Air Quality Planning Research Articles

Analyzing the efficiency of short-term air quality plans in European cities, using the CHIMERE air quality model

Regional and local authorities have the obligation to design air quality plans and assess their impacts when concentration levels exceed the limit values. Because these limit values cover both short- (day) and long-term (year) effects, air quality plans also follow these two formats. In this work, we propose a methodology to analyze modeled air quality forecast results, looking at emission reduction for different sectors (residential, transport, agriculture, etc.) with the aim of supporting policy makers in assessing the impact of short-term action plans. Regarding PM10, results highlight the diversity of responses across European cities, in terms of magnitude and type that raises the necessity of designing area-specific air quality plans. Action plans extended from 1 to 3 days (i.e., emissions reductions applied for 24 and 72 h, respectively) point to the added value of trans-city coordinated actions. The largest benefits are seen in central Europe (Vienna, Prague) while major cities (e.g., Paris) already solve a large part of the problem on their own. Eastern Europe would particularly benefit from plans based on emission reduction in the residential sectors; while in northern cities, agriculture seems to be the key sector on which to focus attention. Transport is playing a key role in most cities whereas the impact of industry is limited to a few cities in south-eastern Europe. For NO2, short-term action plans focusing on traffic emission reductions are efficient in all cities. This is due to the local character of this type of pollution. It is important, however, to stress that these results remain dependent on the selected months available for this study.

A cost-efficiency and health benefit approach to improve urban air quality

When ambient air quality standards established in the EU Directive 2008/50/EC are exceeded, Member States are obliged to develop and implement Air Quality Plans (AQP) to improve air quality and health. Notwithstanding the achievements in emission reductions and air quality improvement, additional efforts need to be undertaken to improve air quality in a sustainable way – i.e. through a cost-efficiency approach. This work was developed in the scope of the recently concluded MAPLIA project “Moving from Air Pollution to Local Integrated Assessment”, and focuses on the definition and assessment of emission abatement measures and their associated costs, air quality and health impacts and benefits by means of air quality modelling tools, health impact functions and cost-efficiency analysis. The MAPLIA system was applied to the Grande Porto urban area (Portugal), addressing PM10 and NOx as the most important pollutants in the region. Four different measures to reduce PM10 and NOx emissions were defined and characterized in terms of emissions and implementation costs, and combined into 15 emission scenarios, simulated by the TAPM air quality modelling tool. Air pollutant concentration fields were then used to estimate health benefits in terms of avoided costs (external costs), using dose-response health impact functions. Results revealed that, among the 15 scenarios analysed, the scenario including all 4 measures lead to a total net benefit of 0.3M€·y−1. The largest net benefit is obtained for the scenario considering the conversion of 50% of open fire places into heat recovery wood stoves. Although the implementation costs of this measure are high, the benefits outweigh the costs. Research outcomes confirm that the MAPLIA system is useful for policy decision support on air quality improvement strategies, and could be applied to other urban areas where AQP need to be implemented and monitored.

Air quality from a social perspective in four European metropolitan areas: Research hypothesis and evidence from the SEFIRA project

This paper analyses social constraints influencing air quality governance in four European Union (EU) countries. The comparative analysis carried out here is the outcome of the EU FP7 SEFIRA project. Starting from study of implemented measures the paper marks out the structure of double-delegation in policy-making for air quality governance; that is to say the delegation from the EU to national governments who further delegate to regional and local authorities the burden to put in place concrete measures. Therefore, our analysis has followed a multi-level approach considering all the territorial level down to the urban scale. In doing so, we found out commonalities in the strategies which have been followed by policy-makers. The comparison has been made possible through the analysis of operationalised categories such as Domain, Objectives and Modalities on air quality plans. The analysis went further: through interviews with selected key stakeholder the social constraints which may limit the choices made by institutions have been investigated. The -lack of- success in attaining EU requirements for the air quality cannot be considered only as the outcome of the −lack of- awareness of which may be the best practices or choices, rather as the result of complex entanglements of social forces. Indeed, one of the main outcomes of this explorative investigation has been the breakdown of such complexity into its social component in a comparative study. The paper finally points out the need to promote an integrated approach for air quality policy as a strategy for the design of new measures for the future.

