Ozone Air Quality Standards Research Articles

Clean air in Europe for all: A call for more ambitious action.

Clean air in Europe for all: A call for more ambitious action.

Long-term Baseline Ozone Changes in the Western US: A Synthesis of Analyses

Quantification of the magnitude and long-term changes of ozone concentrations transported into the US is important for effective air quality policy development. We synthesize multiple published trend analyses of western US baseline ozone, and show that all results are consistent with an overall, non-linear change – a rapid increase (~5 ppb/decade) during the 1980s that slowed in the 1990s, maximized in the mid-2000s, and was followed by a slow decrease (~1 ppb/decade) thereafter. This non-linear change accounts for ~2/3 of the variance in 28 published linear trend analyses; we attribute the other 1/3 of the variance to unquantified autocorrelation in the analyzed data sets that result primarily from meteorologically-driven interannual ozone variability. Recent systematic changes in baseline ozone at the US West Coast have been relatively small - the standard deviation of the 2-year means over the 1990-2017 period is 1.5 ppb. International efforts to reduce anthropogenic precursor emissions from all northern mid-latitude sources could possibly reduce baseline ozone concentrations, thereby improving US ozone air quality. Implications Statement Ozone is an air pollutant with significant human and ecological health impacts. Air masses transported into the western US from over the Pacific Ocean carry ozone concentrations that are, on average, a large fraction of the US health standard. The US EPA policy assessment conducted for the recent review of the ozone National Ambient Air Quality Standard (NAAQS) found that 2016 regional average MDA8 ozone concentrations in the western US maximized in summer at ~52 ppb and that ~40 ppb of that maximum was contributed by ozone of natural and transported anthropogenic contributions. Thus, quantifying these trans-boundary background ozone concentrations has been identified as an important issue for a complete understanding of US air quality (e.g., see discussion in Introduction of Jaffe et al., 2018). Published analyses of temporal trends of these transported ozone concentrations vary widely, from early reports of increases to more recent reports of decreases. We show that the long-term ozone changes have been nonlinear, with substantial concentration increases (as large as ~5 ppb/decade) before the mid-2000s when a maximum was reached, followed by a small decrease of ~1 ppb/decade) thereafter. Superimposed on the overall changes is significant interannual variability that makes accurate determination of systematic trends over decade-scale time periods uncertain. The end of the previously increasing trends, and the recent decreases in transported ozone concentrations is good news for US air quality, as it eases the difficulty of achieving the ozone air quality standard.

CABOT-O3: An Optimization Model for Air Quality Benefit-Cost and Distributional Impacts Analysis.

Macpherson et al. (2017) presented a mathematical programming model that identifies minimum-cost control strategies that reduce emissions regionally to meet ambient air quality targets. This project introduces the Cost And Benefit Optimization Tool for Ozone (CABOT-O3), which extends the previous model by updating emissions and air quality relationships, adding a health impacts module, and quantifying distributional impacts. The tool draws upon source apportionment photochemical air quality modeling to characterize the contribution of emissions reductions to ambient ozone concentrations across the contiguous United States. The health impacts analysis module estimates the change in the number and economic value of premature deaths using modeled changes in ozone levels resulting from the application of emission control strategies. These extensions allow us to evaluate strategies to attain ozone air quality standards at minimum cost or to maximize net benefit, while assessing the change in the distribution of health impacts. In a case study applied to stationary pollution sources, we find that, when compared to minimizing costs to meet a uniform ozone standard, maximizing net benefits results in greater emissions and ozone concentration reductions in some parts of the country and fewer in others. Our results highlight potential equity-efficiency trade-offs in designing air quality policies.

Synoptic classification of meteorological patterns and their impact on air pollution episodes and new particle formation processes in a south European air basin

