Honorable Rick Boucher

House of Representatives

Washington, D.C. 20515-4609

Dear Mr. Boucher:

Thank you for your December 24, 1991 letter with which you enclosed an article sent to you by one of your constituents, Mr. Jay Stone. Mr. Stone is concerned about the possibility that requirements under the Clean Air Act may place unnecessary burdens on those who make modifications on older vehicles. You asked us to provide you with an analysis of this concern. I have provided a broad discussion of the regulations and policies governing the control of motor vehicle emissions. I think this helps put the "hot rod" car issue into perspective.

We believe that all citizens are responsible for maintaining the emission control systems on their vehicles just as they would safety equipment. Vehicles which have had emission control devices removed can contribute up to five times the amount of pollution to the atmosphere as identical vehicles with the devices and systems properly installed. Federal emissions standards have applied to motor vehicles since 1968.

The Clean Air Act (Act) prohibits anyone from permanently removing or rendering inoperative (tampering with) any emission control device or element of design installed on or in a motor vehicle or motor vehicle engine by the manufacturer in order for that vehicle or engine to meet Federal emission standards.

The Federal tampering prohibition is contained in section 203(a)(3) of the Act, 42 U.S.C. 7522(a)(3). Section 203(a)(3)(A) of the Act prohibits any person from removing or rendering inoperative any emission control device or element of design installed on or in a motor vehicle or motor vehicle engine prior to its sale and delivery to an ultimate purchaser and prohibits any person from knowingly removing or rendering inoperative any such device or element of design after such sale and delivery, and the causing thereof. The maximum civil penalty for a violation of this section by a manufacturer or dealer is $25,000; for any other person, $2,500.

Section 203(a)(3)(B) of the Act prohibits any person from manufacturing or selling, or offering to sell, or installing, any part or component intended for use with, or as part of, any motor vehicle or motor vehicle engine where a principal effect of the part or component is to bypass, defeat, or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine, and where the person knows or should know that such part or component is being offered for sale or is being installed for such use. The maximum civil penalty for a violation of this section is $2,500.

The U.S. Environmental Protection Agency (EPA) has established an enforcement policy which is intended to reduce the uncertainty that named parties, and part manufacturers and suppliers face regarding potential liability under section 203(a)(3) of the Act if they use or sell aftermarket parts or systems, or make adjustments or alterations to parts or system parameters. These guidelines may be used to provide assurance that certain acts do not constitute tampering. This policy is outlined in Mobile Source Enforcement Memorandum No. 1A (copy enclosed). Basically this policy states that we will not consider any modification to a certified emissions control configuration to be a violation of the tampering prohibition if there is a reasonable basis for knowing that emissions are not adversely affected. In many cases, emission testing according to the Federal Test Procedure would be necessary to make this determination.

The specific language of Memorandum No. 1A addresses only dealers and vehicle and engine manufacturers. In 1977 and again in 1990, section 203(a)(3) was amended and the tampering prohibition extended to include any person as well as commercial repair facilities and fleet operators. The policy enunciated in Memorandum No. 1A has been extended to all the parties named in section 203(a)(3) as well as automobile part manufacturers and suppliers.

The EPA does not decide which emission control devices and systems the manufacturers must use to meet Federal emission standards. The manufacturers must certify that their vehicles will meet Federal emission standards for the model year in which they were built, and they design and install the systems and components necessary to meet those standards.

The testing that the manufacturers perform to demonstrate compliance with Federal standards is more comprehensive and accurate than the idle tests used by the Inspection/Maintenance (I/M) programs. For example, the procedures for light-duty cars and trucks require the vehicles to undergo prescribed sequences of fueling, parking, and operating in order to simulate an average trip in an urban area. Heavy-duty engine testing requires a similar transient mode testing procedure. During these procedures, the emissions are sampled continuously over the entire test cycle for subsequent analyses of specific components by prescribed analytical techniques. These procedures are more representative of in-use operation than any state or locally run idle emissions test.

Idle emissions tests used by state I/M programs are designed merely as screening tests for identifying gross emitting vehicles which have not had proper maintenance (spark plug replacements, air filter changes, timing adjustments, carburetion adjustments, etc.), and not to detect whether specific emission control components are present and operational. The tests usually only involve the insertion of a probe into the tail-pipe of the vehicle while the vehicle is idling and instantaneously measuring the exhaust emissions. These tests are not as stringent or accurate as the Federal test procedures and the results are not comparable. It would be inaccurate to assume that just because a vehicle "passes" an idle test that it could also pass Federal standards.

For example, air pumps are often used by vehicle manufacturers to help reduce hydrocarbon (HC) and carbon monoxide (CO) tailpipe emissions. Air injected into the exhaust manifold allows the combustion process to continue as the exhaust leaves the cylinder and enters the manifold and the upper portion of the exhaust system. This continuation of the combustion process reduces the amount of HC and CO present in the exhaust gases. On catalyst equipped vehicles, the air pump supplies additional oxygen to facilitate the chemical reaction that occurs in the catalyst. The air pumped into the exhaust system has no effect on the efficiency of the combustion process in the cylinder since it is injected into the manifold or exhaust system after the process has occurred. In all likelihood, any vehicle that was certified with an air pump would probably fail Federal standards without it unless the entire emission system is redesigned. On the other hand, some such vehicles can be adjusted or "tuned" to "pass" state or local idle test standards.

In order to help bridge the gap between the accuracy of the Federal certification testing and the idle test, many state I/M programs also require that certain emission components be specifically checked for their presence and operation. In order to avoid the confusion created by the misperception that passing an idle test means the vehicle can meet Federal standards, most I/M programs do not perform the idle portion of the test until the vehicle is properly equipped with the components that were originally on the vehicle as it was certified by the manufacturer. We believe that this is appropriate.

Also enclosed is a copy of our policy on engine switching. The policy explains how and under what circumstances engine changes can be performed. Basically, if it can be demonstrated that modifications to a vehicle do not cause the vehicle to exceed emission standards, we would not consider the modification to be illegal. While it is possible to put in other engines in vehicles which make the vehicles different than the way they were certified, often it is not very practical.

I hope we have been responsive to your request. If you have any further questions, please contact me or Ms. Mary T. Smith, Director, Field Operations and Support Division, at (202) 260-2633.

Sincerely,

Wilson

Enclosures

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