A decision framework for Integrated Assessment Modelling of air quality at regional and local scale

Decision making in the field of air quality and greenhouses gases reductions can nowadays be supported by a clear overall framework and by computer tools that integrate the most relevant aspects of the problem. This approach is particularly important at local scale since new general rules on emission abatement at European level can only marginally modify the most critical hotspots and may be very costly. This paper adapts the general Drivers, Pressures, State, Impacts, Responses (DPSIR) scheme proposed by the European Environment Agency to the specific case of local air quality policies and shows how the most recent scientific developments in impact evaluation and social acceptance can be integrated. The proposed decision framework represents a general methodology to design Integrated Assessment Modelling (IAM) systems aimed at the implementation of effective Air Quality Plans (AQP). An extensive survey across European countries shows the current degree of adoption of these approaches.

Lazy Learning based surrogate models for air quality planning

Air pollution in atmosphere derives from complex non-linear relationships, involving anthropogenic and biogenic precursor emissions. Due to this complexity, Decision Support Systems (DSSs) are important tools to help Environmental Authorities to control/improve air quality, reducing human and ecosystems pollution impacts. DSSs implementing cost-effective or multi-objective methodologies require fast air quality models, able to properly describe the relations between emissions and air quality indexes. These, namely surrogate models (SM), are identified processing deterministic model simulation data. In this work, the Lazy Learning technique has been applied to reproduce the relations linking precursor emissions and pollutant concentrations. Since computational time has to be minimized without losing precision and accuracy, tests aimed at reducing the amount of input data have been performed on a case study over Lombardia Region in Northern Italy.

Applying integrated assessment methodologies to air quality plans: Two European cases

Air pollution Integrated Assessment Models (IAM) can be used for determining how emissions should be reduced to improve air quality and to protect human health in a cost-efficient way. The application of IAM is also useful to spread information to the general public and to explain the effectiveness of proposed Air Quality Plans. In this paper, the application of the RIAT+ system to determine suitable abatement measures to improve the air quality at a regional/local level is presented for two European cases: the Brussels Capital Region (Belgium) and the Porto Urban Area (Portugal). Both regions are affected with PM10 or NO2 concentrations that exceed the limit values specified by the European Union legislation. To properly assess air quality abatement measures a surrogate model was used, allowing the implementation of an efficient optimization procedure. This model is derived in both cases through a set of simulations performed using a Chemistry Transport Model fed with different emission reduction scenarios. In addition, internal costs (due to the implementation of emission reduction measures) and external costs (due to population exposure to air pollutant concentrations) of policy options were considered. The application of this integrated assessment modelling system in scenario (Brussels case) and optimization (Porto) modes contributes to identifying some advantages and limitations of these two approaches and also provides some guidance when urban air quality has to be assessed.

EFFECT OF THE APULIA AIR QUALITY PLAN ON PM10 AND BENZO (A) PYRENE EXCEEDANCES

During the last years, several exceedances of PM10 and benzo(a)pyrene limit values exceedances were recorded in Taranto, a city in southern Italy included in so-called areas at high risk of environmental crisis because of the presence of a heavy industrial district including the largest steel factory in Europe. A study of these critical pollution events showed a close correlation with the wind coming from the industrial site to the adjacent urban area. During 2011, at monitoring sites closes to the industrial area, at least the 65% of PM10 exceedances were related to wind day conditions (characterized by at least 3 consecutive hours of wind coming from 270-360±2deg with an associated speed higher than 7 m/s). For this reason, in 2012 an integrated environmental permit and a regional air quality plan were enacted to reduce pollutant emissions from industrial plants. A study of PM10 levels registered during windy days was performed during critical episodes of pollution highlighting that the difference between windy days and no windy days’ concentrations reduces from 2012 to 2014 in industrial site. False negative events (verified ex-post by observed meteorological data) not identified by the forecast model - did not show a significant influence on PM concentration: PM10 values were comparable and sometimes lower than windy days levels. It is reasonable that the new scenario with a relevant reduction emissions form Ilva plant reduced the pollutants contribution from industrial area, contributing to PM10 levels decrease, also in false negative events.

