BOARD MEETING DATE: October 6, 2006
AGENDA NO. 15

  REPORT:

Notification of State-Approved Cancer Risk Value for Diesel Particulate Matter from Internal Combustion Engines and Public Consultation Meeting to Discuss Regulatory Options

SYNOPSIS:

Cancer and chronic health risk values were approved for Diesel Particulate Matter (diesel PM) from internal combustion engines by the Office of Environmental Health Hazard Assessment (OEHHA) and adopted by CARB in 1998.  To allow the state to develop statewide permitting guidelines and AB 2588 guidelines, diesel PM was not immediately added to the list of toxic air compounds in Rule 1401 – New Source Review of Toxic Air Contaminants.  The AQMD staff is evaluating a variety of regulatory options for addressing diesel PM from internal combustion engines for new and existing sources.  A Public Consultation meeting is scheduled to solicit public comments regarding regulatory options to address diesel PM in new and existing sources in the AQMD.

COMMITTEE:

Not Applicable

RECOMMENDED ACTION:

Receive and file.

Barry R. Wallerstein, D.Env.
Executive Officer

Background

Rule 1401 – New Source Review of Toxic Air Contaminants establishes permitting requirements for new, relocated and modified sources that emit one or more of the toxic air contaminants (TACs) listed in the rule. Rule 1402 – Control of Toxic Air Contaminants from Existing Sources lists requirements for existing facilities with air toxic emissions. 

The Office of Environmental Health Hazard Assessment (OEHHA) establishes risk values for TACs.  The Scientific Review Panel (SRP) reviews and approves the methodologies used to develop these risk values, thereby finalizing these values for use by state and local agencies in assessing risk from exposures to TACs.  This approval is considered final action by the state.  The SRP met on April 22, 1998 and unanimously adopted the report proposing identification of diesel exhaust from internal combustion engines as a toxic air contaminant.  The California Air Resources Board subsequently identified particulate emissions from diesel-fueled internal combustion engines as a toxic air contaminant at its August 1998 meeting.  Diesel PM was not added to the Rule 1401 TAC list in this case in coordination with CARB in order to allow sufficient time to develop a comprehensive statewide diesel PM policy and programs, permitting guidelines, and guidelines for the AB 2588 Air Toxics Hot Spots Program.  As part of CARB’s diesel PM strategy, its Board has developed Air Toxic Control Measures (ATCMs) to address diesel PM from several sources, including the ATCM for Stationary Compression Ignition Engines that was CARB approved in February 2004 and that this District subsequently adopted.

As shown in Table I, the approved Cancer Potency (CP) value for diesel PM from internal combustion engines is 1.1E+00 (mg/kg-day)^-1.  This corresponds to a screening value of  1.04E-01 pounds per year per one in one million cancer risk.  The approved chronic reference exposure level is 5 μ g/m³.

  Table I – Risk Values

Diesel PM Sources

Diesel PM is produced when an internal combustion engine burns diesel fuel and is a complex mixture of gases and fine particles including many known or suspected cancer-causing substances.   Diesel fuel is widely used to power mobile sources such as large trucks, as well as stationary internal combustion engines throughout the AQMD.  Diesel has an advantage over other fuels in that it has a higher energy content than other fuels.  It is also desirable for use in emergency applications because it is more stable and less flammable than other fuels.  Areas that attract large sources of diesel exhaust include busy roads and freeways; rail yards; shipping docks; oil and gas production facilities; warehouse and distribution centers; and construction sites.  Most stationary sources of diesel exhaust in the AQMD are diesel engines used to power emergency generators and fire suppression equipment.  There are also a few non-emergency (prime) engines.  There are more than 10,000 permitted diesel-fueled internal combustion engines at over 5,300 facilities in the AQMD.      

Regulatory Options

Regulating diesel PM from internal combustion engines will affect many facilities and has potential implications for permitting, the AB 2588 program, and CEQA toxic thresholds.  Therefore, a variety of regulatory options are being considered and public input is being sought on the best options to address the many sources and risk levels associated with diesel PM. 

Three possibilities being considered at this time are adding diesel PM to the list of toxic air contaminants in Rule 1401, adding provisions to Rule 1470 – Requirements for Stationary Diesel-fueled Internal Combustion and Other Compression Ignition Engines, and/or developing a new rule to regulate facilities with high risk levels from diesel-fueled engines.  In addition, the AQMD staff is requesting public input on options for the implementation of the AB 2588 Toxics Hot Spots program guidelines for diesel-fueled engines.  Attached is a notification for a Public Consultation meeting to discuss the options. 

Rules 1401 and 1402 Notification Requirements

The addition of diesel PM to the list of TACs in Rule 1401 is one regulatory option being considered.  Rules 1401 and 1402 require notification to the Governing Board and affected industries prior to the addition of a new compound to the list of TACs in Rule 1401. In addition to the notification requirement, Rules 1401 and 1402 require that within 150 days of risk values for new TACs being finalized by OEHHA, the AQMD staff must bring proposed amendments to Rule 1401 to the Board, including an impact assessment for the affected facilities and preliminary estimates of Rule 1402 program impacts associated with the new values.  This report serves to satisfy the Board notification requirement in the event diesel PM is added to Rule 1401.