Why does natural gas have an odor?

Why does natural gas have an odor?

• A. It has an additive (man-made)
• B. Because it is naturally odorless
• C. Because it is heavier than air
• D. Because it is colorless

Answer: (A)

Natural gas would be nearly undetectable by smell on its own, so utilities add a distinctive odorant to make leaks noticeable. The additive is man-made and chosen for a strong, sulfur-like smell (often a mercaptan such as tert-butyl mercaptan or ethanethiol). Even at very low concentrations, people can detect it long before the gas reaches dangerous or explosive levels, providing a safety warning to shut off the supply or evacuate. The gas itself is colorless and odorless, so the odor is introduced deliberately to improve safety; its being heavier or lighter than air is unrelated to why the odor is added.

Natural gas would be nearly undetectable by smell on its own, so utilities add a distinctive odorant to make leaks noticeable. The additive is man-made and chosen for a strong, sulfur-like smell (often a mercaptan such as tert-butyl mercaptan or ethanethiol). Even at very low concentrations, people can detect it long before the gas reaches dangerous or explosive levels, providing a safety warning to shut off the supply or evacuate. The gas itself is colorless and odorless, so the odor is introduced deliberately to improve safety; its being heavier or lighter than air is unrelated to why the odor is added.