Author's note: If you have any diesel powered equipment in California, you are probably aware that diesel engines are now subject to substantial regulations. The following is a primer on the origins of diesel regulations in California.
Diesel particulate matter (PM) has been identified as the most significant toxic air contaminant in California; accounting for 70% of the ambient airborne cancer risk. In response to this, the State of California has enacted the most comprehensive and ambitious program to reduce ambient diesel pollution in history. Diesel emissions are a classic example of an un-internalized externality. The users of diesel engines gain the benefits of the device, yet do not pay the real costs in terms of health and welfare effects. This paper will discuss the legislative background, research on health and welfare affects, emissions inventories, verified emission control technologies and regulatory programs that have been enacted to reduce the risks associated with diesel PM.
Legislative Mandate and Research on Health and Welfare Effects
In 1983, the California Legislature passed Assembly Bill (AB) 1807: Health and Safety Code sections 39650-39674. AB 1807 mandated that the state conduct a two-step process to first identify TACs and then develop risk reduction programs to address the identified risks (1). In February 1998, the California Air Resources Board published its exposure and health risk assessments for diesel exhaust (2), (3). On April 22, 1998, the report was formally reviewed and approved by the Scientific Review Panel (SRP) (4). The approved report relied on over 30 human epidemiological studies and was considered the most exhaustive study the SRP had ever reviewed (4). The approved report characterized diesel exhaust as, “a complex mixture of gases and fine particles.” And found that nearly all of the particulate fraction of diesel exhaust was < 10µm and the 94% of the particulate fraction was < 2.5 µm. Particles of this size penetrate deeply into lung tissue and thus, are a regulated under the Clean Air Act (CAA). The report also estimated that PM accounts for 2000 premature deaths per year, 250 annual cases of lung cancer, decreased lung function in children, chronic bronchitis, increased respiratory symptoms and cardiovascular hospitalizations, aggravated asthma, lost work days, reduced visibility and contributed to global warming (5).
A Side Note to TAC Legislation Background: FRAUD
In 2009, nine months after a landmark decision by the Air Resources Board approving regulations to curb diesel exhaust in California, a firestorm erupted over the academic credentials of project leader Hien T. Tran, who conducted a crucial study on diesel pollution-related deaths. Tran admitted that he did not have the Ph.D. in statistics from the University of California, Davis, as he claimed during the hiring process for his position. In fact, Tran, in fact holds a Ph.D. from Thornhill University, a school that appears to be an internet diploma mill located, as one wag put it, in a UPS office in New York City.
Source: allgov.com, (http://www.allgov.com/usa/ca/departments/california-environmental-protection-agency/air-resources-board?agencyid=120) retrieved 1/9/15
Emissions Inventories and Projections
The 1998 estimated diesel PM emissions from on-road, off-road, portable and stationary sources was 28,000 tons/year (1). CARB models project 21,000 tons of emissions from those same sources in 2010 and 17,000 tons in 2020. This 40% reduction over 20 years was deemed to be insufficient to control the significant risk posed by diesel PM. CARB instead proposed a program that they believe will reduce diesel PM emissions by 75% (down to 7000 tons /year) in 2010 and 85% (down to 4200 tons /year) in 2020 (6). To achieve these reductions, CARB has proposed a three-pronged approach: New PM emissions standards for all new diesel engines, new retrofit requirements for existing diesel engines, and a new 15-PPM sulfur diesel fuel formulation (1).
Non-Road/Off-Road Emission Standards
13 CCR, 2425.1 was amended in 2004 to include more stringent non-road/off-road emission standards. This regulation provides standards for PM, NOx, NMHC + NOx and CO for new engines manufactured after 1996. Emission standards are categorized by tier, 1 through 4, and Horse Power (HP). Different tiers have different phase-in dates according to HP (7). Emission standards are summarized on the two tables below:
Table 1. Tier 1, Tier 2, and Tier 3 Exhaust Emission Standards (grams per kilowatt hour)
Table 2. Tier 4 Exhaust Emission Standards (grams per kilowatt-hour)
Both Tables from (7)
On–Road Heavy-Duty Diesel Emission Standards
California adopted tough new on-road heavy-duty diesel emission standards in October of 2001. These new standards limit PM emissions to 0.01 g/bhp-hr, NOx to 0.20 g/bhp-hr and NMHC to 0.14 g/bhp-hr for heavy-duty on-road diesel engines manufactured in 2007 and later. The new standards also removed the exemption for crankcase emissions from turbocharged diesel engines (8). These standards mirror Federal standards adopted by the EPA in 2000.
