US EPA proposes Tier 3 emission standards

30 March 2013

The US Environmental Protection Agency (EPA) released its long expected proposal for Tier 3 emission standards for light-duty vehicles. The proposal introduces new emission standards that are closely aligned with the California LEV III standards starting from 2017, and are phased-in through 2025. The proposal also tightens sulfur limits for gasoline.

NMOG+NOx Standards. The proposal introduces fleet-average NMOG+NOx (non-methane organic gases + nitrogen oxides) standards that gradually decline to reach 30 mg/mi (FTP test) and 50 mg/mi (SFTP) for passenger cars and light-duty trucks by 2025.

For heavy-duty pick-ups and vans, the FTP NMOG+NOx standards reach 178 mg/mi for Class 2b vehicles and 451-247 mg/mi for Class 3 vehicles by 2022. Additional NMOG+NOx standards measured over a heavy-duty SFTP are being proposed for the first time. The SFTP standards vary by vehicle class and power-to-weight ratio.

PM Standards. The proposed PM standards are expressed on a per-vehicle basis. For cars and light-duty trucks, the PM standard is 3 mg/mi (FTP) for vehicles of all model years, compared to today's standard of 10 mg/mi. As measured over the US06, the proposed PM standard is 10 mg/mi for lighter vehicles and 20 mg/mi for heavier vehicles.

Proposed PM standards for heavy-duty pick-ups and vans are 8 mg/mi for Class 2b vehicles and 10 mg/mi for Class 3 vehicles (FTP test). PM standards are also proposed for emissions measured over the SFTP with standards levels and duty cycles varying by vehicle class and power-to- weight ratio.

Fuel Standards. The proposed fuel standards would require that federal gasoline contains no more than 10 ppm of sulfur (down from today's 30 ppm) on an annual average basis by January 1, 2017. In addition, EPA is proposing to either maintain the current 80 ppm refinery gate and 95 ppm downstream caps or lower them to 50 and 65 ppm, respectively.

The EPA is also proposing to introduce new, more stringent evaporative emission standards. These include new standards over 2-day and 3-day evaporative emission tests, a new "bleed test" and a new "leak test" and standards.

EPA is proposing to adopt and incorporate by reference current OBD regulations by the California ARB, effective for MY 2017, that would cover all vehicles except those in the heavier fraction of the heavy- duty vehicle class.

Source: US EPA