Critical Study of the United States Exhaust Emission Certification Test-Error and Probability Analysis

The United States regulations concerning the Automobile exhaust emissions stipulate the limits of the individual pollutants that must not be exceeded, but make no allowance for measuring uncertainties when evaluating the test results; nor are the final results subjected to any form of statistical analysis.

We have performed a critical study of the Exhaust Emission Certification Test based on statistical methods. With the results of this investigation, it is possible to calculate the real risk for passing the Certification Test and to determine the engineering goals (or safety margins) which are required to pass Certification. In addition, systematic errors should be taken into account.

Meeting these safety margins represents an calculable additional aggravation of the already stringent standards.