COMMONWEALTH OF MASSACHUSETTS

EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS

DEPARTMENT OF ENVIRONMENTAL PROTECTION

ONE WINTER STREET, BOSTON, MA 02108 617-292-5500

DEVAL L. PATRICK

Governor

TIMOTHY P. MURRAY

Lieutenant Governor

IAN A. BOWLES

Secretary

LAURIE BURT

Commissioner

This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at 617-556-1057. TDD Service - 1-800-298-2207.

MassDEP on the World Wide Web: http://www.mass.gov/dep

 Printed on Recycled Paper

MassDEP

Bureau of Waste Prevention

Division of Consumer and Transportation Programs

310 CMR 60.02:

Massachusetts Motor Vehicle Emissions Inspection and 

Maintenance Program

Background Document and Technical Support for Public Hearings on 

the Proposed Amendments to the

State Implementation Plan for Ozone

Regulatory Authority: Massachusetts General Laws, Chapter 111,

Sections 142A through 142M

February 2007

This version was submitted with the Massachusetts SIP 

Revision to 310 CMR 60.02, of the Massachusetts Motor 

Vehicle Emissions Inspection and Maintenance Program;

as Table of Contents Item Six: Final for EPA Submittal
MA SIP Revision: Table of Contents Item 6 – Background and Technical Support for Public Hearings

MA SIP Revision, 310 CMR 60.02, the Massachusetts Motor Vehicle Emissions Inspection and Maintenance Program. 

Documentation of IM SIP Revision consistent with 42 USC Section 7511a and Section 182 (c)(3)(A) of the Clean Air Act 2

TABLE OF CONTENTS

Section Page

I. INTRODUCTION 3

II. SUMMARY OF PROPOSED AMENDMENTS TO 310 CMR 60.02 5

III. KEY ISSUES 10

Emissions Testing Technology: From Idle to Dynamometer to OBD Test 11

Malfunction Indicator Light Bulb Check 12

Discretionary Flexibility for Operational Issues 14

Opacity Emissions Test Cutpoints 15

Emissions Waivers 16

Economic Hardship Failure Repair Extensions 17

Registered Repair Technicians 18

IV. AIR QUALITY IMPACTS 19

V. ECONOMIC IMPACTS 23

Elimination of Dynamometer Tailpipe Testing 23

More Stringent Opacity Test Cutpoints 23

Increase in Emissions Test Frequency 24

APPENDICES

Appendix A - Proposed Amendments to 310 CMR 60.02

Appendix B - Notice of Public Hearing
COMMONWEALTH OF MASSACHUSETTS

EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS

DEPARTMENT OF ENVIRONMENTAL PROTECTION

ONE WINTER STREET, BOSTON, MA 02108 617-292-5500

DEVAL L. PATRICK

Governor

TIMOTHY P. MURRAY

Lieutenant Governor

IAN A. BOWLES

Secretary

LAURIE BURT

Commissioner

This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at 617-556-1057. TDD Service - 1-800-298-2207.

MassDEP on the World Wide Web: http://www.mass.gov/dep

 Printed on Recycled Paper

Background Document and Technical Support For Public Hearing

To Consider Amendments to:

310 CMR 60.02: Massachusetts Motor Vehicle Emissions Inspection and 

Maintenance Program

February 2007

The Massachusetts Department of Environmental Protection (MassDEP) is proposing 

amendments to the Massachusetts Motor Vehicle Emissions Inspection and Maintenance 

Program Regulation, 310 CMR 60.02, and the State Implementation Plan (SIP) for ozone. 

I. INTRODUCTION

Massachusetts’ air exceeds the federal health based standards for ground level ozone. On “bad 

air” days, there are increases in asthma attacks and hospitalizations for people with severe 

respiratory ailments. To reduce the number of “bad air” days and to comply with the Federal 

Clean Air Act and U.S. Environmental Protection Agency (EPA) regulations, Massachusetts 

implements a variety of federally mandated programs, which are collectively known as the “State 

Implementation Plan” or “SIP”.1 

The most recent inventory of sources of ozone causing pollutants (volatile organic compounds 

and nitrogen oxides) in Massachusetts2indicates that motor vehicles operated on roads (“on-road 

vehicles”) contribute approximately 37% of those pollutants. To reduce pollution from motor 

vehicles, EPA requires Massachusetts to operate an Enhanced Inspection and Maintenance 

(I&M) program. EPA sets performance standards for I&M programs3.

 

1 These programs are established in legally binding and federally enforceable “State Implementation Plans” or 

“SIPs”.

2 Massachusetts 2002 Baseline Emission Inventory of Volatile Organic Compounds and Nitrogen Oxides, June 2006. 

http://www.mass.gov/dep/air/priorities/s1dintro.pdf

3

40 CFR Part 51, Subpart S (§51.350 et seq.). 
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The Massachusetts Department of Environmental Protection (“MassDEP”) and the 

Massachusetts Registry of Motor Vehicles (“RMV”) jointly administer the I&M program. The 

I&M Program is designed to reduce ozone pollution and achieve and maintain clean air, and to 

ensure that motor vehicles that are operated in the Commonwealth are safe. The current 

Massachusetts I&M program was authorized by the Legislature by Chapter 210 of the Acts of 

1997. Implementing regulations (310 CMR 60.02) were initially adopted in January 1999. 

Since 1999, the program has been implemented through a contract with Applus Technologies, 

Inc.4

The I&M program, as established in 1999, has four goals: 

 To reduce vehicle pollution; 

 To identify unsafe vehicles; 

 To ensure that the program is convenient and reasonably priced for the public; and 

 To promote effective repairs by designing the program to fit well with the repair industry. 

There are approximately 4.6 million vehicles registered in Massachusetts. Under the current 

regulations, all are required to obtain an annual safety inspection, and the vast majority of 

vehicles receive an emissions test every other year. Vehicles currently exempt from emissions 

testing are: 

 Model year 1984 or older; 

 Less than 2 years old and still registered to the original owner; or

 Light and medium duty diesel fueled vehicles. 

Since 1999, the program has relied on a decentralized network of inspection stations that are 

licensed by RMV to conduct safety and emissions tests. Most Massachusetts vehicles receive 

their inspections at local public stations. The program also allows owners of vehicle fleets to 

purchase testing equipment so they can test their own vehicles. In 2006, 1,674 stations 

conducted inspections: 1,565 were public stations and 109 were fleet only stations.

The current contract will expire on September 30, 2008, and the Agencies are now reviewing 

bids solicited through a competitive process for a new contract. MassDEP is proposing to amend 

its I&M regulations to update the program and to comply with federal requirements that have 

been enacted since the regulations were last amended. At the same time, RMV is proposing to 

amend its regulations (540 CMR 4.00-4.09). The Agencies will seek public comment jointly. 

Also, prior to October 1, 2008, the Executive Office of Administration and Finance may propose 

regulations that would revise the fee that motorists pay for inspections, following the 

promulgation of MassDEP and RMV revised regulations and the execution of a new contract. 

Vehicle testing under the new contract will begin on October 1, 2008. 