Approved Control Technologies
The State of California verifies Diesel Emission Control Strategies (DECS). Verified control strategies include Diesel Particulate Filters (DPF), Exhaust Gas Recirculation (EGR) with DPF, Diesel Oxidation Catalyst (DOC), emulsified fuels and Selective Catalytic Reduction (SCR) with DPF. Manufacturers must test DECS units to determine the level of effectiveness they provide and verify what engines the DECS is effective at controlling. Verified DECS are grouped by efficacy, the highest level of control is provided by Level 3 DECS, which reduce diesel particulates emissions by >85%. Level 2 DECS provide >50% reduction and Level 1 DECS provide >25% reduction. Systems that provide <25% reduction in PM emissions are not eligible for verification. A DECS can also be verified for NOx reduction. To be verified a system must reduce NOx by at least 15%. (9). CARB has estimated that diesel retrofits of portable, stationary and mobile sources can reduce statewide diesel emissions by over 8000 tons in 2010; with declining reductions in subsequent years as older engines that required retrofits are retired and replaced with newer, cleaner engines or alternative technology (10)
15-PPM Sulfur Reformulated Diesel
In 2004, the State of California approved amendments to 13 CCR, 2281, providing new standards for sulfur content (15-PPM) in diesel fuel sold in the state of California. This new diesel is called Ultra Low Sulfur Diesel (ULSD) and is required for both on-road and off-road applications. Sale of diesel fuel in excess of 15-PPM sulfur was prohibited after September 1, 2006. Previously, California had required 500-PPM sulfur diesel fuel, designated Low Sulfur Diesel (LSD). Both of these fuel formulations were a substantial improvement over previous un-regulated fuel formulations that often ranged from 2000 to 5000-PPM sulfur. Reduction of sulfur content in fuel directly reduces sulfur emissions and reduces acid rain. ULSD is also required for the implementation of DECS, many of which are not compatible by higher sulfur content fuel. The introduction of ULSD to the American market will also allow European vehicle manufacturers to import diesel fueled models without modifying them to accommodate higher sulfur fuel (11). Thus, an unintended consequence of this regulation may be to increase the number of diesel fueled light-duty cars and trucks on the road in the US.
Air Toxic Control Measures (ATCMs)
The Diesel Risk Reduction Plan was developed as a roadmap to achieve diesel emissions reductions. To address specific sources, ATCMs are developed by CARB staff and approved by the Office of Administrative Law (OAL). The following section will review ATCMs developed for stationary, portable and mobile sources of diesel PM.
Stationary Compression Ignition Engine ATCM
According to 1990 estimates, stationary diesel engines contribute less than 2% of diesel PM emissions. However, unlike most other emission sources in California, this source category was projected to remain stable or possibly increase over the next 20 years (1). As a result, substantial new regulations were approved to reduce the emissions from this category. On November 10, 2004 the OAL approved the Stationary Compression Ignition Engine ATCM and amended 17 CCR to include section 93115. On September 9, the OAL approved amendments to this same section. 17 CCR, 93115 seeks to reduce diesel PM emissions by limiting new and in-use standby emergency engine testing and maintenance operational time. It also sets more stringent PM emission standards for new diesel engines used for emergency standby, prime and agricultural applications. PM emissions and usage standards are summarized in the two tables below:
Table 3. New Stationary Diesel Engine > 50 HP (Installed and permitted on or after January 1, 2005)
Table 4. In-use Stationary Diesel Engine > 50 HP (Installed and permitted on or after January 1, 2005)
In addition, the ATCM required all operators to refuel with ULSD when it became available (September 1, 2006), limited CO, HC, NMHC, and NOx emissions for new engines, mandated regular engine maintenance and created new recordkeeping requirements. CARB estimates that the Stationary Compression Engine ATCM can reduce PM emissions by 500 tons/year in 2010 and 700 tons/year in 2020 (10).
Portable Compression Ignition ATCM
Portable compression ignition engines contribute approximately 7% of the diesel PM emissions produced annually in California. Without regulatory intervention, emissions were projected to shrink by approximately 50% in 2010 and 75% in 2020. On February 9, 2005, the Portable Compression Engine ATCM was filed with the Secretary of the State. The regulation became effective on March 11, 2005. This ATCM created a new section, 93116, in Title 17, CCR. Emergency amendments were approved by the OAL on December 27, 2006, and will be affective for 120 days. Permanent amendments are currently pending. The ATCM requires all portable engines to be comply with EPA/CARB Tier 1, 2, or 3 off-road engines standards by 2010. After 2010, all portable engines are required to meet diesel PM emission averages that become more stringent in 2013, 2017, and 2020 (12).
Table 5. Diesel PM emission standards for portable engines by date and HP group.
The Portable Compression Ignition ATCM was estimated to reduce annual PM emissions by 700 tons in 2010 and 252 tons in 2020 (10).