A circulation classification technique based on daily sea level pressure fields was applied to classify homogeneous synoptic types in the period 2001–2019 for the Iberian Peninsula (IP). The main synoptic meteorological patterns (SMP) were thus discriminated and then validated by the analysis of meteorological variables and atmospheric stability parameters registered in the Madrid air basin in the year 2015. Then, their utility to characterize atmospheric processes like air pollution episodes or new particle formation in the study area was evaluated. Specific SMP clearly influenced wind circulations and turbulent processes at different spatial scales. At regional scale they contributed to discriminate among pollution episodes giving rise to exceedances of air quality standards for particulate matter, nitrogen dioxide and ozone at monitoring stations. For instance, two of the resulting SMP, characterized by the presence of intense high pressure systems close to the IP and strong atmospheric stability in winter and autumn, produced slightly different urban high-pollution episodes in this region. The highest mean levels of nitrogen dioxide, PM10 and PM2.5 (particles lower than 10 and 2.5 μm, respectively) and of ultrafine particles number concentration registered at different urban traffic, urban background and suburban stations, happened during these specific SMP. Likewise, most new particle formation events took place during two other SMP, which mainly occurred in spring and summer. One of them was characterized by high values of solar irradiance and surface temperature, which favour nucleation processes. The highest mean levels of ozone were also registered at the urban and rural stations during this SMP. The other one represented an unusual meteorological scenario in the IP compared to the others obtained in the study, with high pressures displaced northwest producing relatively high values of surface wind speed. This fact reduced the condensation sink and favoured new particle formation in the midday period. In short, this methodology that considers a large amount of interconnected variables can be very useful for characterizing atmospheric situations that have a strong influence on atmospheric pollution processes in other regions.

Does Environmental Policy Affect Income Inequality? Evidence from the Clean Air Act

This paper quantifies the impact of environmental policy on income inequality. We focus on the Clean Air act and the National Ambient Air Quality standards for fine particulate matter and ozone. Using a matched difference-in-differences estimator, we find evidence that both standards increased inequality in market income and a measure of income that deducts per-capita air pollution damage from adjusted gross income. While pollution standards can reduce pollution levels and thus result in significant environmental benefits in aggregate, our findings suggest that these standards appear to distort the distribution of economic resources in complex, and at times unfortunate, ways.

Ozone exposure is associated with acute changes in inflammation, fibrinolysis, and endothelial cell function in coronary artery disease patients

BackgroundAir pollution is a major risk factor for cardiovascular disease, of which ozone is a major contributor. Several studies have found associations between ozone and cardiovascular morbidity, but the results have been inconclusive. We investigated associations between ozone and changes across biological pathways associated with cardiovascular disease.MethodsUsing a panel study design, 13 participants with coronary artery disease were assessed for markers of systemic inflammation, heart rate variability and repolarization, lipids, blood pressure, and endothelial function. Daily measurements of ozone and particulate matter (PM2.5) were obtained from central monitoring stations. Single (ozone) and two-pollutant (ozone and PM2.5) models were used to assess percent changes in measurements per interquartile ranges of pollutants.ResultsPer interquartile increase in ozone, changes in tissue plasminogen factor (6.6%, 95% confidence intervals (CI) = 0.4, 13.2), plasminogen activator inhibitor-1 (40.5%, 95% CI = 8.7, 81.6), neutrophils (8.7% 95% CI = 1.5, 16.4), monocytes (10.2%, 95% CI = 1.0, 20.1), interleukin-6 (15.9%, 95% CI = 3.6, 29.6), large-artery elasticity index (−19.5%, 95% CI = −34.0, −1.7), and the baseline diameter of the brachial artery (−2.5%, 95% CI = −5.0, 0.1) were observed. These associations were robust in the two-pollutant model.ConclusionsWe observed alterations across several pathways associated with cardiovascular disease in 13 coronary artery disease patients following ozone exposures, independent of PM2.5. The results support the biological plausibility of ozone-induced cardiovascular effects. The effects were found at concentrations below the EPA National Ambient Air Quality Standards for both ozone and PM2.5.

Increasing the Use of Earth Science Data and Models in Air Quality Management

ABSTRACTIn 2010, the U.S. National Aeronautics and Space Administration (NASA) initiated the Air Quality Applied Science Team (AQAST) as a 5-year, $17.5-million award with 19 principal investigators. AQAST aims to increase the use of Earth science products in air quality-related research and to help meet air quality managers’ information needs. We conducted a Web-based survey and a limited number of follow-up interviews to investigate federal, state, tribal, and local air quality managers’ perspectives on usefulness of Earth science data and models, and on the impact AQAST has had. The air quality managers we surveyed identified meeting the National Ambient Air Quality Standards for ozone and particulate matter, emissions from mobile sources, and interstate air pollution transport as top challenges in need of improved information. Most survey respondents viewed inadequate coverage or frequency of satellite observations, data uncertainty, and lack of staff time or resources as barriers to increased use of satellite data by their organizations. Managers who have been involved with AQAST indicated that the program has helped build awareness of NASA Earth science products, and assisted their organizations with retrieval and interpretation of satellite data and with application of global chemistry and climate models. AQAST has also helped build a network between researchers and air quality managers with potential for further collaborations.Implications: NASA’s Air Quality Applied Science Team (AQAST) aims to increase the use of satellite data and global chemistry and climate models for air quality management purposes, by supporting research and tool development projects of interest to both groups. Our survey and interviews of air quality managers indicate they found value in many AQAST projects and particularly appreciated the connections to the research community that the program facilitated. Managers expressed interest in receiving continued support for their organizations’ use of satellite data, including assistance in retrieving and interpreting data from future geostationary platforms meant to provide more frequent coverage for air quality and other applications.