Under the proposed regulations, the I&M program will continue to deliver inspections through a 

decentralized network of local inspection stations. All vehicles will continue to receive an 

annual safety inspection. However, the amendments propose to require an annual emissions test, 

 

4 The Contractor was originally known as “Keating Technologies, Inc.” In July 2001, the Contractor changed its 

name to “Agbar Technologies, Inc.”(due to a corporate buy-out), and in February 2005, changed its name again to 

“Applus Technologies, Inc”. 
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rather than the biennial test in the current program. The emissions test would rely primarily on 

an “on-board diagnostic” (OBD) test; the current program’s use of a dynamometer to test tailpipe 

emissions would be discontinued. Large diesel trucks and buses not equipped with an OBD 

system would continue to receive an opacity test; the amendments propose to lower the opacity 

cut points for these vehicles. As new medium- and heavy-duty vehicles become equipped with 

OBD systems, they would also be required to obtain an annual OBD emissions test.

This document summarizes the proposed amendments to 310 CMR 60.02, and describes key

issues on which MassDEP seeks public comment. It also describes the impact of these 

regulation (and program) changes on air quality and the Commonwealth’s economy. The 

proposed amendments can be found in Appendix A. 

As required by M.G.L. c. 111, Section 142K and M.G.L. c. 30A, MassDEP seeks public 

comment on these proposals. Information about public hearings and how to submit written 

comment can be found in the Notice of Public Hearing in Appendix B. This public comment 

period has also been designed to comply with EPA’s requirements for revisions of State 

Implementation Plans. 

II. SUMMARY OF PROPOSED AMENDMENTS TO 310 CMR 60.02

The I&M regulation is proposed to be modified as follows. The amendments that are consistent 

with the new I&M program contract would take effect on October 1, 2008.

OBD Emissions Testing

 Tailpipe testing requirements for most vehicles that are not equipped with OBD would be 

deleted. 

 Most OBD-equipped vehicles in Massachusetts would receive an annual emissions test 

instead of a biennial test.

 The vehicles described in Table 1 below would be subject to an OBD emissions test. 
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Table 1

Vehicles That Would Receive an OBD Emissions Test

Vehicle Fuel Gross Vehicle Weight Rating 

(GVWR)

OBD Testing Starting 

with Model Year

Non-diesel Light duty: 8,500 pounds or 

less

1996

Diesel Light duty: 8,500 pounds or 

less

1997

Non-diesel Medium duty: greater than 

8,500 and less than or equal to 

14,000 pounds

2008

Diesel Medium duty: greater than 

8,500 and less than or equal to 

14,000 pounds

2007

All Heavy duty: greater than 

14,000 pounds

Phased in as OBD 

systems are required to 

be installed, starting with 

model year 2010 

 OBD-equipped vehicles would be exempt when they are 15 years old (a rolling 15-year 

exemption). 

 Vehicles that fail the emissions test because the malfunction indicator light (MIL) on the 

dashboard is commanded on by the OBD system would be checked to make sure it is 

functioning.

 When an emissions inspection indicates that a vehicle’s emission control system has been 

tampered with or otherwise altered so that a complete test cannot be performed, the motorist 

would be required to present his or her vehicle to a location designated by the Agencies to 

resolve the issue. For example, a mismatch between the Vehicle Identification Number 

(VIN) and the OBD VIN indicates that the vehicle’s emission control system may have been 

tampered with.

New Vehicles Equipped with OBD

 The two year exemption from emissions inspection currently provided for new vehicles 

would be eliminated. 

 New vehicles would receive an advisory computer scan of their OBD systems as part of 

the inspection required for the vehicles’ first registration. This scan would not be an 

emissions test, but it would provide an electronic “fingerprint” of the vehicle for future 

use by the Agencies in detecting tampering with vehicles’ emission control systems and 

preventing fraudulent inspections. 
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 The scan would verify that the OBD system is operating properly, and would advise the 

dealer and the buyer if it finds a fundamental flaw (e.g. the on-board computer is not 

performing the required checks on the vehicle or will not communicate with OBD test 

equipment, or the vehicle’s VIN and OBD VIN do not match). If a fundamental flaw is 

identified but not fixed before the vehicle has its first emissions test, the vehicle would 

fail its inspection. New car dealers authorized by RMV to use their pre-delivery

inspection as a safety inspection would be allowed to perform this scan before a vehicle 

is delivered. 

Emissions Tests for Medium and Heavy Duty Diesel Trucks and Buses Not Equipped with OBD

 Opacity testing requirements would be retained for heavy-duty diesel vehicles and 

medium duty diesel vehicles more than 10,000 pounds GVWR that are model year 1984 

and newer and that do not have OBD systems.

 The diesel opacity cutpoints for the opacity test would be tightened, as described in 

Table 2. 

Table 2

Proposed Opacity Test Cutpoints

For Diesel Trucks and Buses greater than 10,000 pounds GVWR

Current 

Cutpoints

Cutpoints

Beginning 

October 1, 2008

Percent Opacity Percent Opacity

Diesel trucks greater than 10,000 pounds GVWR

1984 – 1990 model years 55% 40%

1991 – 1996 model years 40% 30%

1997 and newer model years 40% 20%

Diesel buses greater than 10,000 pounds GVWR

1984 – 1987 model years 40% 40%

1988 – 1993 model years 40% 30%

1994 and newer model years 30% 20%

Emissions Tests for Other/Specialty Vehicles

 Glider kits (vehicles weighing more than 10,000 pounds with a different vehicle body 

placed upon the original chassis) would be required to have a visual inspection when they

are first registered, to verify that they were assembled consistently with their 

configuration certified by EPA or the California Air Resources Board (CARB). Some 

glider kits may be subject to an opacity test, based on the model year of the chassis. 

 Kit vehicles (unique or replica vehicles with production volume less than 500 vehicles 

per year) would be required to have a visual inspection when they are first registered and 
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upon change of ownership to verify that they comply with applicable emission control 

requirements. This is consistent with EPA’s policy on kit vehicles5. A list of the 

documentation that must be provided for the kit vehicle visual inspection will be posted 

on the Enhanced Emissions and Safety Test Program web site.

 Provisions governing engine-switching would be revised to reflect EPA requirements, to 

ensure that replacement engines are appropriate for the vehicle in which they are installed 

and maintain the vehicle’s low emissions characteristics. 

 Definitions and other provisions would be revised to address assembled and 

reconstructed vehicles, gray market vehicles, specialty import vehicles, and vehicles that 

have been issued exemptions by EPA or CARB.

Waivers from Emission Standards

 The expenditure thresholds for waiver eligibility would be increased, based on increases 

in the Consumer Price Index since the thresholds were originally established (on the basis 

of 1989 dollars). Cost thresholds for waivers would still be based on the age of the 

vehicle, and would be used to consider a vehicle for a waiver when repair costs exceed: 

o $750 for vehicles five model years old or newer;

o $650 for vehicles six to ten model years old; and

o $550 for vehicles more than ten model years old.

 The new waiver expenditure thresholds would be adjusted annually, based on the changes 

in the Consumer Price Index, starting in 2010.

 Eligibility criteria would be updated to reflect factors that the program has been using 

informally to determine waiver eligibility for OBD equipped vehicles since full-scale 

OBD testing started in 2004. Waivers would only be available for vehicles that: 

o Failed their initial inspection, were repaired, and failed their re-inspection;

o Have not failed their reinspection for problems that would cause the vehicle to be 

a gross emitter (catalytic converter efficiency, misfire, diesel particulate filter or 

energy storage in hybrid vehicles);

o Are registered as a private passenger motor vehicle or auto home (no waivers for 

commercial vehicles);

o Meet all safety requirements;

o Show no evidence that the emissions control system has been tampered with;

o Have a properly functioning malfunction indicator light;

o Have had repairs performed by a registered repair technician that are appropriate 

to the diagnostic trouble codes that caused the failure;

o Have used all relevant manufacturer related warranties and recalls; and

o Have repair costs that exceeded the thresholds described above.