Overview of current regional and local scale air quality modelling practices: Assessment and planning tools in the EU

The 2008 European Air Quality Directive (AQD) (2008/50/EC) encourages the use of models in combination with monitoring in a range of applications. It also requires Member States to design appropriate air quality plans for zones where the air quality does not comply with the AQD limit values. In order to cope with these various elements, a wide range of different modeling methods have been developed and applied by EU Member States in the last decade to assess the effects of local and regional emission abatement policy options on air quality and human health. However, an overall review of the methodologies that are used in different countries to compile local and regional air quality plans has not been performed so far. Such a review has been the objective of the APPRAISAL EU FP7 project with the main goal to identify methodologies and their limitations and to propose possible key areas to be addressed by research and innovation on the basis of this review. To fulfill these objectives, a structured online database of methodologies has been developed in collaboration with experts involved in the design of air quality plans (AQP). The current work relies on the APPRAISAL database which currently totals 59 contributions from 13 Member States. In this paper we summarize the outcome of the APPRAISAL project with respect to the review of current Integrated Assessment Modeling practices.

AIRUSE-LIFE+: a harmonized PM speciation and source apportionment in five southern European cities

Abstract. The AIRUSE-LIFE+ project aims at characterizing similarities and heterogeneities in particulate matter (PM) sources and contributions in urban areas from southern Europe. Once the main PMx sources are identified, AIRUSE aims at developing and testing the efficiency of specific and non-specific measures to improve urban air quality. This article reports the results of the source apportionment of PM10 and PM2.5 conducted at three urban background sites (Barcelona, Florence and Milan, BCN-UB, FI-UB and MLN-UB), one suburban background site (Athens, ATH-SUB) and one traffic site (Porto, POR-TR). After collecting 1047 PM10 and 1116 PM2.5 24 h samples during 12 months (from January 2013 on) simultaneously at the five cities, these were analysed for the contents of OC, EC, anions, cations, major and trace elements and levoglucosan. The USEPA PMF5 receptor model was applied to these data sets in a harmonized way for each city. The sum of vehicle exhaust (VEX) and non-exhaust (NEX) contributes between 3.9 and 10.8 µg m−3 (16–32 %) to PM10 and 2.3 and 9.4 µg m−3 (15–36 %) to PM2.5, although a fraction of secondary nitrate is also traffic-related but could not be estimated. Important contributions arise from secondary particles (nitrate, sulfate and organics) in PM2.5 (37–82 %) but also in PM10 (40–71 %), mostly at background sites, revealing the importance of abating gaseous precursors in designing air quality plans. Biomass burning (BB) contributions vary widely, from 14–24 % of PM10 in POR-TR, MLN-UB and FI-UB, 7 % in ATH-SUB, to < 2 % in BCN-UB. In PM2.5, BB is the second most important source in MLN-UB (21 %) and in POR-TR (18 %), the third one in FI-UB (21 %) and ATH-SUB (11 %), but is again negligible (< 2 %) in BCN-UB. This large variability among cities is mostly due to the degree of penetration of biomass for residential heating. In Barcelona natural gas is very well supplied across the city and is used as fuel in 96 % of homes, while in other cities, PM levels increase on an annual basis by 1–9 µg m−3 due to biomass burning influence. Other significant sources are the following. – Local dust, 7–12 % of PM10 at SUB and UB sites and 19 % at the TR site, revealing a contribution from road dust resuspension. In PM2.5 percentages decrease to 2–7 % at SUB-UB sites and 15 % at the TR site. – Industry, mainly metallurgy, contributing 4–11 % of PM10 (5–12 % in PM2.5), but only at BCN-UB, POR-TR and MLN-UB. No clear impact of industrial emissions was found in FI-UB and ATH-SUB. – Natural contributions from sea salt (13 % of PM10 in POR-TR, but only 2–7 % in the other cities) and Saharan dust (14 % in ATH-SUB, but less than 4 % in the other cities). During high pollution days, the largest sources (i.e. excluding secondary aerosol factors) of PM10 and PM2.5 are VEX + NEX in BCN-UB (27–22 %) and POR-TR (31–33 %), BB in FI-UB (30–33 %) and MLN-UB (35–26 %) and Saharan dust in ATH-SUB (52–45 %). During those days, there are also quite important industrial contributions in BCN-UB (17–18 %) and local dust in POR-TR (28–20 %).

