EPA Proposed Rule “National Ambient Air Quality Standards for Particulate Matter”: Urban Air Initiative Comments

August 30, 2012

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(Urban Air Initiative) From a letter to the Administrator of the Environmental Protection Agency, August 30, 2012: Urban Air Initiative (UAI) appreciates this opportunity to comment on the Agency’s proposal to address one of our most dangerous and costly health threats, urban fine particulate matter, known as PM2.5.
Taking the proper steps to reduce fine and ultrafine particulates, as well as black carbon (BC), would also lead to significant reductions in related harmful constituents that coat or are absorbed by the particles, toxic compounds such as polycyclic aromatic hydrocarbons and quinones (PAHQs), and would produce substantial health and climate change benefits.1 UAI is a non-profit 501(c) (4) corporation dedicated to the identification, research, and public education of cost effective methods of improving the quality of urban air. UAI’s primary goal is to reduce harmful emissions from ubiquitous gasoline exhaust in our largest cities, which are responsible for billions of dollars in health costs each year, and are of great concern to tens of millions of Americans that belong to the most susceptible and vulnerable segments of
our population.
SUMMARY OF COMMENTS.
While UAI commends the Agency for addressing the issue of fine particle pollution, at 38899 of the rule, EPA notes that a great deal of new science on PM health effects has been published since mid-2009, the Integrated Science Assessment’s cut-off date. UAI understands that the Agency will pay careful consideration to “studies that may be submitted during the comment period…in order to ensure that, before making a final decision, the Administrator is fully aware of the new science that has developed since 2009.” Toward that end, UAI’s comments will focus on several key areas where it believes EPA’s analysis falls short of incorporating published studies and new science, and/or connecting the relationship between PM constituents and their human health effects. UAI believes that the primary areas in need of additional consideration prior to releasing the final rule are:
1. Particle size and composition are interconnected and have enormous impact on human health.
2. Gasoline exhaust is the primary source of urban primary and secondary PM, BC, and PAHQ toxics.
3. PAHQs are known toxics, have proven and serious health effects, and should require no additional epidemiological proof for EPA to act.
4. Ultrafine particles, PAHs, and BC are inextricably tied to gasoline composition, and their emissions will increase in urban areas if fuel quality improvements do not complement advanced engine designs.
5. Cost effective and technologically available methods of improving fuel quality exist.
6. EPA has clear statutory authority, and some experts say the legal obligation, to improve gasoline quality standards.
SALIENT FACTS.
1. In addition to size distinctions (e.g., PM2.5 = 2.5 micrometers (μm) or smaller in aerodynamic diameter), experts also distinguish between primary and secondary PM.
2. BC is a “significant fraction of primary PM”.
3. EPA defines BC as an SLCF (Short-Lived Climate Forcer), and “the most strongly lightabsorbing component of PM2.5”… This means that actions taken to reduce BC constituents in direct [primary] PM2.5 will have almost immediate effects on climate change”. [EPA RIA, p. 6-34]
4. Mobile sources are responsible for 69% of all non-wildfire BC in the US. [EPA Draft Report to Congress].
5. Gasoline aromatic hydrocarbons are significant contributors to the formation of secondary organic aerosols in the atmosphere and resulting particulate formation. Researchers from the University of Colorado–Boulder and NOAA found that 80+% of the SOAs in Los Angeles, CA, came from gasoline exhaust. [March 2012]
6. “In urban areas, vehicular emissions constitute the majority of the primary particles in the atmosphere…Shortly after their emission from the tailpipe, highly concentrated gas vapors experience super-saturation due to rapid cooling in the atmosphere, which causes them to nucleate or condense onto the pre-existing particles, thereby creating a chemically complex aerosol…PAHs are semi-volatile organic compounds and they exist in both gas and particle phases. Given the increased toxicity of these semi-volatile species, efforts should be made to reduce their emissions from newer vehicles, including reductions in their gas-phase precursors formed during the combustion process.” [Ning, Sioutas, University of Southern California, 2010]
7. PAHs are toxic, carcinogenic, and mutagenic. They coat the PM2.5 and ultrafine particles and are absorbed by the highly porous BC particles. The tiny particles then act as effective carriers of the PAHQs, and enable them to penetrate deeply into humans’ lungs, enter the bloodstream, and get deposited into organs and cellular structures. PAHs cause a wide range of health disorders, including cancers, heart disease, and asthma and other respiratory conditions. PAHs are also one of the most omnipresent endocrine disruptor compounds. Experts have identified them as especially damaging to the fetus and young children, and other susceptible groups such as the elderly, asthmatics, and diabetics.
8. Congress gave EPA clear authority to reduce toxic emissions from gasoline in the 1990 Clean Air Act Amendments, including explicit instructions to reformulate gasoline by reducing and/or eliminating aromatics and other precursors of PM2.5 and PAHs.
9. Improving gasoline composition is one of the most cost effective means of reducing particleborne toxics and BC emissions. For example, E30+ blends reduce particle number, particle mass, and BC by 30 – 45%, according to recent Ford Motor Company research. Recent studies show that ethanol’s superior octane properties make mid-level ethanol blends a cost-effective substitute for hydrocarbon aromatics as gasoline octane enhancers.
PARTICLE SIZE AND COMPOSITION ARE INTERCONNECTED AND HAVE ENORMOUS IMPACT ON HUMAN HEALTH.
...
GASOLINE EXHAUST IS THE PREDOMINANT SOURCE OF URBAN PRIMARY AND SECONDARY PM, ULTRAFINE PARTICLES, BC, AND PAHQ TOXICS.