 Costs associated with the following repairs would be ineligible for consideration towards 

the waiver cost limit:

 

5 EPA Kit Car Policy, June 8, 1994. http://www.epa.gov/otaq/imports/kitcar.htm
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o Correcting an improper engine switch or replacement;

o Correcting tampering;

o Returning the malfunction indicator light to proper operation;

o Meeting the minimum test criteria for readiness (to ensure that the OBD computer 

is running its required checks of vehicle systems); however, for repairs requiring 

replacement of the power train control module (i.e., the on-board computer), a 

motorist will be allowed to combine one half of the replacement cost of the 

module with the cost of repairs needed to resolve diagnostic trouble codes to meet 

the applicable waiver expenditure limit; and

o Any repairs not performed by a registered repair technician, except where 

MassDEP has specified that certain specialty repairs may be performed by a nonregistered repairer.

 The diagnostic waiver provision would be deleted, since this only applies to tailpipe tests. 

This deletion would take effect on October 1, 2008, when the tailpipe test would be 

discontinued.

Economic Hardship Failure Repair Extension

 An Economic Hardship Repair Extension would allow a one year extension of the 

requirement to pass an emissions test, for non-commercial OBD vehicles that:

o Have failed their re-inspection;

o Have no safety failures;

o Have an emissions control system that shows no evidence of tampering;

o Have an estimate of emissions-related repair work from a registered repair 

technician that MassDEP agrees is reasonable and is more than 1.5 times the 

applicable waiver repair expenditure threshold;

o Have exhausted all warranty coverage including recalls; and

o Do not qualify for a waiver.

 The extension would be valid until the vehicle’s next emissions inspection, and would not 

be eligible for renewal. A vehicle receiving an economic hardship repair extension 

would be required to pass its next emissions test. 

 No economic hardship extensions would be given for inspections associated with a 

change of ownership.

Registered Repairers

 The registered repairer technician eligibility would be expanded to include certifications 

for certain types of vehicles, such as: 

o Specific fuels (e.g., diesel); or

o Specific engines, vehicle makes or models at a manufacturer’s repair facility or 

dealership at which the registered repairer is employed. 

 MassDEP would be authorized to remove repairers from the list of registered repair 

technicians if the repairer: 

o Does not maintain the requirements for qualification;
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o Provides false documentation of a repair or repair costs to the Agencies; or 

o Has been determined to have been a party to deceptive or fraudulent business 

practices related to emissions control system repairs or to environmental 

protection.

 In addition to its current practice of removing repair shops that no longer employ a 

registered repair technician from the program’s list of registered repair facilities, 

MassDEP would also be authorized to remove repair shops from the list of registered 

repair facilities if the repair shop: 

o Provides false documentation of a repair or repair costs to the Agencies; or 

o Has been determined to have been a party to deceptive or fraudulent business 

practices related to the repair of emission control systems or environmental 

protection. 

General

 I&M requirements that are currently in effect would remain so through September 30, 

2008. 

 New requirements proposed in this package (which are consistent with the new I&M 

program contract) would take effect on October 1, 2008. 

 Minor edits would align the regulations with current program practices, such as: 

o Allowing vehicles that have been granted an emission control system waiver or 

exemption by the certifying agency (EPA or CARB) to also be exempt from the 

Massachusetts emissions inspection to the extent of the waiver or exemption; 

o Changing the requirement for an emissions inspection from within seven days of 

the date of vehicle purchase to within seven days of the date on which the motor 

vehicle is registered in the state to the new owner, as is currently required by the 

RMV; 

o Specifying which waiver provisions apply specifically to transient loaded or twospeed idle tests, and to OBD tests; and

o Clarifying the definition of “tampering” to note that the term includes using a fuel 

that a vehicle is not certified to use or otherwise approved by EPA or CARB.

Proposed revisions to 310 CMR 60.02 can be found in Appendix A. 

III. KEY ISSUES

The federal Clean Air Act as amended in 1990 (CAA) required EPA to establish rules for states 

to follow in designing and implementing vehicle inspection and maintenance programs. Section 

182(c)(3) of the CAA amendments addresses vehicle inspection and maintenance programs. On 

November 5, 1992, EPA issued final rules implementing Section 182 of the CAA amendments of 

19906. The MA program has been designed to comply with EPA requirements except in 

circumstances where the program goes beyond federal requirements (e.g., opacity testing).

 

2 40 CFR Part 51
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Emissions Testing Technology: From Idle to Dynamometer to OBD Test

Beginning in Spring 1983, Massachusetts implemented an I&M program based on a vehicle 

emissions idle test that measured carbon monoxide (CO) and hydrocarbon (HC) emissions at the 

tailpipe while the vehicle was idling. In implementing the 1990 CAA, EPA required that 

MassDEP, as part of its comprehensive plan to improve the state’s air quality, replace its vehicle 

emissions idle test with an enhanced emissions inspection and maintenance program. The 

enhanced program was based on a dynamometer test, which simulated driving conditions while 

measuring CO and HC at the tailpipe, and included NOx testing for the first time in 

Massachusetts. In 1999, MassDEP revised the Massachusetts I&M regulations to reflect the 

enhanced I&M program, and, with RMV, selected a network contractor through a competitive 

bidding process to manage the inspection program.

In April 2001, EPA updated the I&M testing requirements to require testing using vehicles’ own 

OBD systems that started to be built into light duty vehicles beginning with model year 1996. 

MassDEP amended the Massachusetts I&M regulations in 2003 to include EPA’s requirement to 

use OBD systems to test emissions.

EPA’s requirement for the use of OBD systems applied to light-duty vehicles fueled with 

gasoline and other non-diesel fuels (“non-diesel vehicles”) and sold in the U.S. Beginning with 

model year 1996, OBD systems were required to meet specifications known as “OBD II”7. OBD 

II is a standardized protocol in which a vehicle monitors its own emissions control systems with 

an on-board computer and communicates information from the computer to external test 

equipment in an inspection. The OBD protocol monitors the vehicle’s emissions control systems 

under actual driving conditions, rather than the conditions simulated by a dynamometer used to 

test tailpipe emissions. OBD checks provide a more complete assessment of the emission 

control system’s performance: for example, the OBD evaporative control check tests the 

complete vapor control system, not just the gas cap which is checked on vehicles that are not 

equipped with OBD. 

The amendments to the I&M regulations proposed here reflect the changing Massachusetts 

vehicle fleet and improved testing technologies. In 2006, 76% of the vehicles registered in 

Massachusetts were equipped with OBD. By 2009, MassDEP projects that this percent will 

increase to 88%, and by 2012 to 94%. While EPA has required light duty non-diesel vehicles to 

be equipped with OBD since model year 1996, the agency has also required OBD to be installed 

in medium-duty diesel vehicles starting with model year 2007, and medium-duty non-diesel 

vehicles starting with model year 2008. New heavy-duty vehicles are scheduled to begin 

phasing in OBD compliance beginning with model year 2010, and to complete phase-in by

model year 2013. 

