Managing Carbon Monoxide Pollution in Meteorological and Topographical Problem Areas (2003) / Chapter Skim
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1. Ambient Carbon Monoxide Pollution in the United States
1. Ambient Carbon Monoxide Pollution in the United States
Pages 16-71
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From page 16... ...
CO was and still is the most recognizable indicator of incomplete combustion and has Tong been viewed as one of the most fundamental indicators of ambient air quality. When continuous monitors were first installed in some cities in the early 1960s, maximum 8-hour average concentrations in excess of 30 parts per million (ppm)
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From page 17... ...
The committee's statement of task was as follows: An NRC committee will assess various potential approaches to predicting, assessing, and managing episodes of high concentrations of CO in meteorological or topographical problem areas. The committee will consider interrelationships among emission sources, patterns of peak ambient CO concentrations, and various CO emissions control measures in such areas.
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18 To to Cal CD Ct Cd o V o 50 At CQ Ct au · _4 CQ .
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19 ¢ r~ r~ o _ a~ _ _ ~ ~ _ o Z _ ~ ~ _ r~ o rn cr.
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. Assessing the effectiveness of CO emissions control programs, including comparisons among areas with and without unusual toco~rachi-r -en- ~rcal or meteorological conditions.
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The findings associated with the progress on reducing CO violations and vulnerability to future violations are relevant to CO episodes in other meteorological and topographical problem areas. The committee recommended that there be improvements to local emissigns controls, including vehicle emissions inspection and maintenance (I/M)
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From page 22... ...
The emphasis on controlling cold-start emissions through plug-ins is generally limited to Fairbanks and likely does not translate well to the lower 48 states. ~ its interim report, the committee noted that officials with the borough argued that Fairbanks should be granted an exemption from the Clean Air Act with regard to the ambient CO health standards because of its extreme meteorological and topographical conditions.
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From page 23... ...
Chapter 2 describes the meteorological and topographical conditions that foster pollution episodes in CO problem areas. Temperature inversions, Tong-term meteorological trends, temporalpatterns of CO concentrations, end vulnerability of areas to future exceedances are discussed in detail.
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To meet the city's goal of continually improving air quality as described in the City of Fort Collins Air Quality Action Plan (2001) , the city used their nonattainment status to pursue emissions control strategies that are not traditionally implemented in attainment areas.
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From page 25... ...
Vulnerable Areas and the Form of the CO Standard The form ofthe CO standard, where a violation occurs upon the second and all subsequent exceedances in a calendar year, contributes to the diff~culties that meteorological and topographical problem areas have in attaining the standard. A significant probability of an exceedance exists with the current attainment test because of the stochastic nature of ambient air pollutant concentrations (Gibbons 2002~.
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From page 26... ...
Conformity requirements were made more rigorous in the CAAA90 and in the regulations EPA issuedin 1993 to implement the requirements (40 CFR § 51 and 93 tI9933~. The CAAA90's conformity mandate requires that transportation plans, programs, and projects in nonattainment or maintenance areas funded or approved by the Federal Highway Administration (FHWA)
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From page 27... ...
Also, traffic-simulation models can be combined with instantaneous emissions at the microscale level to predict emissions inventories and to assess queuing and traffic flow along specific roadway segments or at specific intersections. Proposed projects to change traffic patterns are often analyzed by starting with the three intersections with the highest traffic volumes and poorest level-of-serv~ce to determine if CO problems exist, and then modeling other intersections where capacity is equaled or exceeded.
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From page 28... ...
EPA (2002a) reports that the national average ambient CO concentration in 2001 was 62% lower than it was in 1982 and 38°/O Tower than it was in 1992.
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From page 29... ...
A downward trend in concentrations also can be seen in Figure 1-3, which shows the decline in the nationwide composite average of annual second-highest 8-hour CO concentrations from 1978 to 1997. The smoother decline of the composite average is a result of the large number of sites included.
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From page 30... ...
The study concluded that, although CO concentrations at the microscale sites are often higher than concentrations found at larger-scare monitoring sites (sites located in extended urban areas and more rural areas) , CO concentrations at microscaTe sites are declining at the same rate as concentrations recorded at monitors representing larger regions.
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From page 31... ...
SOURCES OF CO EMISSIONS National Inventory The major categories of CO emissions sources include transportation (mobile sources) , industrial processes, nontransportation fuel combustion (which includes stationary and area sources)
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and nonroad engines and vehicles (26%~. The remaining CO emissions are from area and point sources, including fuel combustion and industrial processes.
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From page 33... ...
substantial inaccuracies in estimates of fleet emissions and effectiveness of control strategies for on-road vehicles. Regional Inventories In urban areas, mobile sources tend to contribute more to the mix of emissions than indicated by the national average.
