The U.S. Environmental Protection Agency satisfied a prerequisite to finalizing its proposed greenhouse-gas emission standards for light-duty vehicles on Dec. 7, 2009, when administrator Lisa Jackson signed two distinct findings regarding greenhouse gases:
- Endangerment Finding: Concentrations of the six key well-mixed greenhouse gases — carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) — in the atmosphere threaten public health and welfare of current and future generations.
- Cause or Contribute Finding: Combined emissions of these well-mixed greenhouse gases from new motor vehicles and new motor vehicle engines contribute to the greenhouse gas pollution which threatens public health and welfare.
The proposed greenhouse gas emission standards for new light-duty vehicles, issued jointly by EPA and the Department of Transportation's National Highway Safety Administration, would require model-year 2016 vehicles to meet a combined average emissions level of 250 grams of carbon dioxide per mile.
If all the necessary reductions were made through fuel economy improvements, the overall light-duty vehicle fleet would reach 35.5 miles per gallon.
Proposed emissions standards must be finalized by March 31, 2010, so that CAFE regulations are in place the required 18 months prior to the start of production of model year 2012 vehicles (as required by the Energy Policy and Conservation Act).