Transportation Refrigeration Unit (TRU) ATCM
On November 10, 2004, the Office of Administrative Law approved the Transportation Refrigeration Unit ATCM. This ATCM created a new section, 2477, in Title 13 CCR. TRUs are small portable engines used to heat or cool perishable food items during transportation. They are typically fitted to railcars, diesel semi trailers and delivery trucks. Most of these engines are small (9-36 HP) but they are numerous and often congregate in transportation facilities, distribution centers and trucks stops creating localized high levels of PM exposure for nearby receptors. This regulation requires new engines to meet stricter emission standards, older engines to be retrofit with particulate filters or use alternative, cleaner burning fuels (13).
Mobile Source ATCMs
As of May, 2006, California has adopted seven ATCMs to reduce PM emissions from mobile diesel sources. These include: transit busses, trash trucks, school bus idling, on-road truck idling, auxiliary diesel engines and diesel-electric engines operated on ocean-going vessels within California waters, mobile cargo handling equipment at ports and intermodal rail yards and on-road heavy-duty diesel vehicles operated by public agencies and utilities (12). In addition, CARB is currently developing rules to regulate private on-road heavy-duty diesel vehicles and all off-road diesel vehicles. All of these programs seek to reduce diesel PM emissions by changing behavior, as in the case of idling limits, or reduce emissions by setting emission standards for new engines and require older engines to retrofit with approved control technologies. CARB estimates that mobile source programs can reduce diesel emissions by over 10,000 tons statewide in 2010 (1).
Diesel PM is a long-standing air quality issue in California. The goals of the Diesel Risk Reduction Program are lofty and its execution will be challenging. Currently the two most substantial sources, private on-road heavy-duty diesel fleets and off-road fleets, are in the rule making process. Both of these sources have ample resources and substantial lobbying power. The success of the program rides on the ability of CARB staff to hold their ground and create real and substantial reductions of emissions from these sources. California is the most populous state in the nation. The high population creates many environmental challenges and often forces California to be on the leading edge of environmental regulations. The high population also makes California a very lucrative market and allows California to pass regulations that are “technology forcing.” If California can successfully implement the Diesel Risk Reduction Program, other states and nations will soon follow suit.
1. Risk Reduction Plan to Reduce Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles (October, 2000) retrieved March 30, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/diesel/documents/rrpFinal.pdf
2. Report to the Air Resources Board on the Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, Part A, Exposure Assessment (April 22, 1998) retrieved March 30, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/toxics/dieseltac/part_a.pdf
3. Report to the Air Resources Board on the Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, Part B, Health Risk Assessment for Diesel Exhaust (May, 1998) retrieved March 30, 2007 from the California Air Resources Board Website: ftp://ftp.arb.ca.gov/carbis/regact/diesltac/partb.pdf
4. Findings of the Scientific Review Panel on The Report on Diesel Exhaustas adopted at the Panel’s April 22, 1998, Meeting. Retrieved March 30, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/toxics/dieseltac/combined.pdf
5. Health Effects of Diesel Exhaust Particulate Matter (March 1, 2006) retrieved March 30, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/research/diesel/dpm_draft_3-01-06.pdf
6. Report to the Air Resources Board on the Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, Appendix III, Mobile Diesel-Fueled Engines: Report on the Need for Further Regulation of Particulate Matter Emissions (October, 2000) retrieved March 30, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/diesel/documents/rrpapp3.PDF
7. Off-Road Compression-Ignition (Diesel) Engines and Equipment Documents (April 20, 2005) retrieved April 10th, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/msprog/offroad/orcomp/documents.htm
8. Heavy-Duty Truck and Bus Engines (2001) retrieved April 10th, 2007 from the Diesel Net Website: http://www.dieselnet.com/standards/us/hd.html#y2007
9. Verified Technologies (February 20, 2007) retrieved April 10th, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/diesel/verdev/vt/vt.htm
10. Report to the Air Resources Board on the Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, Appendix II, Stationary and Portable Diesel-Fueled Engines: Appendix to the Diesel Risk Reduction Plan (October, 2000) retrieved March 30, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/diesel/documents/rrpapp2.PDF
11. Ultra-low sulfur diesel (March 30, 2007) Retrieved from the Wikipedia Website on April 10, 2007: http://en.wikipedia.org/wiki/ULSD
12. Fequently Asked Questions Regarding the Stationary Diesel Engine ATCM (May 8, 2006) retrieved April 10th, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/diesel/documents/atcmfaq.pdf
13. Transport Refrigeration Units (April 5, 2007)retrieved April 10th, 2007 from the California Air Resources Board Website: http://www.arb.ca.gov/diesel/tru.htm