State of California 

AIR RESOURCES BOARD 

Addendum to the Supplement to the Final Statement of Reasons for Rulemaking 

Including Summary of Comments and Agency Responses 

PUBLIC HEARING TO CONSIDER AMENDMENTS TO THE REGULATIONS 

APPLICABLE TO PORTABLE DIESEL ENGINES AND DIESEL ENGINES USED IN 

OFF-ROAD AND ON-ROAD VEHICLES 

Public Hearing Date: January 28, 2010 

Agenda Item No.: 10-1-2 

On December 9, 2010, ARB staff submitted part 2 of the rulemaking package for the 

amendments to the regulations applicable to portable diesel engines and diesel engines 

used in off-road and on-road vehicles to the Office of Administrative Law for review and 

approval. The ARB is submitting this addendum to the supplement to the Final 

Statement of Reasons for insertion in Office of Administrative Law (OAL) File Number 

2010-1209-01S. 

Nonsubstantial Changes Made to the Final Regulation Order

ARB has made some minor nonsubstantial changes to the final regulation order for 

punctuation, grammar, accuracy, clarity, and proper authority and reference citations. 

The changes made do not materially alter any requirement, right responsibility, 

condition, prescription, or other regulatory element of any California Code of 

Regulations (CCR) provisions. They are as follows:

1. 13, CCR, 2452(mm)(1) ~ Removed the strike-out of the comma after 2006. 

2. 13 ,CCR, 2453(f) ~ Added an “s” to the word “district” in the second to last sentence 

to make it plural. 

3. 13, CCR, 2456(f)(1) ~ Corrected the word “compress-ignition” in the last sentence to 

“compression-ignition” by adding in underline the “ion”. 

4. 13, CCR, 2458(a)(1)(D)&(E) ~ Added semi-colons after both of these sections for 

consistency. 

5. 13, CCR, 2458(a)(2)(A) ~ Corrected the capitalization error by making “Engine” 

“eEngine”. 

6. 13, CCR, 2458(b) ~ Corrected the word “regulation” just prior to January 1, 2007 by 

adding an “s” to make it plural like it is in the current code. 

7. 13, CCR, 2458(g) to (h) ~ The “*****“ was removed as it is unnecessary. 
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8. 13, CCR, 2451(c)(4) ~ added the date (2009) to the referenced 40 CFR 60.671 

9. 17, CCR, 93116.1 – 93116.3 ~ Changed all the “California Code of Regulations” 

references to “Cal. Code Regs.” in order to be consistent with what was done in the title 

13 sections. 

10. 17, CCR, 93116.2(a)(20) ~ Corrected the “an reduction” in this subsection to “a 

reduction” by striking through the n. 

11. 17, CCR, 93116.3(b)(2)(E)2. ~ At the very end of the subsection, corrected “(E)(2)” 

to “(E)2.” 

12. 17, CCR, 93116.3(c)(1). In the chart, on the fourth column the code has the 

greater-than-or-equal-to sign, which should be the greater than sign. This was 

corrected by striking the greater-than-or-equal-to sign “≥” and underlining the greaterthan sign “>”. 

Summary and Response

Comment: Comment letters 1 and 11 raise the issue of questionable health 

justification for these regulations because of reports of an ARB diesel particulate matter 

health effects researcher having admitted to falsifying his credentials. 

Agency Response: While the commentor is correct in that Mr. Tran falsely claimed to 

have a Ph.D. degree from UC Davis, we still stand behind the conclusions of the PM2.5 

Mortality staff report because it went through a rigorous, independent scientific peer 

review prior to the report’s release, and the report was re-reviewed in light of the 

concerns about Mr. Tran’s role. All of the reviews found that the report conclusions 

were well founded and properly supported. ARB staff continues to fully support the use 

of the report’s findings in our programs to reduce diesel particulate matter. Further 

information on how we addressed these issues and reached this conclusion is 

presented below. 

Overall Efforts to Determine the Scientific Credibility of the PM2.5 Mortality Study: The 

PM 2.5 Mortality staff report went through three levels of formal, independent, external 

peer review before the report was finalized, and did not rely upon the research or 

original work of ARB staff. However, in light of the external concerns about Mr. Tran’s 

credentials and honesty, iwe asked all ten external reviewers (identified below) to rereview the report. All of the reviewers confirmed their original comments on the report. 

For the reasons summarized below, we continue to be confident of the validity of the 

conclusions of the PM2.5 Mortality report. 

First, we only used scientific publications from the open peer-reviewed literature. We 

considered 78 peer-reviewed scientific journal articles (including Professor Enstrom’s 

publication) and eight reports from the National Academies of Science, the U.S. 
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Environmental Protection Agency and the World Health Organization. We did not 

include secondary literature, such as books or opinion pieces. 