To comply with EPA’s requirement to use the OBD approach to the maximum extent possible, 

these revisions of the I&M regulation propose to discontinue dynamometer tailpipe testing and to 

rely on OBD emissions testing, starting with the commencement of the new program contract on 

October 1, 2008. As the Massachusetts vehicle fleet becomes increasingly equipped with OBD, 

 

7

“OBD” in this document refers to OBDII.
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there is a decreasing need for dynamometer tailpipe testing. As the dynamometer equipment that 

was installed in inspection stations in 1999 continues to age, it is increasingly expensive and 

labor intensive to operate, maintain, repair, calibrate, and audit. As the fleet continues to turn 

over, there will be fewer and fewer pre-1996 vehicles in Massachusetts and this equipment 

would be used less and less often. Where the tailpipe test on the dynamometer takes 

approximately fifteen minutes to perform, the OBD emissions test takes only one or two minutes, 

providing shorter wait times for motorists. In addition, the OBD emissions test makes it easier 

for the Agencies to detect and enforce against inspector fraud and vehicles that have been 

tampered with by motorists. 

RMV requires that safety inspections of all vehicles include a check for visible smoke; vehicles 

emitting visible smoke are required to be repaired and re-tested (540 CMR 4.00-4.09). RMV is 

proposing to continue to subject non-OBD compliant light- and medium-duty vehicles (e.g., premodel year 1996 vehicles) to this prohibition, which will help ensure that older vehicles emitting 

enough smoke to be seen by an inspector are repaired. 

The amendments proposed by MassDEP include a new requirement that non-OBD compliant kit 

vehicles (unique or replica vehicles manufactured in lots of less than 500) will also receive a 

separate comprehensive visual test when new and upon change of ownership, to ensure that all 

required emissions control components are installed. Heavy-duty diesel vehicles and mediumduty diesel vehicles more than 10,000 pounds GVWR8

and not otherwise subject to an OBD test 

will continue to receive an opacity test. 

The revisions of the I&M regulation would add a requirement that a computer scan of a new 

vehicle’s OBD system be performed to establish an “electronic fingerprint” of the vehicle’s OBD 

system when the vehicle is new. This scan would not be an emissions test, but would provide 

data that the Agencies could use in the future to determine whether future inspections are being 

conducted properly. It would also provide the vehicle purchaser and the dealer with early notice 

of problems that would need to be resolved before the vehicle receives its first emissions 

inspection. The vehicle owner and dealer/manufacturer would then have a year to address any 

potential problems, if necessary, rather than the 60 day period that is normally be afforded for 

repairs following an emissions test failure. 

The amendments would eliminate the current two-year exemption from emissions testing for 

new vehicles that remain registered to their original owners. Earlier emissions testing would 

identify malfunctions covered by emissions warranties when the warranties are still in effect, 

enhancing consumer protection. 

Malfunction Indicator Light Bulb Check

Current Massachusetts OBD test procedures do not check the operation of the malfunction 

indicator light (MIL) bulb. The amendments would require that the MIL bulb be checked in 

vehicles that fail their OBD test when the MIL is commanded on: 

 

8 All vehicle weights in this document refer to Gross Vehicle Weight Rating or “GVWR”. Vehicle classes are 

defined in Table 1 above.
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 In an initial inspection, the inspector would be prompted to check to see whether the MIL 

bulb is illuminated when the workstation detects that the MIL has been commanded on. 

This bulb check would be performed with the vehicle in a “key on/engine running” 

(KOER) mode. If the bulb is not illuminated, the vehicle would fail its inspection. 

Failure of the MIL to illuminate when commanded on would be listed as a cause of the 

emissions test failure on the Vehicle Information Report (VIR) provided to the motorist. 

 When a vehicle fails this bulb check, its re-inspection would include a “key on/engine 

off” (KOEO) bulb check to verify that the bulb has been repaired. If vehicle repairs were 

unsuccessful and the MIL is still commanded on, the inspector would also be prompted to 

check MIL function in the KOER mode. A waiver would not be issued to a vehicle that 

has this malfunction, and costs for this repair would not count toward waiver cost repair 

limits. 

A KOEO bulb check is proposed only for vehicles that failed the KOER bulb check during their 

initial inspection. When MassDEP developed the current OBD test procedures, consideration 

was given to the probability that vehicles would fail the KOEO bulb check, the likelihood of 

false failures for the KOEO bulb check, and the motorist inconvenience caused by false failures. 

Information from Oregon’s centralized OBD emissions test program (obtained by MassDEP in 

2002) showed a KOEO bulb check failure rate of 0.2%. Even with this low failure rate, Oregon 

opined that this aspect of the test was highly prone to false failures because the MIL stayed 

illuminated in some vehicles for only a very brief period, so that the illuminated bulb was not 

always seen by inspectors. About half of the vehicles failing the KOEO bulb check also failed 

their emissions test because the electronic scan of the OBD system found the MIL was 

commanded on. 

Based on Oregon’s experience, prior to beginning full scale OBD testing in 2004, Massachusetts 

conducted a brief OBD pilot program that included the KOEO bulb check. Of the vehicles that 

failed their OBD test in this pilot program, 4.2% failed the KOEO bulb check. This raised 

concern that inspectors were likely to falsely fail a substantial number of vehicles. The New 

England Service Station and Auto Repair Association commented that the bulb check was 

unnecessary because the MIL command status was being checked by the electronic scan of the 

OBD system, and that some vehicles were likely to have a high false failure rate because their 

MIL does not stay on very long when the key is first turned on, so that the inspector could easily

miss the bulb’s illumination. 

More recent information from other states indicates that KOEO bulb check failure rates remain 

very low. In I&M programs designed with centralized testing, the failure rates range from 0.4-

0.7%, and in decentralized testing, the failure rates range from 0.3-0.6%; however the potential 

for false failures remains high. 

Keyless ignition systems have become more widespread than they were when the Oregon 

program information was developed and the Massachusetts pilot program was conducted. 

Keyless ignition systems operate in a variety of ways: some vehicles automatically start when the 

electronic key approaches the vehicle, while others activate the ignition and require the motorist 
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to merely push a button to start the vehicle. With more of these varied systems achieving market 

penetration, the likelihood that an inspector would miss a bulb that is only illuminated for a short 

time in a vehicle tested in KOEO mode would be expected to increase. 

Another factor makes a KOEO bulb check difficult is the number of self-monitoring warning 

lights populating vehicle dashboards. In addition to the traditional temperature, oil pressure, and 

charging system indicator lights, many dashboards now include indicator lights for antilock 

brake systems, air bag monitors, electronic stability control, active suspension, driving mode 

selection, light monitors (for burned out bulbs), low fuel indicators, loose gas caps, and unclosed 

doors. Add other functions, such as hybrid vehicle power distribution and diesel catalytic 

systems for certain other vehicles, and it is understandable that an inspector might have difficulty

locating the MIL among all the other bulb tests the vehicle performs when the ignition key is 

turned on. 

MassDEP estimates that the average Massachusetts inspector would see about 2-4 vehicles/year 

that fail the KOEO bulb check. Assuming the Oregon finding that half of the KOEO bulb check 

failures also failed because the MIL was commanded on, that leaves 1-2 failures related directly 

to these bulbs per year (assuming the KOEO bulb check failure rate information from other state 

includes no false failures). 