Using a Coupled Air Quality Modeling System for the Development of an Air Quality Plan in Madrid (Spain): Source Apportionment and Analysis Evaluation of Mitigation Measures

In this contribution, we use a coupled air quality modelling system (AQM) as a tool to design and develop an air quality plan in Madrid. AQM has allowed us to obtain a preliminary evaluation of the effect of mitigation measures over regional and local air quality levels. To achieve these goals, we have prepared a sophisticated AQM, coupling the meteorological model WRF, the emission model AEMM, and the photochemical model CMAQ. AQM was evaluated using the whole modelling year 2010 working with high horizontal resolution, 3 km for the region of Madrid and 1km for urban metropolitan area of Madrid. Two different analyses have been realized: a source apportionment exercise following a zero-out methodology to obtain the contribution to the air quality levels of the different emission sector; and an evaluation of the main mitigation measures considered in the air quality plan using sensitivity analysis. The air quality plan was focused on the improvement of NO2 levels and AQM analyzed the effect of the mitigation measures during ten episodes of 2011 where NO2 or O3 levels were the highest of the year; so we analyzed the effect of the mitigation plan in worst conditions. Results provided by the AQM system show that it accomplishes the European Directive modelling uncertainty requirements and the mean absolute gross error for 1-h maximum daily NO2 is 31% over locations with higher levels of this atmospheric pollutant; the road traffic is the main contributor to the air quality levels providing a 81% for NO2, 67% for CO and 46% for PM10; measures defined in the plan achieve to reduce up to 11 μgm-3 NO2 levels offering highest reductions over urban areas with traffic influence.

Estimating Project-Level Vehicle Emissions with Vissim and MOVES-Matrix

Estimating transportation network emissions requires multiplying estimates of on-road vehicle activity (by source type and operating mode) by applicable emission rates for the observed source type and operating conditions. Coupling microsimulation model runs with emissions modeling can make fast assessments possible in transportation air quality planning. This research developed a tool with automated linkage between the Vissim microsimulation model and the Motor Vehicle Emission Simulator (MOVES) model. To link the two models, the research team used MOVES-Matrix, which was prepared by iteratively running MOVES across all possible iterations of vehicle source type, fuel, environmental and operating conditions, and other parameters (hundreds of millions of model runs) to create a multidimensional emission rate lookup matrix. A Vissim simulation of the major arterial roads and freeways at I-85 and Jimmy Carter Boulevard in Gwinnett County, Georgia, provided the case study for this MOVES-matrix application. The researchers present predicted emissions and the results of a sensitivity analysis to identify the potential impacts of various internal Vissim modeling parameters (such as minimum headway, maximum deceleration rate for cooperative braking, and emergency stop distance) on a case study’s emissions outputs. The sensitivity analysis found that internal Vissim parameters impacted emissions and that proper care should be taken in using Vissim for emissions analysis at the corridor and link level. The case study demonstrates that Vissim coupled with MOVES-Matrix can be an effective tool for emissions analysis.