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On-road vehicles 49,989 51.3 Light-duty gas vehicles and 27,382 28.1 motorcycles Light-duty gas trucks 16,115 16.5 Heavy-duty gas vehicles 4,262 4.37 Diesels 2,230 2.29 Nonroad engines and vehicles 25,162 25.8 Recreational 3,616 3.71 Lawn and garden 11,116 11.4 Aircraft 1,002 1.03 Light commercial 4,259 4.37 Other 5,169 5.30 Miscellaneous 9,378 9.62 Slash or prescribed burning 6,152 6.31 Forest wildfires 2,638 2.71 Other 588 0.615 . Total 97,441 Source: EPA 2001a.
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From page 35... ...
35 o a' to 'e to ¢ cd ~ of CQ ~ .~ 'e v ~ of A A, o oh g .—~ do I)
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From page 36... ...
Such conditions mean that local power-plant emissions released well above the inversion height likely do not mix with ambient air at the monitor height and, thus, do not contribute to the high CO concentrations recorded at monitoring sites. In addition, some CO sources included within these regional inventories might be located at great distances from monitors and might not contribute to local exceedances.
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From page 37... ...
. These milestones, which have led to large reductions in CO and other pollutant emissions, include national standards for tailpipe emissions, new vehicle technologies, and clean fuels programs as well as state and local vehicle emissions I/M programs and transportation management programs.
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38 Managing CO in Meteorological and Topographical Problem Areas eluding wood burning, lawn and garden equipment, and natural sources, such as wildfires. It should be noted that CO is produced not only through incomplete combustion but also from the thermal decomposition of CO2,
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From page 39... ...
In addition, operators of lawn and garden equipment may experience high personal exposures to CO. HEALTH EFFECTS OF CO Clinical and Epidemiological Studies of CO Effects The health effects of CO have been assessed through controlled exposure of human volunteers and a growing body of community epidemiological studies (EPA 2000a)
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From page 40... ...
The CO ambient-air health standards set by EPA are intended to keep COHb concentrations for nonsmokers below 2% and protect the most susceptible members of the population. The goal of both the 1-hour and 8hour standards is related to maintaining COHb concentrations below this level.
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From page 41... ...
2000~. Generally, in otherwise healthy people, headache develops when COHb concentrations reach 10%; tinnitus (ringing in the ear)
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From page 42... ...
In patients with known coronary artery disease, COHb concentrations as Tow as 3% exacerbate the development of exercise-induced chest pain (AlIred et al.
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From page 43... ...
The correlation of these effects with ambient CO occurred at concentrations below the NAAQS. The study was inconclusive regarding the effects of PM~o and nitrogen dioxide; however, the lead author of the study cautioned that the real culprit might be other pollutants, such as PM and some air tonics, that are coemitted with CO in tailpipe emissions (Ritz 2002~.
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(2002) recently used computerized death-certificate data maintained by the Centers for Disease Control and Prevention to evaluate the influence of national vehicle emissions controls on unintentional motorvehicle-related CO deaths between 1968 and 1998.
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From page 45... ...
However, these documents do not separate the health benefits of CO control from other criteria pollutants. In the 1997 report, the control of PM and CO under the Clean Air Act is estimated to reduce the mean number of hospitalizations for congestive heart failure by 39,000 annually in 1990 compared with a no-control scenario (EPA 1997a)
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From page 46... ...
46 Managing CO in Meteorological and Topographical Problem Al reas environments and shows how congested roadways, street canyons, tunnels, underpasses, drive-up facilities, end perking garages canproduce exposures well above ambient conditions. Relationship of Indoor to Ambient Concentrations Most people spend a majority oftheir time indoors; this is particularly true in cold climate areas during winter, when ambient CO concentrations tend to be highest.
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From page 47... ...
in combination with urban background concentrations, localized sources may subject some individuals to very high CO concentrations. Spatial Distribution of CO Studies that demonstrate the spatial end temporal distribution of CO are beneficial in assessing the potential human exposure to CO and other polJutants from vehicle emissions.
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From page 48... ...
These studies are helpful to air pollution control agencies for evaluating their ambient air monitoring networks, characterizing pollutant concentrations over the entire saturation study area, and locating hot spots or high pollutant impact points. Personal and indoor monitoring could be incorporated into such studies to relate ambient concentrations to personal exposure.
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; 7 _ i 147\ l ar ·37 J I ~ / ~8 HOLL~WOO0~/ tfA-~=NA \~2 - 31,/~0WNTOWN I== ~L I- ~ _ _' END i. 2 or ~ A ~ R POR T l 1 ~ | / lS SAN a~P`NARDINO | 1 R EDL AN DS I .~4 1' ~ _ 16,' Rl VERSIDE FIGURE 1-8 Maximum 8-hour average CO concentrations in We South Coast Air Basin for 1956-1967.