Observing entrainment mixing, photochemical ozone production, and regional methane emissions by aircraft using a simple mixed-layer framework

Abstract. In situ flight data from two distinct campaigns during winter and summer seasons in the San Joaquin Valley (SJV) of California are used to calculate boundary-layer entrainment rates, ozone photochemical production rates, and regional methane emissions. Flights near Fresno, California, in January and February 2013 were conducted in concert with the NASA DISCOVER-AQ project. The second campaign (ArvinO3), consisting of 11 days of flights spanning June through September 2013 and 2014, focused on the southern end of the SJV between Bakersfield and the small town of Arvin, California – a region notorious for frequent violations of ozone air quality standards. Entrainment velocities, the parameterized rates at which free tropospheric air is incorporated into the atmospheric boundary layer (ABL), are estimated from a detailed budget of the inversion base height. During the winter campaign near Fresno, we find an average midday entrainment velocity of 1.5 cm s−1, and a maximum of 2.4 cm s−1. The entrainment velocities derived during the summer months near Bakersfield averaged 3 cm s−1 (ranging from 0.9 to 6.5 cm s−1), consistent with stronger surface heating in the summer months. Using published data on boundary-layer heights we find that entrainment rates across the Central Valley of California have a bimodal annual distribution peaking in spring and fall when the lower tropospheric stability (LTS) is changing most rapidly.Applying the entrainment velocities to a simple mixed-layer model of three other scalars (O3, CH4, and H2O), we solve for ozone photochemical production rates and find wintertime ozone production (2.8 ± 0.7 ppb h−1) to be about one-third as large as in the summer months (8.2 ± 3.1 ppb h−1). Moreover, the summertime ozone production rates observed above Bakersfield–Arvin exhibit an inverse relationship to a proxy for the volatile organic compound (VOC) : NOx ratio (aircraft [CH4] divided by surface [NO2]), consistent with a NOx-limited photochemical environment. A similar budget closure approach is used to derive the regional emissions of methane, yielding 100 (±100) Gg yr−1 for the winter near Fresno and 170 (±125) Gg yr−1 in the summer around Bakersfield. These estimates are 3.6 and 2.4 times larger, respectively, than current state inventories suggest. Finally, by performing a boundary-layer budget for water vapor, surface evapotranspiration rates appear to be consistently ∼ 55 % of the reference values reported by the California Irrigation Management Information System (CIMIS) for nearby weather stations.

Modeled response of ozone to electricity generation emissions in the northeastern United States using three sensitivity techniques

ABSTRACTElectrical generation units (EGUs) are important sources of nitrogen oxides (NOx) that contribute to ozone air pollution. A dynamic management system can anticipate high ozone and dispatch EGU generation on a daily basis to attempt to avoid violations, temporarily scaling back or shutting down EGUs that most influence the high ozone while compensating for that generation elsewhere. Here we investigate the contributions of NOx from individual EGUs to high daily ozone, with the goal of informing the design of a dynamic management system. In particular, we illustrate the use of three sensitivity techniques in air quality models—brute force, decoupled direct method (DDM), and higher-order DDM—to quantify the sensitivity of high ozone to NOx emissions from 80 individual EGUs. We model two episodes with high ozone in the region around Pittsburgh, PA, on August 4 and 13, 2005, showing that the contribution of 80 EGUs to 8-hr daily maximum ozone ranges from 1 to >5 ppb at particular locations. At these locations and on the two high ozone days, shutting down power plants roughly 1.5 days before the 8-hr ozone violation causes greater ozone reductions than 1 full day before; however, the benefits of shutting down roughly 2 days before the high ozone are modest compared with 1.5 days. Using DDM, we find that six EGUs are responsible for >65% of the total EGU ozone contribution at locations of interest; in some locations, a single EGU is responsible for most of the contribution. Considering ozone sensitivities for all 80 EGUs, DDM performs well compared with a brute-force simulation with a small normalized mean bias (–0.20), while this bias is reduced when using the higher-order DDM (–0.10).Implications: Dynamic management of electrical generation has the potential to meet daily ozone air quality standards at low cost. We show that dynamic management can be effective at reducing ozone, as EGU contributions are important and as the number of EGUs that contribute to high ozone in a given location is small (<6). For two high ozone days and seven geographic regions, EGUs would best be shut down or their production scaled back roughly 1.5 days before the forecasted exceedance. Including online sensitivity techniques in an air quality forecasting model can provide timely and useful information on which EGUs would be most beneficial to shut down or scale back temporarily.

