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City clusters play an important role in air pollutant and greenhouse gas (GHG) emissions reduction in China, primarily due to their high fossil energy consumption levels. The “2 + 26” Cities, i.e., Beijing, Tianjin and 26 other perfectures in northern China, has experienced serious air pollution in recent years. We employ the Greenhouse Gas and Air Pollution Interactions and Synergies model adapted to the “2 + 26” Cities (GAINS-JJJ) to evaluate the impacts of structural adjustments in four major sectors, industry, energy, transport and land use, under the Three-Year Action Plan for Blue Skies (Three-Year Action Plan) on the emissions of both the major air pollutants and CO2 in the “2 + 26” Cities. The results indicate that the Three-Year Action Plan applied in the “2 + 26” Cities reduces the total emissions of primary fine particulate matter with an aerodynamic diameter of ≤ 2.5 μm (PM2.5), SO2, NOx, NH3 and CO2 by 17%, 25%, 21%, 3% and 1%, respectively, from 2017 to 2020. The emission reduction potentials vary widely across the 28 prefectures, which may be attributed to the differences in energy structure, industrial composition, and policy enforcement rate. Among the four sectors, adjustment of industrial structure attains the highest co-benefits of CO2 reduction and air pollution control due to its high CO2 reduction potential, while structural adjustments in energy and transport attain much lower co-benefits, despite their relatively high air pollutant emissions reductions, primarily resulting from an increase in the coal-electric load and associated carbon emissions caused by electric reform policies.

Air pollution is linked with many of the United Nations Sustainable Development Goals. Strategies aiming at the improved air quality interact directly with climate mitigation targets, access to clean energy services, waste management, and other aspects of socio-economic development. Continuation of current policies in the key emitting sectors implies that a number of sustainability goals will likely not be met within the next two decades: emissions of air pollutants would cause 40% more premature deaths from outdoor air pollution than today, carbon emissions would rise globally by 0.4% per year, while nearly two billion people would not have access to clean cooking. This paper examines integrated policies to put the world on track towards three interlinked goals of achieving universal energy access, limiting climate change and reducing air pollution. Scenario analysis suggests that these goals can be attained simultaneously with substantial benefits. By 2040, emissions of main pollutants are projected to drop by 60–80% relative to today, and associated health impacts are quantified at two million avoided deaths from ambient and household air pollution combined. In comparison to costs needed for the decarbonization of global economy, additional investments in air pollution control and access to clean fuels are very modest against major societal gains. However, holistic and systemic policy assessment is required to avoid potential trade-offs.

Urbanization, population and economic growth in Indian megacities like Delhi have resulted in an increase in energy and transportation demand leading to severe air pollution and related health impacts, as well as to the rapid growth in the greenhouse gas emissions. In this study, an integrated assessment of air quality and climate policies for Indian cities – with a particular focus on National Capital Territory of Delhi, has been carried out. We have developed emission inventory of air pollutants and greenhouse gases for the base year (2010) and evaluated the impact of current policies on emission projections by 2030 in the business-as-usual scenario. Emissions of coarse and fine particulate matter are projected to be 51% and 15% higher in 2030 as compared to present. As the current legislations do not indicate progress towards the achievement of the Indian National Ambient Air Quality Standards in Delhi, we explored the effectiveness of additional emission control strategies with either advanced end-of-pipe emission controls or low carbon policies. Relative to the baseline scenario, the set of alternative policy strategies would reduce emissions rapidly in 2030. The results revealed that air quality policies under various scenarios could also have co-benefits of reducing carbon emissions. At the same time, the results suggest that low carbon policies would be more efficient to cut emissions as compared to advanced end-of-pipe emission control policies. However, their implementation could be limited by the availability of clean fuels. In the climate policy scenario, carbon emission in 2030 is estimated to decrease by 19% relative to baseline. Additional controls combined with low carbon policies like controlling non-industrial emissions create an opportunity to further enhance the scope for co-benefits and to attain the air quality standards in Delhi.