Local source identification of trace metals in urban/industrial mixed land-use areas with daily PM10 limit value exceedances

This study presents the analysis of the concentration levels, inter-site variation and source identification of trace metals at three urban/industrial mixed land-use sites of the Cantabria region (northern Spain), where local air quality plans were recently approved because the number of exceedances of the daily PM10 limit value according to the Directive 2008/50/EC had been relatively high in the last decade (more than 35 instances per year). PM10 samples were collected for over three years at the Torrelavega (TORR) and Los Corrales (CORR) sites and for over two years at the Camargo (GUAR) site and analysed for the presence of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), titanium (Ti), vanadium (V), molybdenum (Mo), manganese (Mn), iron (Fe), antimony (Sb) and zinc (Zn). Analysis of enrichment factors revealed an anthropogenic origin of most of the studied elements; Zn, Cd, Mo, Pb and Cu were the most enriched elements at the three sites, with Fe and V as the least enriched elements. Positive Matrix Factorisation (PMF) and pollutant roses (Cu at TORR, Zn at CORR and Mn at GUAR) were used to identify the local sources of the studied metals. Analysis of PMF results revealed the main sources of trace metals at each site as road traffic at the TORR site, iron foundry and casting industry at the CORR site and a ferro-manganese alloy industry at the GUAR site. Other sources were also identified at these sites, but with much lower contributions, such as minor industrial sources, combustion and traffic mixed with the previous sources.

Evaluating strategies to reduce urban air pollution

Abstract During the last years, specific air quality problems have been detected in the urban area of Porto (Portugal). Both PM10 and NO 2 limit values have been surpassed in several air quality monitoring stations and, following the European legislation requirements, Air Quality Plans were designed and implemented to reduce those levels. In this sense, measures to decrease PM10 and NO 2 emissions have been selected, these mainly related to the traffic sector, but also regarding the industrial and residential combustion sectors. The main objective of this study is to investigate the efficiency of these reduction measures with regard to the improvement of PM10 and NO 2 concentration levels over the Porto urban region using a numerical modelling tool – The Air Pollution Model (TAPM). TAPM was applied over the study region, for a simulation domain of 80 × 80 km 2 with a spatial resolution of 1 × 1 km 2 . The entire year of 2012 was simulated and set as the base year for the analysis of the impacts of the selected measures. Taking into account the main activity sectors, four main scenarios have been defined and simulated, with focus on: (1) hybrid cars; (2) a Low Emission Zone (LEZ); (3) fireplaces and (4) industry. The modelling results indicate that measures to reduce PM10 should be focused on residential combustion (fireplaces) and industrial activity and for NO 2 the strategy should be based on the traffic sector. The implementation of all the defined scenarios will allow a total maximum reduction of 4.5% on the levels of both pollutants.

Air quality plan for ozone: an urgent need for North Portugal

Each summer period, ozone concentrations surpass the legislation limits in the north of Portugal, more precisely at the Douro Norte monitoring station. To solve/mitigate this air pollution problem, and respond to the EU requirements, air quality plans were studied and designed. An air quality numerical modelling system was applied, with a source apportionment technique (to the most relevant ozone episodes) to identify the major source regions and the main activity sectors responsible for the ozone values at this site. Modelling results pointed out that the background values contribute with more than 50 % to the ozone concentration measured, followed by transport and residential sectors—the main anthropogenic activities. More regional and transboundary strategies are needed to reduce the background concentrations, besides local actions on road transport and residential combustion at urban regions (e.g., the Porto area).

Enforcing EU Environmental Law against Member States: Air Pollution, National Courts and the Rule of Law

Case C-404/13, The Queen, on the application of Client Earth v Secretary of State for the Environment, Food and Rural Affairs EU:C:2014:2382, OJ C – 26 of 26.1.2015, p. 6.When a Member State finds that the limit values cannot be respected before the deadline fixed by the Air Quality Directive and wishes to postpone that deadline for a maximum of five years, that Member State is required to make an application for the postponement of the deadline by drawing up an air quality plan demonstrating how those limits will be met before the new deadline (official headnote).