The National Ambient Air Quality Standards for Ozone

For the past 45 years, the EPA has set uniform national ambient air quality standards for common pollutants pursuant to the mandate of the Clean Air Act. The pollutant that has been the most difficult to control is ozone. Much of the nation’s population lives in areas that fail to meet the health-based standards for this pollutant. Ozone nonattainment areas include most of California and the Northeast corridor from Northern Virginia to New York, as well as many of the largest metropolitan areas throughout the nation. Over the years, updated ozone standards have become increasingly stringent, which is resulting in a backlash over the cost of compliance. The compliance requirements are particularly challenging for rural areas in the West, where imported pollution and less than ideal meteorological conditions make compliance difficult and costly. Costs have not been used when determining air quality standards, but this may not be the best policy decision. The EPA is ratcheting down the ozone standards and this will add many new nonattainment areas with new responsibilities for controlling air emissions. This can be expected to lead to more confrontation between the regulated states and the EPA.

Source apportionment of emissions from light-duty gasoline vehicles and other sources in the United States for ozone and particulate matter

ABSTRACTFederal Tier 3 motor vehicle emission and fuel sulfur standards have been promulgated in the United States to help attain air quality standards for ozone and PM2.5 (particulate matter with an aerodynamic diameter <2.5 μm). The authors modeled a standard similar to Tier 3 (a hypothetical nationwide implementation of the California Low Emission Vehicle [LEV] III standards) and prior Tier 2 standards for on-road gasoline-fueled light-duty vehicles (gLDVs) to assess incremental air quality benefits in the United States (U.S.) and the relative contributions of gLDVs and other major source categories to ozone and PM2.5 in 2030. Strengthening Tier 2 to a Tier 3-like (LEV III) standard reduces the summertime monthly mean of daily maximum 8-hr average (MDA8) ozone in the eastern U.S. by up to 1.5 ppb (or 2%) and the maximum MDA8 ozone by up to 3.4 ppb (or 3%). Reducing gasoline sulfur content from 30 to 10 ppm is responsible for up to 0.3 ppb of the improvement in the monthly mean ozone and up to 0.8 ppb of the improvement in maximum ozone. Across four major urban areas—Atlanta, Detroit, Philadelphia, and St. Louis—gLDV contributions range from 5% to 9% and 3% to 6% of the summertime mean MDA8 ozone under Tier 2 and Tier 3, respectively, and from 7% to 11% and 3% to 7% of the maximum MDA8 ozone under Tier 2 and Tier 3, respectively. Monthly mean 24-hr PM2.5 decreases by up to 0.5 μg/m3 (or 3%) in the eastern U.S. from Tier 2 to Tier 3, with about 0.1 μg/m3 of the reduction due to the lower gasoline sulfur content. At the four urban areas under the Tier 3 program, gLDV emissions contribute 3.4–5.0% and 1.7–2.4% of the winter and summer mean 24-hr PM2.5, respectively, and 3.8–4.6% and 1.5–2.0% of the mean 24-hr PM2.5 on days with elevated PM2.5 in winter and summer, respectively.Implications: Following U.S. Tier 3 emissions and fuel sulfur standards for gasoline-fueled passenger cars and light trucks, these vehicles are expected to contribute less than 6% of the summertime mean daily maximum 8-hr ozone and less than 7% and 4% of the winter and summer mean 24-hr PM2.5 in the eastern U.S. in 2030. On days with elevated ozone or PM2.5 at four major urban areas, these vehicles contribute less than 7% of ozone and less than 5% of PM2.5, with sources outside North America and U.S. area source emissions constituting some of the main contributors to ozone and PM2.5, respectively.