Bottom-up emission inventories provide primary understanding of sources of air pollution and essential input of chemical transport models. Focusing on SO2 and NOx, we conducted a comprehensive evaluation of two widely used anthropogenic emission inventories over China, ECLIPSE and MIX, to explore the potential sources of uncertainties and find clues to improve emission inventories. We first compared the activity rates and emission factors used in two inventories and investigated the reasons of differences and the impacts on emission estimates. We found that SO2 emission estimates are consistent between two inventories (with 1 % differences), while NOx emissions in ECLIPSE's estimates are 16 % lower than those of MIX. The FGD (flue-gas desulfurization) device penetration rate and removal efficiency, LNB (low-NOx burner) application rate and abatement efficiency in power plants, emission factors of industrial boilers and various vehicle types, and vehicle fleet need further verification. Diesel consumptions are quite uncertain in current inventories. Discrepancies at the sectorial and provincial levels are much higher than those of the national total. We then examined the impacts of different inventories on model performance by using the nested GEOS-Chem model. We finally derived top-down emissions by using the retrieved columns from the Ozone Monitoring Instrument (OMI) compared with the bottom-up estimates. High correlations were observed for SO2 between model results and OMI columns. For NOx, negative biases in bottom-up gridded emission inventories (−21 % for MIX, −39 % for ECLIPSE) were found compared to the satellite-based emissions. The emission trends from 2005 to 2010 estimated by two inventories were both consistent with satellite observations. The inventories appear to be fit for evaluation of the policies at an aggregated or national level; more work is needed in specific areas in order to improve the accuracy and robustness of outcomes at finer spatial and also technological levels. To our knowledge, this is the first work in which source comparisons detailed to technology-level parameters are made along with the remote sensing retrievals and chemical transport modeling. Through the comparison between bottom-up emission inventories and evaluation with top-down information, we identified potential directions for further improvement in inventory development.

Based on a McFadden-type conditional logit (CL) discrete choice model, this paper estimates the most economic subsidy level (MESL) for room air conditioners (RACs) in China that minimizes the net cost of subsidy per unit of electricity saved. The analysis reveals that, given the current price and efficiency spectrum of RACs in the Chinese market as well as the electricity price and cooling demand of Chinese households, the MESL for RACs in China should be around 60%, which is much higher than the current subsidy level of 5–15%. A sensitivity analysis suggests that the high MESL (60%) is mainly a consequence of relatively low electricity price and household cooling demand in the country. If China's household cooling demand increases further and its electricity price were to rise to a higher level, the MESL for RACs could possibly drop to about 5–15%. As household cooling demand varies among Chinese cities in different climatic zones and at different levels of economic development, the RAC subsidy incentives should be region-specific. With necessary modifications, the method for analysis proposed in this paper can also be applied to other household appliances to prioritize the types of appliances requiring subsidies.

This paper presents a comprehensive assessment of historical (1990–2010) global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC). The estimates were developed with the integrated assessment model GAINS, where source- and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping), presented for 25 global regions, and allocated to 0.5° × 0.5° longitude–latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30 % in 1990 to well below 15 % in 2010, while Asia's contribution grew from just over 50 % to nearly two-thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60 % of the global anthropogenic total, and residential combustion was the most important sector, contributing about 60 % for BC and OC, 45 % for PM2. 5, and less than 40 % for PM10, where large combustion sources and industrial processes are equally important. Global anthropogenic emissions of BC were estimated at about 6.6 and 7.2 Tg in 2000 and 2010, respectively, and represent about 15 % of PM2. 5 but for some sources reach nearly 50 %, i.e. for the transport sector. Our global BC numbers are higher than previously published owing primarily to the inclusion of new sources. This PM estimate fills the gap in emission data and emission source characterization required in air quality and climate modelling studies and health impact assessments at a regional and global level, as it includes both carbonaceous and non-carbonaceous constituents of primary particulate matter emissions. The developed emission dataset has been used in several regional and global atmospheric transport and climate model simulations within the ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants) project and beyond, serves better parameterization of the global integrated assessment models with respect to representation of black carbon and organic carbon emissions, and built a basis for recently published global particulate number estimates.

Megacities in Asia rank high in air pollution at the global scale. In many cities, ambient concentrations of fine particulate matter (PM2.5) have been exceeding both the WHO interim targets as well as respective national air quality standards. This paper presents a systems analytical perspective on management options that could efficiently improve air quality at the urban scale, having Delhi as a case study. We employ the newly developed GAINS-City policy analysis framework, consisting of a bottom up emission calculation combined with atmospheric chemistry-transport calculation, to derive innovative insights into the current sources of pollution and their impacts on ambient PM2.5, both from emissions of primary PM as well as precursors of secondary inorganic and organic aerosols. We outline the likely future development of these sources, quantify the related ambient PM2.5 concentrations and health impacts, and explore potential policy interventions that could effectively reduce environmental pollution and resulting health impacts in the coming years. The analysis demonstrates that effective improvement of Delhi's air quality requires collaboration with neighboring States and must involve sources that are less relevant in industrialized countries. At the same time, many of the policy interventions will have multiple co-benefits on development targets in Delhi and its neighboring States. Outcomes of this study, as well as the modelling tools used herein, are applicable to other urban areas and fast growing metropolitan zones in the emerging Asian regions.