A100 Key factors influencing air quality in rail subway systems

Abstract Background Air quality plans incentivise the use of public transport to abate atmospheric emissions from private road vehicles in cities. In this context rail subway systems are especially desirable as they are based on electric trains, are energetically/environmentally efficient, and help relieve surface traffic congestion. However, a number of studies have revealed poor air quality underground, especially concerning levels of Particulate Matter. Interestingly, some subway systems appear to be worse than others in terms of particle loading, and it is clearly necessary to identify the key factors involved. Methods Ambient subway aerosol particles present in trains and on platforms in the Barcelona metro system have been (and are being) intensively monitored, sampled and physico-chemically characterised, and different types of stations compared. Air monitoring equipment includes high volume samplers for chemical analysis of particles below 2.5 μm, a light-scattering laser photometer for particle concentrations in 3 sizes, and an indoor air quality meter for carbon oxides. Results Outdoor concentrations of traffic particles and gases in Barcelona city do not significantly influence subway air quality, with most particles being ferruginous and sourced underground. Air quality is better inside trains than on platforms, although passenger density clearly affects carbon dioxide levels in both. Stations with cleanest particle concentrations are those fitted with new platform screen door systems, whereas the poorest air quality is associated with older-style narrow single track-tunnel-platform designs. Particle concentration varies along the platform, being influenced by the number and position of passenger exit tunnels, the train frequency and travel direction. Particle composition and morphologies are similar in all stations, indicating a common mechanism of formation, and they are physically and chemically distinctive from particles breathed in outdoor urban air. The iron-rich particles are mostly nanometric in size and derive from mechanical processes of sliding and wear at the brake-wheel and wheel-rail interface, with minor contributions from high temperature processes such as sparking. Conclusions Air quality in the subway environment is an issue of concern due to the high particle concentrations that can be registered, especially on platforms. The variables influencing these concentrations include type and intensity of ventilation, station design, number and location of accesses to platforms and number of trains and passengers. The detailed study of these parameters in a large number of stations within the ongoing research projects METRO and IMPROVE LIFE is enabling us to develop protocols aimed at producing discernible improvements to rail subway air quality.

Current air quality plans in Europe designed to support air quality management policies

The intensification of the human activity in urban areas as a result of the increasing population has contributed to the air pollution worsening in cities. To reverse this trend, the European Commission established a legal framework to improve the air quality. Thereby the Member States need to develop air quality plans (AQP) for zones and agglomerations where air quality limit values are exceeded, in order to implement pollution control strategies and meet the legal requirements. Understanding the reasons for the levels of air quality non–compliance as well as evaluating available and commonly used tools to predict the air quality and their effects, is crucial for the decision–making process on air quality management policies. Based on a compilation of regional and local AQP, a review of assessment capabilities and used modeling tools to evaluate the effects of emission abatement measures on the air quality and health was performed. In most cases, models are applied to estimate emissions and to assess the resulting air quality from both reference and emission abatement scenarios. Air quality’s impacts on the health and environment are rarely quantified. Regarding the air quality assessment, beyond the modeling, monitored data for validation of simulations are also used. Some studies, however, do not include the use of air quality models, considering the monitoring network as spatially representative of the study domain (e.g. Lisbon Region, Riga, Malta). In order to overcome methodological limitations for quantifying the impacts of emission abatement measures, economic evaluation techniques or even Integrated Assessment Methodologies (IAM) have been developed. IAM, already applied in some AQP or case studies, namely for Antwerp and London, are used for assessing how reductions in emissions contribute to improve air quality, reduce exposure and protect human health.

How emissions, climate, and land use change will impact mid-century air quality over the United States: a focus on effects at national parks