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i''. FIGURE 1-9 Maximum 8-hour average CO concentrations in the South Coast Air Basin in 2000.
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From page 52... ...
Association of CO Emissions to Other Emissions Automobile exhaust is a complex mixture of compounds, some of which are classified as criteria air pollutants and others as hazardous air pollutants (HAPs) or "air tonics." The correlation of CO with PM2 s and some air taxies is especially strong for gasoline-powered light-duty vehicles (LDVs)
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From page 53... ...
shows the overlap among the highest-emitting 10% of vehicles randomly Typical numbers reported in the literature (usually obtained from measurements of in-use vehicles) show that 50-60% of on-road LDV exhaust emissions are produced by about 10% of LDVs (NRC 2001~.
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. The Multiple Air Toxic s Exposure MATES-I study in the South Coast Air Basin of California (SCAQMD 2000b)
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From page 55... ...
Air Toxic (%) Acetaldehyde 70 Lead compounds 23 Acrole~n 39 Manganese compounds 1.5 Arsenic compounds 0.6 Mercury compounds 4 Benzene 76 Methyl tertia~y-butyl 1,3-Butadiene 60 ether (MTBE)
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From page 57... ...
Ambient CO Concentrations and Other Pollutants The relationships among ambient concentrations of CO, air tonics, and PM are complex and are affected by differences in direct pollutant sources and by atmospheric processes that create chemical sinks and secondary products. Figure 1-12 (above)
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From page 58... ...
found that these concentrations peak in the summer and fall in the South Coast Air Basin. The peak is delayed because increased vertical mixing and dispersion occurs during the summer, which reduces the concentrations of these pollutants.
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From page 59... ...
in California's South Coast Air Basin in 1996. Source: CARE 1999.
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From page 60... ...
, high PM2 5 and high CO concentrations occur in response to prolonged winter temperature inversions. The inversions can last 2 to 3 weeks without a break, as was the case during these PM2s exceedances.
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From page 61... ...
. o 5 10 15 20 25 30 35 40 45 50 PM2.5 ,ug/m3 FIGURE 1-15 Correlation of daily average CO and PM2 5 concentrations at the state building, Fairbanks, Alaska, November 2000 to February 2001.
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From page 62... ...
scale (Carter 1998) of CO is 0.065 g of O3 per gram of CO emitted, which can be compared to the MIR of exhaust emissions from vehicles fueled with two gasolines representative of California reformulated gasoline (testing conducted during the Auto/OiT Air Quality Improvement Research Program)
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From page 63... ...
Using CO As an Indicator of Other Pollutants In urban environments, CO can serve as an indicator of motor vehicle emissions from gasoline-fueled vehicles. The observed spatial and temporal variability of CO shows that the effects of motor-vehicle pollution are heterogeneously distributed in urban areas and that CO can be a useful gauge of long-term human exposure to other pollutants of concern, including certain mobile-source air tonics.
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From page 64... ...
The precise correspondence of CO and other organic vehicle emissions depends on the fuel used (including the presence or absence of a fuel oxygenate, the actual oxygenate used, end the aromatic content ofthe fuel) and onboard emissions control technologies and engine conditions (i.e., cold start, hard acceleration, etc.~.
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From page 65... ...
emitted from LDVs will still be observed over distance scales corresponding to travel times of the pollutants of approximately a half-Tife or less (see Figure 1-14~. EQUITY CONSIDERATIONS IN THE SPATIAL DISTRIBUTION OF AMBIENT CO Because CO levels are not evenly distributed, exposure to CO within the population will vary.
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From page 66... ...
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From page 67... ...
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From page 68... ...
68 · lo;, 1 EM no ~ V ~ $Ct C)
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From page 69... ...
The order was related to Title VI of the Civil Rights Act of 1964 and required federal agencies "to achieve environmental justice by identifying and addressing disproportionately high and adverse human health and environmental effects, including the interrelated social and economic effects of their programs, policies, and activities on minority populations and low-income populations in the United States." The order also stipulated that in reviewing other agencies' proposed actions under Section 309 of the CAA, "EPA must ensure that the agencies have fully analyzed environmental effects on minority communities and low-income communities, including human health, social, and economic effects " (EPA 1 998a)
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From page 70... ...
. According to EPA, fair treatment requires that EPA conduct its "programs, policies, and activities that substantially affect human health and the environment in a manner that ensures the fair treatment of all people, including minority populations andlor low-income populations" and that EPA ensure "equal enforcement of protective environmental laws for all people, including minoritypopulations and/or low-income populations" (EPA 20016~.
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From page 71... ...
In addition to providing an important impetus for the continuation of efforts to eliminate CO exceedances, these results suggest a need for monitoring and personal exposure research programs designed to more fully characterize the distribution of CO and other mobile-source-related pollutants.
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