Government▼Watch
Whether U.S. trucks and buses are meeting tougher federal emissions standards that go into effect in 2007 should become clearer under a pilot program that analyzes emissions slated to begin in July. Developed by the U.S. EPA, the California Air Resources Board (CARB), and diesel-engine manufacturers, the voluntary two-year program will test emissions from heavy-duty diesel vehicles operating under realworld conditions. The program will become mandatory starting with model year 2007, when EPA’s new tailpipe emission standards for NOx and particulate matter (PM) kick in. Previously, the only way to test engine and vehicle emissions for certification purposes required pulling out the engine and running it through standard cycles on a laboratory dynamometer. But the cycles don’t cover all conditions, and research has shown
PHOTODISC
EPA launches monitoring program for dieselpowered trucks and buses . . .
EPA’s new rule that requires low-sulfur fuels is making it possible to install technologies to clean up tailpipe emissions from diesel trucks and buses.
that operating conditions can strongly affect diesel vehicles’ emission levels (Environ. Sci. Technol. 2004, 38, 152A). Consequently, engine manufacturers had no way of fully ensuring compliance with EPA and CARB standards, which were imposed in 2000 and require emissions to be within a certain range of the limit at all times, regardless of operating
conditions and vehicle age, Suchecki notes. Under the pilot, however, portable emission measurement systems (PEMS), which are about the size of a briefcase, will be attached to selected engines to continuously record exhaust emissions of hydrocarbons, carbon monoxide, NOx, and PM as the vehicle is driven. The process is more accurate and less expensive than the dynamometer, according to Karl Simon, acting assistant director of EPA’s Office of Transportation and Air Quality. “For the first time, we’ll be able to actually look at the in-use, heavy-duty fleet, and this will allow us to see if they comply with the emissions standards that they’re originally certified under,” says CARB’s Michael Carter. EPA and CARB officials plan to use the data to make independent compliance evaluations and to help devise emissions inventories. EPA estimates that the program will cost manufacturers $1.7 million annually. —KRIS CHRISTEN
. . . and California’s big rigs get even more emissions monitoring California is once again getting out ahead of the U.S. EPA. Beginning in 2010, heavy-duty diesel trucks and buses licensed in California will have on-board diagnostic (OBD) systems installed that are similar to those in smaller cars, SUVs, and trucks. The measure, approved by the California Air Resources Board (CARB) in July, is the first in the U.S. and is expected to reduce NOx emissions by about 110 tons per day, “which is a huge, huge deal for us,” says Jerry Martin, a CARB spokesperson. Just under a million heavy-duty diesel trucks and buses currently travel California’s roads. They are responsible for about 28% and 16% of total statewide mobile-source NOx and particulate matter (PM) emissions, respectively. At an estimated cost of $132 per vehicle, each OBD sensor system will monitor 120 different sites in an engine, checking for signs of malfunctioning parts that can increase tailpipe emissions as they age or break down, Martin explains. Once emissions rise to a certain level, a dashboard indicator light is triggered, alerting the vehicle’s operator that part of the pollution control system is failing. An access port under the dashboard allows mechanics using a handheld computer to obtain detailed information about the vehicle’s perfor-
© 2005 American Chemical Society
mance. They can therefore identify the failing equipment so that repairs can be made before the part fails completely. Engine manufacturers worked with CARB to develop the rule, but they still have several key technical concerns related to the feasibility of the PM filter and to the NO x after-treatment monitoring, including the proposed threshold limits, says Joe Suchecki, with the Engine Manufacturers Association. “This is a technology-forcing regulation, and we have significant concerns about its feasibility,” he explains. A similar national program has been successfully operating since 1996 for light- and medium-duty cars, SUVs, and trucks. Because of the high sulfur content of diesel fuels, diesel-pollution-control technologies have lagged 10–20 years behind those for gasoline-powered engines, Martin notes. But a federal low-sulfur-fuel rule that takes effect in January will allow the introduction of PM traps and NO x catalyst equipment in diesel engines, he says. EPA worked with CARB in developing the OBD rule and expects to propose a similar rule for the remaining 49 states sometime this year, says EPA’s Tanya Meekins. A similar requirement will go into effect in the EU in October. —KRIS CHRISTEN
SEP TEMBER 1, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY ■ 361A