In summary, Massachusetts is not proposing to perform a KOEO bulb check for all vehicles as 

part of the OBD test procedure because: 

 The KOEO bulb check failure rate is low in other states; 

 Vehicles with disabled MILs are likely to be vehicles that fail the electronic scan of the 

OBD system; 

 Vehicles failing the electronic scan of the OBD system because the MIL is commanded 

on will receive a bulb check; 

 The bulb check is becoming increasingly prone to false failures because of changes in 

vehicles themselves; and 

 False failures related to the bulb check raise concerns about costs to motorists in terms of 

both time and money. 

Discretionary Flexibility for Operational Issues

The amendments would provide the Agencies with some flexibility to address unusual or 

unanticipated problems that can affect the operation of I&M program. For example, the 

elimination of the two-year deferral of emissions testing for new vehicles may mean that new or 

substantially redesigned vehicle models may experience design or production problems would 

cause them to fail their initial emissions test if MassDEP does not establish limited alternative 

emissions test procedures or defer the requirement until manufacturers can take corrective action. 

As medium- and heavy-duty vehicle classes are outfitted with OBD systems, vehicle or engine 

manufacturers may experience implementation issues that require states to be flexible. 

In another example, hand controls that allow a handicapped person to operate a vehicle may be 

installed so that they block the OBD port, preventing an OBD inspection from being performed. 
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This type of problem may require that a customized test be developed specifically for an 

individual vehicle, as opposed to a class of vehicles.

MassDEP intends to use the flexibility provisions only to address operational problems, to advise 

EPA in a timely manner when these problems arise, and to make appropriate adjustments in 

response to EPA concerns. 

Opacity Emissions Test Cutpoints for Diesel Vehicles Weighing More Than 10,000 pounds 

EPA established the first emissions standards for smoke, hydrocarbons, oxides of nitrogen and 

carbon monoxide for new diesel engines in 1974. Emissions standards for particulate matter 

were added for new diesel engines beginning in 1988. Over time, deterioration and poor 

maintenance of diesel engines can cause excessive levels of pollution that is seen as black 

smoke. Inspections that use opacity tests to measure the density of black smoke identify vehicles 

that need to be repaired. Although the smoke opacity test does not test the diesel vehicles at their 

respective engine emissions standards (as with the OBD test), it can identify vehicles that exceed 

certain opacity levels (or “cutpoints”): the percent opacity (proportion of black smoke in the 

vehicle’s exhaust) is used as an indicator of the level of particulate matter that the vehicle is 

emitting. 

Smoke inspections on older trucks and buses have spurred their owners to conduct preventative 

maintenance. The opacity inspection protocol used in most northeast states (including 

Massachusetts) is the SAE J1667 Snap-Acceleration Smoke Test Procedure for Heavy-Duty

Diesel Powered Vehicles9. In 1999, EPA issued “Guidance to States on Smoke Opacity 

Cutpoints to be used with the SAE J1667 In-Use Smoke Test Procedure”10 supporting the 

cutpoints that the program currently uses to identify vehicles needing repairs. Also in 1999, 

Massachusetts joined eight other northeastern states in signing a Memorandum of Understanding 

to develop smoke opacity inspection programs that are as consistent as possible. Massachusetts 

began conducting opacity inspections in 2000 on diesel vehicles model year 1984 and newer. 

Under the proposed amendments, diesel vehicles more than 10,000 pounds GVWR that are not 

OBD-equipped would continue to receive the opacity test in Massachusetts.

Recent developments in the diesel engine industry and improvements in the emissions control 

technologies for diesel engines combine to make diesel exhaust much cleaner than it has been in 

the past. EPA’s requirement that all on-road diesel vehicles use ultra low sulfur diesel fuel11

(that took effect on October 15, 2006), has allowed for more stringent engine emission standards 

beginning with model year 2007. As a result, new diesel vehicles are being equipped with diesel 

particulate filters to lower emissions.

As a result of these developments, New Jersey is now considering lowering its diesel opacity

cutpoints for heavy duty trucks and buses, which would be used in both roadside inspections and 

 

9

The Snap-Acceleration Smoke Test Procedure for Heavy-Duty Diesel Powered Vehicles, 1996-02, issued by the 

Society of Automotive Engineers (SAE).

10 Guidance to States on Smoke Opacity Cutpoints to be used with the SAE J1667 In-Use Smoke Test Procedure, 

February 25, 1999. http://www.epa.gov/oms/regs/hd-hwy/smokguid.pdf

11 Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway 

Diesel Fuel Sulfur Control Requirements, 40 CFR 69, 80 and 86, Federal Register January 18, 2001
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their IM program, based on their study of 70,000 New Jersey smoke opacity inspections12. 

MassDEP is proposing in this regulation package to adopt these lower diesel opacity cutpoints, 

which are also being considered for adoption by other northeast states. 

Emissions Waivers

EPA allows states to offer waivers from compliance with emission standards, in order to balance 

repair costs for failing vehicles with the environmental benefits that result from successful 

repairs and provide some economic relief to owners of failed vehicles. In Massachusetts, 

waivers have been made available to motorists whose vehicles have failed their re-inspections 

after having met certain repair criteria, which include a requirement that emissions-related 

repairs are performed by a registered repair technician. Emissions waivers are valid until the 

vehicle’s next emissions inspection. 

In 2005 and 2006, approximately 2.9 million initial OBD emissions tests were administered and 

approximately 9.2% (272,000) vehicles failed. The Agencies issued 210 waivers to OBD 

vehicles that failed their initial inspection in 2005 and 2006 (less than 0.1% of vehicles failing an 

initial OBD test). MassDEP attributes the low emissions waiver rate to: 

 Motorists wanting their vehicle repaired properly;

 The program requiring emissions repairs be performed by registered repairers to qualify

for waivers; 

 The program providing assistance to motorists seeking emissions repairs and repairers 

performing the work; and 

 The program prohibiting waivers for vehicles with misfire and catalytic converter 

problems.

Both the number of vehicles tested and the number of emissions failures are expected to increase 

as annual testing replaces biennial testing. However, both are expected to increase at the same 

rate, so that the failure rate is expected to remain roughly constant. With the changes proposed 

in this package to the criteria for obtaining a waiver, MassDEP does not anticipate a significant 

change in the rate at which waivers are issued: it is expected to remain at or below 1% of 

vehicles failing the OBD emissions test. As required by EPA, the emissions benefit of the 

proposed I&M program has been modeled with this emissions waiver rate. 

The current waiver repair criteria and expenditure requirements took effect with the start of the 

current I&M program in 1999. The expenditure requirements use three tiers, to allow older 

vehicles to meet waiver eligibility requirements at lower costs than newer vehicles (see Table 3 

below). While the current expenditure limits were lower than those required by EPA ($450 in 

1989 dollars, adjusted based on changes in the Consumer Price Index or “CPI”), they were 

approved by EPA because MassDEP also prohibited issuing waivers to vehicles with after-repair 

emissions that are more than three times the pass/fail cutpoint and to OBD vehicles with engine 

misfire or catalytic converter problems identified by the OBD system. These additional criteria 

made the Massachusetts waiver requirement at least as restrictive as the higher waiver 

expenditure limit required by EPA. 

 

12 Northeast States Heavy-Duty Diesel Engine Repair Study, NESCAUM Heavy-Duty Diesel Workgroup, Repair 

Study Sub-Group, December 2006 – DRAFT
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The amendments propose to increase the waiver expenditure threshold initially to the updated 

level established by EPA for vehicles five years old and newer, and would decrease the threshold 

by $100 or $200 for older vehicles. By retaining the three tiers, the program would continue to 

require lower expenditures for older vehicles. Table 3 compares the proposed initial repair 

expenditure requirements with the levels used in the current program. The $750 in Table 3 

reflects the EPA-mandated $450 adjusted for CPI through 2007.

