How is hazardous waste typically generated?

Hazardous waste is primarily generated after the use of substances in manufacturing activities because manufacturing processes often involve the use of raw materials, chemicals, and other substances that can become hazardous when they are no longer needed. These substances can include solvents, heavy metals, and other toxic compounds used in the production of goods. Once these materials are utilized, any leftover residues, contaminated materials, or byproducts that no longer serve a useful purpose are classified as hazardous waste if they exhibit characteristics like ignitability, corrosivity, reactivity, or toxicity.

In the context of the other options, while recycling processes can lead to some hazardous materials if not carefully managed, they are typically aimed at reducing waste rather than generating it. The transportation of goods can involve hazardous materials, but it does not inherently create waste; it is more about the movement of materials. Cleaning operations might generate waste, but this waste is often more related to maintenance activities than the significant byproducts produced during the core processes of manufacturing where hazardous waste is predominantly generated.