Second, we received comments throughout the process (including review of the final 

report) from our three advisors: Dr. Jonathon Levy from Harvard, Dr. Arden Pope from 

Brigham Young University and Dr. Bart Ostro from the Office of Environmental Health 

Hazard Assessment. They publish frequently in the areas of air pollution and statistical 

relationships with premature death, the main subject of our report, and concurred with 

our findings. 

Third, our draft report was reviewed following the Cal/EPA external scientific peer 

review guidelines for independent review. In this process the UC Berkeley Institute of 

the Environment selects the peer reviewers without input from staff. Staff was only 

allowed to submit a list of individual who may have a conflict of interest. Furthermore, 

candidates were accepted as reviewers only if the disclosure information showed they 

had no conflict of interest related to the report. The six reviewers identified by 

UC Berkeley and selected by the Cal/EPA Project Director to review the proposed 

methodology in the PM2.5 Mortality staff report were: Dr. Jeff Brook from Environment 

Canada, Professor Mark Eisner of UC San Francisco, Professor Richard Flagan of the 

California Institute of Technology, Professor Alan Hubbard of UC Berkeley, Professor 

Joel Kaufman of the University of Washington, and Professor Joel Schwartz of Harvard 

University. Collectively, their expertise is based on research in the areas of chronic 

obstructive pulmonary disease related to air pollution, statistical analysis of 

epidemiological data, particle formation and measurements in air, air quality risk 

management, air pollution and daily mortality associations, and epidemiology. They all 

concurred with our basic conclusions. 

In addition, the report went through several levels of informal internal review. 

Linda Tombras Smith, a Ph.D. in Chemistry (with a Biochemistry thesis topic) from 

UC San Diego with lead experience on PM and other major ambient air quality standard 

reviews, oversaw the entire project and reviewed all versions of the report. Dr. Smith 

was Mr. Tran’s direct supervisor. 

At the request of the Engine Manufacturers Association, the diesel PM exposure 

estimates were reviewed by Professor Philip Hopke of Clarkson University. Dr. Hopke 

was supportive of the basic conceptual framework of ARB’s approach. 

At the request of Board Chairman Mary Nichols, ARB staff convened a panel of 

worldwide PM health effects experts to discuss two important aspects of the staff report, 

the threshold of PM2.5 health effects and the linearity of the dose-response relationship. 

Participants included U.S. EPA, Environment Canada, the World Health Organization, 

the Chairs of U.S. EPA’s Clean Air Scientific Advisory Committee and Cal/EPA’s 

Scientific Review Panel, the Health Effects Institute, and several internationally 

recognized academic researchers. There was general concurrence on the issues 

discussed. 

Comment: Comment letter 5 says the inventory is wrong and not adjusted for the 

economic decline. 
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Agency Response: ARB disagrees. The accuracy of the inventory of certain on-road 

sources was questioned several years ago. However, the emissions sources subject to 

the Portable ATCM and eligible for the Portable Program are non-road sources and 

were not included in that inventory. Hence any discrepancies that may have existed 

would not impact the non-road inventory. ARB acknowledges that the California 

economy has been impacted by the world wide recession. Further, because of the 

uncertainty of the long term effects of the recession, quantifying this impact for inventory 

purposes would be at best problematic. 

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Comment: Comment letter 22 says the one-year extension clock should begin to run 

once ABR has received a waiver from US EPA to regulate these engines. 

Agency Response: ARB disagrees. The one year extension provision was designed 

to provide owner/operators with an option to address the ban on Tier 0 engines. This 

option is not an emissions standard and would therefore be enforceable without need of 

USEPA authorization. 

Further Discussion

OAL requested information on the context and reasons for the deletion which occurred 

in the section 15-day notice in section 2451(c)(9)? 

The language in question was included in the regulation during the energy crisis, back 

in 2000, 2001 to address a specific issue that arose as a result of the times. People 

would sign up in demand reduction programs to reduce their energy costs, but when the 

utility would call on them to reduce their load they would go out and rent a portable 

power unit to power their stationary source. (This issue was discussed in the ISOR at 

the time.) I think everyone is in agreement that the energy crisis is now over, so we see 

the provision as obsolete and did not see any reason to keep the provision in. 

Section 2451(c) provides examples of when portable power cannot be used. For 

several reasons, the issue of what constitutes a remote location has become a 

discussion topic. Rather than going in and developing new definitions, and other 

regulatory language, trying to accommodate new situations, we believe it is better to 

remove the provision because the reason for it no longer exists. 

The commenters were concerned that they could no longer use portable power in 

remote locations. This was a misunderstanding on their part. It is simply that they 

cannot use portable power to operate stationary sources where grid power is available. 

This has always been the case. We discussed this matter with the commenters and 

believe that they now understand the change and don't have a problem with it.