Inland Concentrations of Cl2 and ClNO2 in Southeast Texas Suggest Chlorine Chemistry Significantly Contributes to Atmospheric Reactivity

Measurements of molecular chlorine (Cl2), nitryl chloride (ClNO2), and dinitrogen pentoxide (N2O5) were taken as part of the DISCOVER-AQ Texas 2013 campaign with a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) using iodide (I-) as a reagent ion. ClNO2 concentrations exceeding 50 ppt were regularly detected with peak concentrations typically occurring between 7:00 a.m. and 10:00 am. Hourly averaged Cl2 concentrations peaked daily between 3:00 p.m. and 4:00 p.m., with a 29-day average of 0.9 ± 0.3 (1σ) ppt. A day-time Cl2 source of up to 35 ppt∙h−1 is required to explain these observations, corresponding to a maximum chlorine radical (Cl•) production rate of 70 ppt∙h−1. Modeling of the Cl2 source suggests that it can enhance daily maximum O3 and RO2• concentrations by 8%–10% and 28%–50%, respectively. Modeling of observed ClNO2 assuming a well-mixed nocturnal boundary layer indicates O3 and RO2• enhancements of up to 2.1% and 38%, respectively, with a maximum impact in the early morning. These enhancements affect the formation of secondary organic aerosol and compliance with air quality standards for ozone and particulate matter.

Ozone and NO&amp;lt;sub&amp;gt;&amp;lt;i&amp;gt;x&amp;lt;/i&amp;gt;&amp;lt;/sub&amp;gt; chemistry in the eastern US: evaluation of CMAQ/CB05 with satellite (OMI) data

Abstract. Regulatory air quality models, such as the Community Multiscale Air Quality model (CMAQ), are used by federal and state agencies to guide policy decisions that determine how to best achieve adherence with National Ambient Air Quality Standards for surface ozone. We use observations of ozone and its important precursor NO2 to test the representation of the photochemistry and emission of ozone precursors within CMAQ. Observations of tropospheric column NO2 from the Ozone Monitoring Instrument (OMI), retrieved by two independent groups, show that the model overestimates urban NO2 and underestimates rural NO2 under all conditions examined for July and August 2011 in the US Northeast. The overestimate of the urban to rural ratio of tropospheric column NO2 for this baseline run of CMAQ (CB05 mechanism, mobile NOx emissions from the National Emissions Inventory; isoprene emissions from MEGAN v2.04) suggests this model may underestimate the importance of interstate transport of NOx. This CMAQ simulation leads to a considerable overestimate of the 2-month average of 8 h daily maximum surface ozone in the US Northeast, as well as an overestimate of 8 h ozone at AQS sites during days when the state of Maryland experienced NAAQS exceedances. We have implemented three changes within CMAQ motivated by OMI NO2 as well as aircraft observations obtained in July 2011 during the NASA DISCOVER-AQ campaign: (a) the modeled lifetime of organic nitrates within CB05 has been reduced by a factor of 10, (b) emissions of NOx from mobile sources has been reduced by a factor of 2, and (c) isoprene emissions have been reduced by using MEGAN v2.10 rather than v2.04. Compared to the baseline simulation, the CMAQ run using all three of these changes leads to considerably better simulation of column NO2 in both urban and rural areas, better agreement with the 2-month average of daily 8 h maximum ozone in the US Northeast, fewer number of false positives of an ozone exceedance throughout the domain, as well as an unbiased simulation of surface ozone at ground-based AQS sites in Maryland that experienced an ozone exceedance during July and August 2007. These modifications to CMAQ may provide a framework for use in studies focused on achieving future adherence to specific air quality standards for surface ozone by reducing emission of NOx from various anthropogenic sectors.

Climate variability modulates western US ozone air quality in spring via deep stratospheric intrusions.

Evidence suggests deep stratospheric intrusions can elevate western US surface ozone to unhealthy levels during spring. These intrusions can be classified as ‘exceptional events', which are not counted towards non-attainment determinations. Understanding the factors driving the year-to-year variability of these intrusions is thus relevant for effective implementation of the US ozone air quality standard. Here we use observations and model simulations to link these events to modes of climate variability. We show more frequent late spring stratospheric intrusions when the polar jet meanders towards the western United States, such as occurs following strong La Niña winters (Niño3.4<−1.0 °C). While El Niño leads to enhancements of upper tropospheric ozone, we find this influence does not reach surface air. Fewer and weaker intrusion events follow in the two springs after the 1991 volcanic eruption of Mt. Pinatubo. The linkage between La Niña and western US stratospheric intrusions can be exploited to provide a few months of lead time during which preparations could be made to deploy targeted measurements aimed at identifying these exceptional events.