Table 3

Waiver Expenditure Requirements

Vehicle Age Current Waiver 

Expenditure 

Requirement

Proposed Initial 

Waiver 

Expenditure 

Requirement

Five model years old or newer $400 $750

More than five but less than 10 

model years old 

$300 $650

More than 10 model years old. $200 $550

In addition to increasing the base expenditure thresholds, the amendments also propose to adjust 

the thresholds annually, by the percentage (if any) that the CPI for the preceding calendar year 

differs from the CPI for 1989 (the year on which EPA based the original thresholds). Adjusted 

expenditure limits would be rounded to the nearest five dollars. The limits for vehicles between 

five and ten years old, and for vehicles more than ten years old, would be adjusted by subtracting 

$100 and $200 respectively from the adjusted limit for vehicles five years old and newer. 

MassDEP would publish adjusted expenditure limits on the program’s web site for the Enhanced 

Emissions and Safety Test Program, as well as informing motorists through inspection stations 

and registered repair shops. The first adjustments would take effect on January 1, 2010. 

Although the repair expenditure requirements for older cars will still be $100-$200 less than 

EPA requirements, MassDEP is proposing to retain the program’s current practice of not issuing 

waivers for vehicles with engine misfire or catalytic converter problems. In addition, waivers 

would also not be available for hybrid vehicles with problems with their energy storage devices, 

or for problems involving particulate filters on diesel vehicles. Under the amendments, waivers 

would only be available for vehicles registered for personal use (i.e., not for commercial 

vehicles), which would ensure that waivers would not be issued for more than 1% of the vehicles 

that fail an initial inspections, as required in the I&M SIP. 

MassDEP is seeking comment on the proposed repair expenditure amounts for the emissions 

waiver and the revised criteria for waivers for OBD vehicles.

Economic Hardship Failure Repair Extensions

In some situations, a single major vehicle component must be repaired or replaced to enable a 

vehicle that has failed its initial inspection to resolve diagnostic trouble codes and pass its re-test; 
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these can include rebuilds or replacements of transmissions and engines. These repairs usually 

require significant expenditures, and can create an economic hardship for some vehicle owners. 

Therefore, the amendments propose to establish a one-time extension of the deadline for fixing 

emissions problems in certain situations. To qualify for this extension, the repair or replacement 

cost would need to be estimated by a registered repair technician to be more than 1.5 times the 

applicable waiver repair expenditure limit for a vehicle of that age. To obtain the extension, the 

motorist would need to bring the vehicle to a location designated by the MassDEP or RMV for 

an assessment, and the Agency (or its designee) would need to agree with the findings of the 

registered repairer. 

The extension would not be available for commercial vehicles, vehicles that show evidence of 

emissions control system tampering, or vehicles that fail the safety inspection. Also, it would not 

be available for inspection failures associated with initial registrations or transfers of ownership. 

The extension would not be renewable. It would be valid until the vehicle’s next emissions 

inspection: at that time, the vehicle would be required to pass the emissions test. This provision 

is intended is to give motorists extra time to pay for expensive major repairs, such as rebuilding 

or replacing a transmission or engine. 

MassDEP is seeking comment on the proposed economic hardship failure proposal in general, 

and specifically on the proposed threshold value of greater than 1.5 times waiver expenditure 

limit for the vehicle’s age. 

Registered Repair Technicians

Air quality improvements from inspection and maintenance programs ultimately are obtained 

from effective repairs. In addition, vehicle owners expect that repairs required to reduce 

emissions will be accurate and cost effective. Because an increasing number of model year 1996 

and newer vehicles are expected to fail when the program implements annual emissions testing, 

the Agencies place considerable emphasis on promoting proper emissions repairs through a 

registered repairer network. 

Registered repairers have been, and will continue to be, an important component of the I&M 

program. Their knowledge and training in the repair of emissions systems is expected to allow

the program to meet the commitment that MassDEP is making to EPA in its I&M SIP, i.e., to 

maintain the proportion of waivers issued at or below 1% of failing vehicles. Since an increasing 

portion of the Massachusetts vehicle fleet is OBD compliant, and OBD compliant light- and 

medium-duty diesel vehicles will be required to pass an emissions test, the registered repairer 

program needs to be updated to better serve motorists. 

To become a registered repair technician under the current program, applicants must complete 

required MassDEP-approved training and be either ASE L-1 certified for non-diesel vehicles or 

ASE L-2 certified for diesel vehicles. However, the L-2 certification applies only to heavy-duty 

diesel engines. Therefore, the proposed amendments would expand the registered repairer 

network to include technicians who specialize in light- and medium-duty diesel vehicles. The 

proposed amendments would also take advantage of equivalent engine- and manufacturerspecific certifications by allowing registered repairers to be certified specifically for repairing 
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only those types of engines or vehicles at the repair facility or dealership recognized by the 

engine or vehicle manufacturer at which the registered repairer is employed. 

The amendments propose to allow MassDEP to remove repairers from the list of registered 

repair technicians if the repairer does not maintain the requirements for qualification, if he/she 

provides false documentation of the repair or the costs of the repair to the Agencies, or MassDEP 

determines that he/she has been a party to deceptive or fraudulent business practices related to 

emissions repairs or to environmental protection. In addition, MassDEP would expand its ability

to remove repair shops from the list of registered repair facilities to include situations where the 

shop provides false documentation of repairs or their costs to the Agencies, and where the repair 

shop has been determined to have been a party to deceptive or fraudulent business practices 

related to emissions repairs or environmental protection. The list of registered repair facilities 

would continue to be maintained by MassDEP on the Enhanced Emissions and Safety Test 

Program’s web site.

IV. AIR QUALITY IMPACTS 

In order for the proposed I&M regulation to be approved by EPA as a revision to the 

Massachusetts ozone SIP, MassDEP must demonstrate how the program changes will reduce 

emissions from on-road mobile sources using EPA’s approved model (MOBILE6). This model 

uses specific Massachusetts’ data (such as fleet age by vehicle class, vehicle miles traveled, and 

ambient temperatures) in combination with national factors established by EPA (such as 

emission factors for vehicles by age and class). The model also uses parameters that describe the 

emissions benefits of all of the Commonwealth’s mobile source emission control programs (such 

as Stage II Vapor Recovery and Reformulated Gasoline). The model calculates on-road 

emissions from the Massachusetts vehicle fleet (in grams per mile) that are expected to remain 

after all of the mobile source emission control programs are taken into account. When these 

emission estimates are combined with estimates of vehicle miles traveled by the fleet, the overall 

inventory of on-road vehicle emissions can be expressed in terms of tons per summer day (tpsd).

Section 110(n) of the U.S. Clean Air Act13 (the “savings clause”) states that if a program 

required by the Act is revised, it must maintain at least the emission benefits demonstrated when 

it was first approved into the SIP. Since EPA requires Massachusetts to implement an I&M 

program due to the Commonwealth’s non-attainment status with respect to ground level ozone, 

the revised program that these regulation amendments would establish must maintain at least the 

level of emission reductions that were demonstrated for the current I&M program.

