Biomedical subjects

Jim Lindner

Publications and source records attributed to Jim Lindner.

5 recordsLinked to original sources

PubMed2005

High-mileage study of on-board diagnostic emissions.

The 1990 Clean Air Act amendments require the U.S. Environmental Protection Agency (EPA) to set guidelines for states to follow in designing and running vehicle inspection and maintenance (I/M) programs. Included in this charge was a requirement to implement an on-board diagnostic (OBD) test for both basic and enhanced I/M programs. This paper provides the results to date of an ongoing EPA study undertaken to assess the durability of the OBD system as vehicles age and as mileage is accrued. The primary results of this effort indicate the points described below. First, the majority of high-mileage vehicles tested had emission levels within their certification limits, and their malfunction indicator light (MIL) was not illuminated, indicating that the systems are capable of working throughout the life of a vehicle. Second, OBD provides better air quality benefits than an IM240 test (using the federal test procedure [FTP] as the benchmark comparison). This statement is based on greater emissions reductions from OBD-directed repairs than reductions associated with IM240-identified repairs. In general, the benefits of repairing the OBD fails were smaller, but the aggregate benefits were greater, indicating that OBD tests find both the high-emitting and a number of marginally high-emitting vehicles without false failures that can occur with any tailpipe test. Third, vehicles that truly had high-tailpipe emissions as confirmed by laboratory IM240 and FTP testing also had illuminated MILs at a statistically significant level. Last, field data from state programs have demonstrated MIL illumination rates comparable with those seen in this work, suggesting that the vehicles sampled in this study were representative of the larger fleet. Nonetheless, it is important to continue the testing of high-mileage OBD vehicles into the foreseeable future to ensure that the systems are operating correctly as the fleet ages and as changes in emission certification levels take effect.

Air Pollution↗

PubMed2005

Review of light-duty diesel and heavy-duty diesel gasoline inspection programs.

Emissions from diesel vehicles and gas-powered heavy-duty vehicles are becoming a new focus of many inspection and maintenance (I/M) programs. Diesel particulate matter (PM) is increasingly becoming more recognized as an important health concern, while at the same time, the public awareness of diesel PM emissions because of their visibility have combined to increase the focus on diesel emissions in the United States. This has resulted in an increased interest by some states in including heavy-duty vehicle testing in their I/M program. This paper provides an overview of existing I/M programs focused on testing light-duty diesel vehicles, heavy-duty diesel vehicles, and heavy-duty gasoline vehicles (HDGVs). Information on 39 I/M programs in 27 different states in the United States plus 9 international inspection programs is included. Information on the status of diesel emissions technology and current test procedures is also presented. The goal is to provide useful information for air quality managers as they work to decide whether such I/M programs would be worth pursuing in their respective areas and in evaluating the emissions measurement technology to be used in the program. Testing of HDGVs is generally limited to idle testing, because dynamometer testing of these vehicles is not practical, and most were not certified on a chassis basis. Testing of diesel vehicles has mostly been limited to SAE J1667 "snap-idle" opacity testing. Cost-effective technology for measuring diesel emissions currently does not exist, and, therefore, opacity-type measurements, although not effective at reducing the pollutants of most significant health concern, will continue to be used.

Air Pollutants↗

PubMed2004

Development of the IM147: an alternative inspection/maintenance mass-emission transient test to address vehicle preconditioning concerns.

A series of studies was performed to develop an alternative to the U.S. Environmental Protection Agency's gold standard IM240 mass-based emission test. The new IM147 test was based on the second phase of the IM240 that consists of 147 sec of transient vehicle operation. Paired IM240/IM147 tests were conducted on vehicles ranging from 1981 to 1996 to determine IM147 cutpoints and excess emissions were identified. Additionally, an optimized test procedure was developed that combined possible triplicate IM147s with improved drive trace quality control, fast-pass, and retest methods. The optimized procedure was found to provide improved vehicle preconditioning with a relatively minor decrease in excess emissions identification. Resulting identification rates ranged from 96 to 100% for hydrocarbons (HC), 93-100% for CO, and 93-100% for NOx, depending on cutpoint selection, while false failures caused by lack of vehicle preconditioning were reduced to essentially zero. Significant vehicle throughput improvements were achieved through the development of software algorithms involving modal fast-pass and retest procedures. Modal drive trace variation limits also were developed to improve test accuracy. The combination of the algorithms reduced average IM147 test times by nearly 60%.

Air Pollutants↗

PubMed2003

Inspection/maintenance program evaluation: replicating the Denver Step Method for an Atlanta fleet.

The research presented in this paper employs the Step Method of Inspection/Maintenance (I/M) program evaluation to estimate the emissions reduction for an Atlanta I/M program. Stedman et al. (Stedman, D. H.; Bishop, G. A.; Aldrete, P.; Slott, R. S. Environ. Sci. Technol. 1997, 31, 927-931) introduced the Step Method of evaluation when they presented the results of a 1995 Denver I/M program evaluation. The research presented here replicates the original Denver Step Method analysis for a 1997 Atlanta I/M program. This evaluation was conducted separately for the nine outlying Atlanta counties and the four counties that are closest to the center of the city. The results of the analysis are similar to those found by Stedman et al. in Denver. While the Denver carbon monoxide (CO) weighted program benefit was 6.9%, the Atlanta area CO weighted program benefit is found to be 11.5% and 4.9% for the nine-county and four-county Atlanta areas, respectively. We conclude that the 1997 I/M program change in Atlanta yielded a noteworthy and observable change in fleet emissions.

Carbon Monoxide↗

PubMed2003

Evaluation of a low-cost transient mass measurement system in vehicle inspection and maintenance testing: results of a Gordon-Darby Study.

A study was performed at a Gordon-Darby centralized inspection and maintenance (I/M) test lane in Phoenix, AZ, in December 1999 for the purpose of evaluating the accuracy of production Vehicle Mass Analysis System (VMAS) equipment relative to standard IM240 equipment. Simultaneous transient mass measurements were made on random vehicles using VMAS and IM240 systems on two test lanes during regular I/M testing. Cumulative mass emissions for 846 valid tests were correlated using least-squares regression analysis. Correlation indices were > 0.99 for both carbon monoxide (CO) and nitric oxide (NO) and 0.93 for hydrocarbon (HC), and the standard errors of regression were 1.38 g/mi, 0.123 g/mi, and 0.245 g/mi for CO, NO, and HC, respectively. These strong correlation results are reflected by high excess emission identification rates of 99.4% for CO, 99.3% for NO, and 94.5% for HC when applying final IM240 cut points with a < 2% error of commission for all pollutants.

Air Pollutants↗