Final answer:
When working on Compressed Natural Gas (CNG) vehicles, safety considerations include the risk of explosions, exposure to toxic gases like carbon monoxide, and handling fuels that may emit volatile hydrocarbons.
Step-by-step explanation:
The human health hazards that must be considered when working on Compressed Natural Gas (CNG) vehicles include the risk of explosion, exposure to toxic gases such as carbon monoxide (CO), and the handling of fuels that may release volatile hydrocarbons. CNG, like any other fuel, poses risks during storage and combustion. Proper safety measures and equipment are necessary to protect against these hazards. In addition to the aforementioned risks, CNG vehicle maintenance may require exposure to various chemicals and substances used in the automotive industry, some of which could be harmful if proper precautions are not taken.