MassDEP has modeled the emissions impact of the proposed program, which relies on annual 

OBD testing and removes requirements for transient testing for pre-model year 1996 vehicles, 

using EPA’s MOBILE6 model. MassDEP assumed the proposed program would begin in 

October 2008 and would exempt vehicles that are 15 or more model years old from the emissions 

testing requirement. The emissions benefits of the proposed program were compared with those 

estimated for the current program with biennial emissions testing (transient testing for model 

year 1984-1995 vehicles and OBD testing for model year 1996 and later vehicles). The 

 

13 The Clean Air Act, (42 U.S.C. 7401097626). http://www.epa.gov/ttn/oarpg/gen/caa-pdf.pdf
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estimated figures for vehicle miles traveled per day by the Massachusetts fleet as a whole that 

were used to determine the emissions figures are shown in Table 4.

Table 4

Estimated Vehicle Miles Traveled Used to Model Air Quality Impacts of Proposed Changes 

in the Massachusetts I&M Program

2009 2010 2011 2012 2018

Estimated VMT per day 149,228,000 149,962,000 150,694,000 151,427,000 155,700,000

Table 5 and the graph below show the results of the modeling for 2009 through 2012, and for 

2018 (the final analysis year required by EPA for the 8-hour Ozone SIP). The emission figures 

show the tons per summer day of on-road mobile source emissions that would remain if the 

current biennial testing program were to be continued into the future, under the proposed annual 

OBD testing program, and the difference, or delta, between the two.

Table 5

Comparison of Emissions for Current and Proposed I&M Programs

Pollutant

2009

(tpsd)

2010

(tpsd)

2011

(tpsd)

2012

(tpsd)

2018

(tpsd)

Current IM 

Program

VOC 73.61 67.18 61.60 56.32 38.97

NOx 224.7 196.5 170.6 147.7 65.0

CO 1002.1 938.6 885.2 837.8 711.5

Proposed IM 

Program

VOC 73.78 66.87 61.04 55.86 38.78

NOx 224.0 195.4 169.2 146.4 64.2

CO 1003.7 932.0 872.5 824.9 701.3

Delta = 

Current - Proposed 

IM Programs

VOC -0.17 0.31 0.57 0.46 0.19

NOx 0.6 1.1 1.5 1.3 0.7

CO -1.6 6.6 12.7 12.9 10.2
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Emissions Delta Between

Current and Proposed I&M Programs

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

20092010201120122018

Delta (tons per summer day)

VOC

NOx

CO/10

These figures show that an annual OBD program, without transient testing, will result in slightly

more VOC emissions (0.17 tpsd) in 2009 than would be expected if the current program were to 

be continued. However, an expected decrease in NOx emissions (0.6 tpsd) leads to a net 

reduction in ozone forming pollutants. While the modeling also shows a slight increase in CO 

emissions (1.6 tpsd) in 2009, the pollutants that are most important for ozone production are 

NOx and VOCs.

For the following reasons, MassDEP believes the program envisioned for the new contract meets 

the requirements of the U.S. Clean Air Act’s savings clause: 

 These results assume no carryover of emission reduction benefits from the current 

transient testing program that will end on September 30, 2008. A carryover effect would 

recognize that emissions from most of the vehicles that currently receive a biennial 

transient test will not automatically rise to levels that would result in a failing test 

immediately at the end of the current program, and would allow these benefits to be 

estimated in the modeling as a benefit in the proposed I&M program. Because the 

MOBILE6 model does not recognize any carryover effect, it assumes the tailpipe testing 

benefit ends as soon as the program stops. MassDEP believes this is unrealistic. EPA 

Region 1 has agreed that residual credit from the tailpipe testing would make up for the 

small increase in HC and CO emissions that the model predicts in 2009.

 The MOBILE6 model calculates emissions on the basis of complete calendar years, and 

does not allow for testing to begin in October of a calendar year, when annual testing 

under the proposed program will begin. Therefore, the model does not account for 

emission benefits that would be earned between October 1, 2008 and December 31, 2008.
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 Table 6 below shows that the estimated difference in emissions benefits between the 

current program and the proposed program are well within the model’s margin of error. 

In consideration of all of these factors, MassDEP believes the proposed program will achieve 

the reductions needed for the SIP. Specifically, in 2009, the 0.17 tpsd difference for VOCs 

represents less than 0.3% of VOC emissions modeled; and the 0.6 tpsd difference for NOx 

represents an improvement of almost 0.3% of NOx emissions modeled. For CO, the 1.6 tpsd 

difference represents less than 0.2% of CO emissions modeled. Table 6 shows that the 

proposed program will create very close to 100% of the air quality benefits of the current 

program for VOC and CO in 2009, and more than 100% for NOx. 

Table 6

Detailed Comparison of Emissions for 2009

Emissions from Programs Benefit from Programs Differences between Programs

2009

No IM 

Program

(tpsd)

Current 

Program

(tpsd)

Proposed 

Program

(tpsd)

Benefit of 

Current 

Program

(tpsd)

Benefit of 

Proposed

Program

(tpsd)

Delta

Between

Benefits

(tpsd)

Delta

vs.

Current 

Program

Proposed

vs.

Current 

Program

VOC 84.57 73.61 73.78 10.96 10.79 -0.17 0.23% 98.4%

NOx 241.1 224.7 224.0 16.4 17.0 0.6 0.27% 103.7%

CO 1224.9 1002.1 1003.7 222.9 221.3 -1.6 0.16% 99.3%

Table 7 shows that the proposed program’s slight increase in VOC emissions modeled for 

2009 over those expected from continuing the current programs will disappear beginning in 

2010, when the emissions benefits of the proposed annual OBD program are projected to go 

beyond those of the current program with biennial transient testing.

Table 7

Detailed Comparison of Emissions for 2010

Emissions from Programs Benefit from Programs Differences between Programs

2010

No IM 

Program

(tpsd)

Current 

Program

(tpsd)

Proposed 

Program

(tpsd)

Benefit 

Current 

Program

(tpsd)

Benefit 

Proposed

Program

(tpsd)

Delta

Between

Benefits

(tpsd)

Delta

vs.

Current 

Program

Proposed 

vs. 

Current 

Program

VOC 77.98 67.18 66.87 10.81 11.11 0.31 0.46% 102.8%

NOx 213.0 196.5 195.4 16.5 17.7 1.1 0.56% 106.9%

CO 1160.0 938.6 932.0 221.4 228.0 6.6 0.70% 103.0%

In addition, Table 5 and its associated graph show that the emissions of NOx and VOC under 

the proposed I&M program will continue to remain below the emissions of the current I&M 

program through 2018, helping Massachusetts to attain the ozone standard over time. While 

the difference between the two programs decreases somewhat after 2011, please note that 
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MOBILE6 does not allow for any credit from the OBD emissions testing of light-, medium-, 

and heavy-duty diesel vehicles that would begin on the schedule described in Table 1 above.

V. ECONOMIC IMPACTS

There are three main changes in the proposed regulation that are expected to have an economic 

impact on the Commonwealth: (1) the elimination of dynamometer tailpipe emissions tests; (2) 

the requirement for more stringent opacity cutpoints for diesel vehicles more than 10,000 pounds 

GVWR; and (3) the increase in emissions test frequency from biennial to annual testing.