Effects of City Specific Data on Health Impact Assessments of Reduced Ozone Concentrations

Health impact assessments of air pollution reductions are nationally performed to assess regulatory policy and public health benefits. The EPA often relies on national endpoints, despite substantial research establishing spatial variability of exposure factors (e.g. concentration-response function and background pollutant concentrations). This project re-examines health impact assessments by utilizing regionally and spatially specific data compared to the nation-wide approach to assess their influence on estimates of avoided health outcomes. A health impact assessment of avoided premature mortality resulting from a stricter hypothetical ozone air quality standard of 70ppb was performed for 44 U.S. cities. Analyses used typical national endpoints, plus combinations of varying city-specific data for three components: 1) concentration-response (C-R) functions, 2) policy relevant background concentrations, 3) and conversion factors to go from 24hr-mean estimates to 8-hr maximum estimates. Analysis was performed with the BenMAP software (version 4.04) Initial results demonstrate that of the city-specific variables, the C-R function substantially drives estimates of avoided mortality. The conversion factor affects a few cities (Los Angeles, Washington DC, Baton Rouge), while the policy relevant ozone background shows little impact on overall estimates with the exception of Las Vegas. Of the 44 cities examined, city-specific conversion factors reduced avoided mortality estimates in 26 cities, while city-specific C-R functions result in equal gains and losses in avoided mortality among locations. A health impact assessment using the national level data estimates 342 avoided annual mortalities for the 44 cities combined, while applying city-specific data estimates 316 avoided mortalities. This study demonstrates the sensitivity of health benefit estimations when incorporating regionally specific data, as opposed to national values.

Assessing exceedance of ozone standards: a space‐time downscaler for fourth highest ozone concentrations

The US Environmental Protection Agency is required to monitor, regulate, and set national ambient air quality standards for ozone. To investigate ozone exposure, the Environmental Protection Agency utilizes monitoring devices along with estimates of gridded ground level ozone concentration produced by a deterministic air quality model, the Community Multiscale Air Quality Model. These two sources of information enable inference regarding spatial exceedance of the National Ambient Air Quality Standard for ozone, which is given in terms of the level of the annual fourth highest ozone concentration.Here, we extend previous downscaling work to propose a spatial fourth highest extreme value downscaling model to assimilate annual fourth highest ozone concentration data at geo‐coded locations with estimates at grid cell level derived from the Community Multiscale Air Quality Model model output. The resulting inference enables us to make probabilistic statements, with associated uncertainty, about the spatial variation in the chance of exceeding the standard. We apply our approach to data in the Eastern USA during years 2001–2008 and compare its predictive performance to that of downscaler models based on Gaussian processes applied to daily data. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Do air quality alerts reduce traffic? An analysis of traffic data from the Salt Lake City metropolitan area, Utah, USA

Air quality alert programs are a form of “soft” or persuasion-based policy that is common in metropolitan areas that do not meet federal air quality standards in the United States. These programs disseminate daily air quality conditions, with ordinal ratings describing the health implications and suggesting reductions in automobile use and other actions that contribute to the poor air quality. Evidence regarding the effectiveness of air quality alert programs on driving is less encouraging than other soft policies to discourage driving, with many studies reporting small or no reductions in traffic. This study examines evidence for the effectiveness of air quality alert systems in reducing traffic over a 10-year period in Salt Lake and Davis counties, Utah, USA, a metropolitan area that often does not meet US federal air quality standards for both ground-level ozone in the summer and PM 2.5 pollution in the winter. We find that while air quality alerts have some effectiveness for reducing traffic in the center city, these small reductions are exceeded by larger increases in traffic near the edge of the metropolitan area. These effects are stronger during the PM 2.5 alert season than during the ozone alert season. These increases can be explained as discretionary trips by individuals escaping poor air quality by driving to the mountains. A policy implication is that soft policies alone may not be effective at reducing driving behavior when the public health implication of the message conflicts with its public responsibility implication.