UAI believes that EPA’s regulatory approach is in urgent need of rebalancing, as it has disproportionately relied upon stationary and diesel emissions controls6, and has largely overlooked the significant role played by gasoline exhaust in our largest cities, which is where the vast majority of Americans live and work. In addition to its important role as a source of the powerful warming agent BC, gasoline exhaust represents the highest volume, most ubiquitous, and pervasive source of ambient PM, UFPs, and the PAHQ toxics in the urban environment. UAI experts’ analysis of the scientific literature has confirmed that the gasoline aromatic compounds, which by virtue of their physical and chemical properties are extremely difficult to combust, are the primary source of both the toxic PAHQs, and the particles which
carry them to humans’ lungs in urban environments, and responsible for billions of dollars of premature mortality and morbidity costs. The incomplete combustion of aromatics sets in motion a virtually inseparable chain reaction of semi-volatile organic compounds, UFPs, PAHQs, PM2.5, and BC emissions that makes urban air so dangerous for tens of millions of Americans. Consequently, UAI believes that the single most important action the EPA can take to protect the public health and welfare is to set higher standards for gasoline quality.
Attachment B provides more background and links to support this contention, but several of them are worth mentioning here.
1. Funded by CARB, NOAA, and the National Science Foundation, University of Colorado-Boulder researchers recently determined (March 2012) that 80+% of the secondary organic aerosols (SOAs, or secondary PM) in the Los Angeles basin were attributable to gasoline, not diesel, exhaust. http://www.colorado.edu/news/releases/2012/03/02/gasoline-worse-diesel-when-itcomes-some-types-air-pollution
2. A February 2009 MIT study by Chan et al., “Understanding Secondary Organic Aerosol (SOA) Formation from Lower-Volatility Precursors: Photooxidation of Naphthalene and Alkylnaphthalenes”, stated that “ After 3 h of photooxidation, PAHs and n-alkanes can account for up to 86% of the SOA, or all of the “unexplained” SOA”. (Slide 12)
3. In October 2010, Honda Motors research scientists found that a substantial amount of PM emissions are produced by gasoline engines, and that “all of the additional PN (particle number) is considered a PAH, with a high boiling point or soot. The higher the boiling point hydrocarbon added, the more the PN increases. This trend is particularly notable with aromatic substances.” Honda concluded that since PM is a risk to both human health and global warming, “PM
emissions from gasoline engines can be significantly reduced by improving the quality of fuels around the world.” [SAE-2010-01-2115]
4. In its December 2011 Appendix P to the LEV III ruling, CARB stated that “Although diesel engines are known major contributors to PM emissions, recent studies show that gasoline engines also play a key role”, and cited a 2010 Iizuka, et al. study. This study cited aromatics content as an even more important factor than distillation, and recommended replacement of aromatics with ethanol (slide 32). Supra, p. 88
5. In the same document, on p. 123, CARB states: “The results of this analysis indicate that EC [elemental carbon, used interchangeably with BC] accounts for approximately 70 percent of the PM mass emissions from gasoline-powered LDV. This result is in stark contrast to lower EC/PM ratios reported by others (U.S. EPA 2008). The rising EC/PM ratio observed in the newer vehicles tested in this study indicates that the reductions in EC emissions may not follow PM
mass reductions…the ARB is still maintaining the importance of the particle counting alternative and is pursuing an active study program on particle number measurement as an alternative to the filter-based method”.
6. A May 2009 UCLA/CARB study found “peak levels of ultrafine particles (UFP) immediately adjacent to the freeway, but we found high concentrations persisted for up to 1.5 miles downwind of the freeway during the pre-sunrise hours.” Other pollutants, including “particle-bound polycyclic aromatic hydrocarbons, also extended far from the freeway during the pre-sunrise hours,” a time when most people are in their homes. http://www.ph.ucla..edu/pr/newsitem061009.html
The sixth study referenced above seems to contradict the Agency’s statement at 38921-38922: “Internal combustion engines and, therefore, roadways are a notable source of ultrafine particles, so concentrations of these particles near roadways are generally expected to be elevated. Concentrations of ultrafine particles have been reported to drop off much more quickly with distance from roadways than fine particles (U.S. EPA, 2009a, p. 3-84).”
Black Carbon, Mobile Sources, and PAHs. In a 2010 Sustainability article, Sierra Nevada Research Institute, et al. published “Black Carbon’s Properties and Role in the Environment: A Comprehensive Review.”7 The paper does an excellent job of elaborating on BC’s relationship with PAHs, and its subsequent impact on both global warming and health effects. The authors note that “The emission and transport of BC in the environment is also associated with the fate of other organic substances, particularly polycyclic aromatic hydrocarbons (PAHs), whose isomers can be utilized to
trace the sources of BC in soils and sediments.” Fossil fuel BC is fully depleted in radiocarbons (14C), whereas biomass BC is not. This makes BC a useful tool to measure fossil fuel combustion emissions. In addition, scientists can reliably use PAH isomers to identify the source of the BC, which in most U.S. cities is predominantly gasoline exhaust. READ MORE and MORE (Attachment A- EPACARB and other studies) and MORE (Attachment B - UAIPMrulegasolinemajorsource final) and MORE (Attachment C UAI PM Rule Comments) and MORE (Urban Air Initiative) and MORE (Urban Air Initiative Responses to US House Energy and Commerce Stakeholder Comment regarding Greenhouse Gas Emissions and Other Environmental Impacts of the Renewable Fuels Standard)