Elimination of Dynamometer Tailpipe Testing

With the existing dynamometer workstation equipment reaching the end of its useful life, this 

proposed regulation allows for a much less expensive replacement with new OBD-only

workstation equipment. New OBD-only workstations will not need emission gas analyzers, 

oxygen sensors and air filters. While the new stations will still need “consumable” items such as 

stickers, printer ink and paper, they will not require other (more expensive) consumable items 

such as gases needed to calibrate the emissions gas analyzers. In general, the new OBD-only 

workstation equipment will be simpler, with fewer moving parts. Therefore, it will also cost 

much less to maintain workstations and to replace them when needed. The total cost for a new 

OBD-only workstation, including installation and maintenance, is expected to be approximately 

$5,000 vs. approximately $80,000 for the old dynamometer workstation. 

In addition, it will be much less labor intensive for the Agencies to audit the performance of the 

new OBD-only workstation equipment (to ensure that they are providing emission tests within 

acceptable ranges of tolerance). This will allow the Agencies to perform the QA/QC audits 

themselves, rather than hiring an outside technical support contractor to perform the audits 

(which could save the Commonwealth approximately $600,000 per year).

More Stringent Opacity Test Cutpoints

The NESCAUM Heavy-Duty Diesel Workgroup14 analyzed the proposed lower cutpoints by

reviewing heavy-duty diesel truck smoke inspection data from various states to compare current 

average smoke levels to the current and proposed cutpoints. These data suggest that most of the 

diesel engines in this study would meet the proposed cutpoints, but that tighter cutpoints would 

reduce excessive black smoke from enough additional vehicles to provide a benefit for 

Massachusetts’ air quality. 

A review of opacity tests performed in 2004 and 2005 on Massachusetts’ diesel vehicles greater 

than 10,000 pounds GVWR was done by I&M program staff in conjunction with the NESCAUM 

study. This review showed that 1.6% of diesel vehicles in Massachusetts fail the opacity test at 

the current cutpoints, and indicated that an additional 3% of diesel vehicles (approximately 2000 

additional vehicles) in Massachusetts could be affected by the proposed cutpoints in the first 

 

14 Northeast States Heavy-Duty Diesel Engine Repair Study, NESCAUM Heavy-Duty Diesel Workgroup, Repair 

Study Sub-Group, December 2006 – DRAFT
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year. These vehicles would need to receive some level of repair to pass the smoke opacity

inspection. Not all of these vehicles would necessarily fail, however, because many fleets repair 

and test their own vehicles and would be likely to perform needed repairs before the vehicles 

were tested. Most of these affected vehicles (~60%) are expected to be older (model years 1984 

to 1990) trucks.

Available smoke opacity repair data were also analyzed by the NESCAUM Heavy-Duty Diesel 

Workgroup15. These data suggest that most of the repairs required to bring trucks that fail based 

on the current cutpoints back into compliance cost less than $1,000 on average, with average 

repair costs for older trucks (1984 - 1990) less than $500. Older trucks are expected to be the 

most affected by the adoption of the proposed cutpoints, and they are often the least expensive to 

repair. Diesel vehicles greater than 10,000 pounds GVWR would continue to be ineligible for an 

emissions waiver under the proposed I&M regulation, since waivers would not be provided to 

commercial vehicles (virtually all of the vehicles in this class are commercial vehicles).

The proposed cutpoints have not been implemented in any state yet (although they are expected 

to be proposed by the New Jersey Department of Environmental Protection before the end of 

2007), so there are no data available to evaluate actual increases in repair costs that would be 

associated with them. However, since most of the trucks repaired under the current cutpoints 

would easily pass the opacity test under the proposed cutpoints (with no additional repairs 

required), this impact is expected to be minimal. 

Mass DEP seeks comment on the proposed cutpoints, estimated cost of repairs and worthiness of 

making this change in the diesel testing program. 

Increase in Emissions Test Frequency

Changing from biennial to annual emissions testing is anticipated to result in an increase in the 

annual number of vehicles that fail their emissions test, with a corresponding increase in motorist 

expenditures for repair costs. 

Vehicles that fail the OBD test will be required to be repaired whenever they fail, which may be 

annually, instead of biennially. This will put upward pressure on total repair costs. However, for 

some motorists, by requiring repairs earlier than would have been required with biennial testing, 

the overall cost of repairs may be reduced because defects can be repaired before significant 

deterioration or damage to other components could occur. Additionally, OBD systems are 

designed to provide qualified repair technicians with diagnostic information allowing them to 

pinpoint likely causes, allowing more accurate diagnosis and less costly repairs than hit-or-miss 

component replacement. 

Motorists who cannot repair their vehicles and pass a re-test have been able to qualify for a 

repair cost waiver when repairs exceed $200-$400, depending on the age of the vehicle. In 2006, 

only 165 waivers were granted, less than 0.01% of the emissions test administered that year. 

Under the proposed regulations, motorists would be required to spend $550-$750 to qualify for a 

 

15 Northeast States Heavy-Duty Diesel Engine Repair Study, NESCAUM Heavy-Duty Diesel Workgroup, Repair 

Study Sub-Group, December 2006 – DRAFT
MA SIP Revision: Table of Contents Item 6 – Background and Technical Support for Public Hearings

MA SIP Revision, 310 CMR 60.02, the Massachusetts Motor Vehicle Emissions Inspection and Maintenance Program. 

Documentation of IM SIP Revision consistent with 42 USC Section 7511a and Section 182 (c)(3)(A) of the Clean Air Act 25

waiver. In EPA’s 2005 analysis of OBD vehicles16, the average repair cost was found to be 

$453, with a median repair cost of $258 – expenditures that are well below the proposed 

expenditure requirement for a waiver. Therefore, the move to annual testing is not expected to 

result in a substantial overall increase in motorists’ costs. 

Even though repair costs are not estimated to be high in general, some vehicles may require 

high-cost repairs to fix transmission failures or serious engine damage. Under the proposed 

regulation, owners of these vehicles would be able to use a one-year extension to schedule the 

needed repairs as their finances allow, or to replace the vehicle if they feel it is not worthwhile to

repair it. 

Diesel vehicles greater than 10,000 pounds GVWR would have an annual smoke opacity test 

under the proposed regulation, rather than the biennial test that is currently administered, unless 

they have OBD systems that would allow OBD testing, which is not currently required. The start 

of emissions testing of these vehicles will likely require a small number of owners of vehicles 

that are not currently getting emissions tests to repair them in order to pass. Diesel vehicles are a 

small fraction of vehicles subject to the emissions test, and the number of diesel vehicles 

expected to fail the OBD test is low. Also, until the model year 2007, emissions control systems 

for diesel vehicles consisted mostly of minor engine adjustments and the use of exhaust gas 

recirculation to meet engine EPA’s emissions standards, so the cost of repairs for failing vehicles 

is expected to be reasonable. As a result, OBD testing of diesel vehicles is not expected to have 

a substantial impact on overall motorist repair costs. 

The proposed regulation would exempt light- and medium-duty vehicles from emissions testing 

when they are 15 years old. In 2006, the percentage of the fleet over 15 years old was less than 

10%, representing a small segment of total light- and medium duty vehicles. Because older 

vehicles are driven fewer miles, they also represent a small fraction of total miles traveled. 

Exempting these older vehicles is expected to put a downward pressure on total repair costs. 

For newer OBD vehicles, eliminating the new vehicle exemption will provide an added degree of 

consumer protection for motorists by enabling them to get a new car fixed while it still under 

warranty.

 

16 “High-mileage Study of On-Board Diagnostic Emissions,” by EPA, published in Air and Waste Management in 

2005