California Air Resources Board

Background

Diesel internal combustion (IC) engines are often used for constant load applications such as construction equipment, vehicles, and powering equipment at manufacturing plants. Emergency standby diesel IC engines are typically used for back-up electric power generation or for pumping water during a fire or flood. These emergency standby IC engines make up the majority of the total number of non-vehicular diesel engines in California, and are widely dispersed throughout the state.

Diesel Particulate Matter (DPM) is the particulate component of diesel exhaust, and has been identified as a Toxic Air Contaminant (TAC) by CARB based on its potential exposures and health concerns.  Epidemiological studies strongly suggest a relationship between occupational diesel exhaust exposure and lung cancer. A number of adverse acute and chronic effects have also been associated with exposure to diesel exhaust. 

Air Districts perform health risk assessments for air pollutants from non-vehicular diesel IC engines, and will generally solely focus on DPM. Health risk assessments characterize potential cancer and noncancer health impacts to the public, and are used in various Air District air toxics programs. If these health impacts exceed the Air District’s health risk thresholds, the owner or operator must notify exposed members of the public and may be required to reduce those health impacts.

To help Air Districts prepare gas station health risk assessments to meet the requirements of Assembly Bill 2588 Air Toxics “Hot Spots” Act, the California Air Pollution Control Officer’s Association (CAPCOA) and the California Air Resources Board (CARB) have developed a technical guidance document and screening tool to assist Air Districts in performing screening health risk assessments.

Non-Vehicular Diesel Engine Risk Assessment Guidelines Document

• Technical Guidance (pdf)

Non-Vehicular Diesel Engine Risk Assessment Screening Tool

• Screening Tool (.zip with .exe)
• User Guide (pdf) 

Additional Resources

• AB 2588 Air Toxics “Hot Spots”
• "Hot Spots" Risk Assessment
• AB 2588 District Prioritization Scores and Risk Threshold Levels
• AB 2588 "Hot Spots" Facility Prioritization
• Health Risk Assessment
• Office of Environmental Health Hazard Assessment (OEHHA) Air Toxics Hot Spots Program Guidance Manual for the Preparation of Risk Assessments (February 2015)
• Hotspots Analysis and Reporting Program (HARP)
• Speciation Profiles Used in CARB Modeling
• Portable Equipment Registration Program (PERP) 
• Public Safety Power Shutoff (PSPS) Events