Evaluation of Anthropogenic Air Emissions from Marine Engines in a Coastal Urban Airshed of Texas

Corpus Christi, Texas, is a growing urban area with a busy port and a petrochemical industrial base that is currently in compliance with the US Environmental Protection Agency’s (EPA) National Ambient Air Quality Standards (NAAQS) for ozone. However, the Texas Commission on Environmental Quality (TCEQ) has classified this urban airshed as a near non-attainment area. A comprehensive annual air emission inventory based on marine engines activity was developed for the years of 2006-2009 for the Port of Corpus Christi, Texas using recent EPA approved methodology. A regional-scale photochemical model Comprehensive Air Modeling system with extensions (CAMx) was used to evaluate the impact of these emissions on the ground level ozone concentrations by zeroing out the emissions and employing Direct Decoupled Method (DDM) for sensitivity analysis to estimate the 8-hour ozone sensitivity coefficients due to NOx and VOC emissions from marine engines. The analysis has shown a localized increase of up to 7.8 ppb in the 8-hour ozone concentration very close to the port premises and a decrease of about 1.73 ppb further downwind. Ozone sensitivity analysis using DDM on the 8-hour ozone concentrations showed a higher sensitivity to NOx emissions. Thus, any NOx related controls of marine engines will benefit local urban and regional ozone levels.

Effects of light duty gasoline vehicle emission standards in the United States on ozone and particulate matter

More stringent motor vehicle emission standards are being considered in the United States to attain national air quality standards for ozone and PM2.5. We modeled past, present and potential future US emission standards for on-road gasoline-fueled light duty vehicles (including both cars and light trucks) (LDVs) to assess incremental air quality benefits in the eastern US in 2022. The modeling results show that large benefits in ozone and PM2.5 (up to 16 ppb (14%) reductions in daily maximum 8-h ozone, up to 10 ppb (11%) reductions in the monthly mean of daily maximum 8-h ozone, up to 4.5 μg m−3 (9%) reductions in maximum 24-h PM2.5 and up to 2.1 μg m−3 (10%) reductions in the monthly mean PM2.5) accrued from the transition from Tier 1 to Tier 2 standards. However, the implementation of additional nationwide LDV controls similar to draft proposed California LEV III regulations would result in very small additional improvements in air quality by 2022 (up to 0.3 ppb (0.3%) reductions in daily maximum 8-h ozone, up to 0.2 ppb (0.2%) reductions in the monthly mean of daily maximum 8-h ozone, up to 0.1 μg m−3 (0.5%) reductions in maximum 24-h PM2.5 and up to 0.1 μg m−3 (0.5%) reductions in the monthly mean PM2.5). The complete elimination of gasoline-fueled LDV emissions in 2022 is predicted to result in improvements in air quality (up to 7 ppb (8%) reductions in daily maximum 8-h ozone, up to 4 ppb (6%) reductions in the monthly mean of daily maximum 8-h ozone, up to 2.8 μg m−3 (7%) reductions in maximum 24-h PM2.5 and up to 1.8 μg m−3 (8%) reductions in the monthly mean PM2.5) from Tier 2 levels, that are generally smaller than the improvements obtained in switching from Tier 1 to Tier 2.

Toward a Political Economy of Cost-Benefit Analysis

This is a substantially revised, refocused, and updated version of an earlier draft paper, exploring the significant role Cost-Benefit Analysis (CBA) plays in facilitating or impeding legislative and regulatory policy decisions. The paper centers around three case studies of CBAs EPA prepared for: (1) Clinton Administration changes to Clean Air Act air quality standards for ozone and particulate matter; (2) President Obama's recent decision to suspend EPA's reconsideration of the Bush Administration's air quality standard for ozone; and (3) the George W. Bush Administration's Clear Skies legislative initiative. The first two case studies demonstrate, between them, how well-constructed CBAs can facilitate social welfare-enhancing and impede welfare-reducing rules, even in cases where explicit consideration of costs is legally prohibited. The third case study tells a more complex story of how CBAs can be manipulated either to promote welfare-reducing regulations or impede welfare-enhancing regulations. When that happens, however, the virtuous transparency of CBAs renders those efforts liable to discovery and disclosure, as in the case of the Bush Administration's failed Clear Skies initiative. The paper concludes with an assessment of implications of the case studies for our understanding of the role of CBA in political (both legislative and regulatory) processes, and with a call for more qualitative and quantitative empirical research on the use and abuse of CBA as a political tool.