EPA releases draft Tier 2 study

23 April 1998

The US Environmental Protection Agency (EPA) released draft Tier 2 Study. The EPA concludes in the study that further emission reductions, beyond those provided by the Tier 1 standards, are needed.

According to the study, over 100 million people in the US live in areas that do not meet the health-based ground level ozone standard EPA adopted last year and despite the great success in reducing pollution from cars, motor vehicles remain a major source of the pollution problem. EPA found that significant additional cost-effective reductions are possible and cited the advances in catalyst technology as a key to achieving very low levels of pollution.

EPA stated that while current cars are almost 97% cleaner than 1970 models, emissions from mobile sources still contribute approximately half of the ozone forming pollution affecting nearly 40% of the US population. A major reason is that the vehicle miles traveled since 1970 have increased dramatically and they are expected to continue to grow at an annual rate of two percent a year. Also, sport-utility vehicles, mini-vans, and pick-up trucks, which typically pollute more than cars, now make up nearly 50% of the new passenger vehicles sold.

The Clean Air Act Amendments of 1990 set specific exhaust emission standards, beginning with the 1994 model year, for light duty vehicles (LDVs), or passenger cars, and light duty trucks (LDTs), which include sport utility vehicles, minivans and pick-up trucks. These are "Tier 1 standards." The Act required EPA to study whether further reductions in emissions from these vehicles should be required ("Tier 2 standards") which could not take effect before the 2004 model year.

EPA plans to issue the final report to Congress by 31 July 1998 and to propose new, Tier 2 standards for passenger cars and light-duty trucks in December 1998.

Tier 2 Study [170k, pdf]