Abstract. We use a global coupled chemistry–climate–land model (CESM) to assess the integrated effect of climate, emissions and land use changes on annual surface O3 and PM2.5 in the United States with a focus on national parks (NPs) and wilderness areas, using the RCP4.5 and RCP8.5 projections. We show that, when stringent domestic emission controls are applied, air quality is predicted to improve across the US, except surface O3 over the western and central US under RCP8.5 conditions, where rising background ozone counteracts domestic emission reductions. Under the RCP4.5 scenario, surface O3 is substantially reduced (about 5 ppb), with daily maximum 8 h averages below the primary US Environmental Protection Agency (EPA) National Ambient Air Quality Standards (NAAQS) of 75 ppb (and even 65 ppb) in all the NPs. PM2.5 is significantly reduced in both scenarios (4 μg m−3; ~50%), with levels below the annual US EPA NAAQS of 12 μg m−3 across all the NPs; visibility is also improved (10–15 dv; >75 km in visibility range), although some western US parks with Class I status (40–74 % of total sites in the US) are still above the 2050 planned target level to reach the goal of natural visibility conditions by 2064. We estimate that climate-driven increases in fire activity may dominate summertime PM2.5 over the western US, potentially offsetting the large PM2.5 reductions from domestic emission controls, and keeping visibility at present-day levels in many parks. Our study indicates that anthropogenic emission patterns will be important for air quality in 2050. However, climate and land use changes alone may lead to a substantial increase in surface O3 (2–3 ppb) with important consequences for O3 air quality and ecosystem degradation at the US NPs. Our study illustrates the need to consider the effects of changes in climate, vegetation, and fires in future air quality management and planning and emission policy making.

Regional ozone impacts of increased natural gas use in the Texas power sector and development in the Eagle Ford shale.

The combined emissions and air quality impacts of electricity generation in the Texas grid and natural gas production in the Eagle Ford shale were estimated at various natural gas price points for the power sector. The increased use of natural gas in the power sector, in place of coal-fired power generation, drove reductions in average daily maximum 8 h ozone concentration of 0.6-1.3 ppb in northeastern Texas for a high ozone episode used in air quality planning. The associated increase in Eagle Ford upstream oil and gas production nitrogen oxide (NOx) emissions caused an estimated local increase, in south Texas, of 0.3-0.7 ppb in the same ozone metric. In addition, the potential ozone impacts of Eagle Ford emissions on nearby urban areas were estimated. On the basis of evidence from this work and a previous study on the Barnett shale, the combined ozone impact of increased natural gas development and use in the power sector is likely to vary regionally and must be analyzed on a case by case basis.

Derivation of exemption formulas for air quality regulatory applications

The regulatory agencies and the industries have the responsibility for assessing the environmental impact from the release of air pollutants, and for protecting environment and public health. The simple exemption formula is often used as a criterion for the purpose of screening air pollutants. That is, the exemption formula is used for air quality review and to determine whether a facility applying for and described in a new, modified, or revised air quality plan is exempted from further air quality review. The Bureau of Ocean Energy Management’s (BOEM) air quality regulations are used to regulate air emissions and air pollutants released from the oil and gas facilities in the Gulf of Mexico. If a facility is not exempt after completing the air quality review, a refined air quality modeling will be required to regulate the air pollutants. However, at present, the scientific basis for BOEM’s exemption formula is not available to the author. Therefore, the purpose of this paper is to provide the theoretical framework and justification for the use of BOEM’s exemption formula. In this paper, several exemption formulas have been derived from the Gaussian and non-Gaussian dispersion models; the Gaussian dispersion model is a special case of non-Gaussian dispersion model. The dispersion parameters obtained from the tracer experiments in the Gulf of Mexico are used in the dispersion models. In this paper, the dispersion parameters used in the dispersion models are also derived from the Monin-Obukhov similarity theory. In particular, it has been shown that the total amount of emissions from the facility for each air pollutant calculated using BOEM’s exemption formula is conservative.Implications: The operation of offshore oil and gas facilities under BOEM’s jurisdiction is required to comply with the BOEM’s regulations. BOEM’s air quality regulations are used to regulate air emissions and air pollutants released from the oil and gas facilities in the Gulf of Mexico. The exemption formulas have been used by BOEM and other regulatory agencies as a screening tool to regulate air emissions emitted from the oil and gas and other industries. Because of the BOEM’s regulatory responsibility, it is important to establish the scientific basis and provide the justification for the exemption formulas. The methodology developed here could also be adopted and used by other regulatory agencies.