Polymers, including natural proteins (such as DNA) and artificial materials (such as nylon and polyester), are examples of macromolecules. materials scientist Someone who studies the ways in which the atomic and molecular structure of a material relates to its overall properties.
Emission standards for engines and vehicles, including emission standards for greenhouse gas (GHG) emissions, are established by the US Environmental Protection Agency (EPA).The EPA authority to regulate engine emissionsâand the air quality in generalâis based on the Clean Air Act (CAA), most recently amended in 1990.ther states have a choice to either implement the federal emission standards, or else to adopt California requirements (CAA section 177).
One of CARB's responsibilities is to define vehicle emissions standards. California is the only state permitted to issue emissions standards under the federal Clean Air Act, subject to a waiver from the United States Environmental Protection Agency. Other states may choose to follow CARB or federal standards but may not set their own.