Group H-1 occupancies handle explosives and pyrotechnic materials with the most stringent requirements including extensive separations from other occupancies and isolation from public areas. H-2 occupancies involve storage or use of flammable gases such as hydrogen, propane, and liquefied natural gas, requiring specialized ventilation and monitoring systems. H-3 occupancies include paint shops, solvent storage, and fuel distribution facilities. H-4 occupancies handle oxidizing gases like chlorine and oxygen. H-5 occupancies process toxic substances requiring specialized containment and ventilation. H-6 occupancies handle solid hazardous materials in powder or granular form. All hazardous occupancies require automatic sprinkler protection, specialized ventilation systems, containment for spills and discharges, and emergency monitoring systems. Buildings cannot exceed specific heights and floor areas based on hazard level. Separations from other occupancies range from 2-hour to 4-hour fire-resistance ratings depending on hazard classification. Emergency eyewash stations, showers, and medical response capabilities must be provided.