Air pollution is one of the most harmful consequences of China's rapid economic development and urbanization. Particularly in the Beijing-Tianjin-Hebei (BTH) regions, particulate matter concentrations have consistently exceeded the national air quality standards. Over the last years, China implemented ambitious measures to reduce emissions from the power, industry and transportation sectors, with notable success during the 11th and 12th Five Year Plan (FYP) periods. However, such strategies appear to be insufficient to reduce the ambient PM2.5 concentration below the National Air Quality Standard of 35 μg m−3 across the BTH region within the next 15 years. We find that a comprehensive mitigation strategy for the residential sector in the BTH region would deliver substantial air quality benefits. Beyond the already planned expansion of district heating and natural gas distribution in urban centers and the foreseen curtailment of coal use for households, such a strategy would redirect some natural gas from power generation units towards the residential sector. Rural households would replace biomass for cooking by liquid petroleum gas (LPG) and electricity, and substitute coal for heating by briquettes. Jointly, these measures could reduce the primary PM2.5 and SO2 emissions by 28% and 11%, respectively, and the population-weighted PM2.5 concentrations by 13%, i.e., from 68 μg m−3 to 59 μg m−3. We estimate that such a strategy would reduce premature deaths attributable to ambient and indoor air pollution by almost one third. Keywords: Solid fuel substitution, PM2.5, Natural gas, Human exposure, Outdoor and indoor health benefits

Over the last decades, energy and pollution control policies combined with structural changes in the economy decoupled emission trends from economic growth, increasingly also in the developing world. It is found that effective implementation of the presently decided national pollution control regulations should allow further economic growth without major deterioration of ambient air quality, but will not be enough to reduce pollution levels in many world regions. A combination of ambitious policies focusing on pollution controls, energy and climate, agricultural production systems and addressing human consumption habits could drastically improve air quality throughout the world. By 2040, mean population exposure to PM2.5 from anthropogenic sources could be reduced by about 75% relative to 2015 and brought well below the WHO guideline in large areas of the world. While the implementation of the proposed technical measures is likely to be technically feasible in the future, the transformative changes of current practices will require strong political will, supported by a full appreciation of the multiple benefits. Improved air quality would avoid a large share of the current 3–9 million cases of premature deaths annually. At the same time, the measures that deliver clean air would also significantly reduce emissions of greenhouse gases and contribute to multiple UN sustainable development goals. This article is part of a discussion meeting issue ‘Air quality, past present and future’.

In recognition of the negative climate change and deteriorative air quality, the iron and steel industry in China was subject to production capacity phase-out policy (PCPP), which is deeply influencing industrial restructuring and national emission reduction targets. However, researches that quantitatively estimated the comprehensive impacts of such structural adjustment policy remain scant. For this purpose, this study expands and soft-links between GAINS and IMED models to characterize the impacts of climate change and PM[Formula: see text]-attributed health co-benefits. Results showed the PCPP based on scale limitation to eliminate backward capacities in the Beijing-Tianjin-Hebei region yields total benefits of 34.9 billion Yuan (4.2 billion USD), 89% of total coming from energy saving and carbon mitigation, more than policy costs (20.0 billion Yuan) in 2020, but the gap between benefit-cost will keep narrowing to [Formula: see text]2.8 billion Yuan ([Formula: see text]0.3 billion USD) in 2020–2030, indicating that policy improvement is needed in the long run. To further increase policy co-benefits and achieve multiple policy targets, the policymaker should readjust the PCPP by switching scale limitation to energy efficiency constraint. If doing that, the difference of benefit-cost will achieve 42.5 billion Yuan (5.1 billion USD). The regional disparity also exits due to the diverse ratio of benefit-cost in the selected provinces, calling for necessary fiscal incentives to the less developed area, e.g., Hebei, to promote closer integration.

In this study we present a dynamic model evaluation of chemistry transport model LOTOS-EUROS (LOng Term Ozone Simulation – EURopean Operational Smog) to analyse the ability of the model to reproduce observed non-linear responses to emission changes and interannual variability of secondary inorganic aerosol (SIA) and its precursors over Europe from 1990 to 2009. The 20 year simulation was performed using a consistent set of meteorological data provided by RACMO2 (Regional Atmospheric Climate MOdel). Observations at European rural background sites have been used as a reference for the model evaluation. To ensure the consistency of the used observational data, stringent selection criteria were applied, including a comprehensive visual screening to remove suspicious data from the analysis. The LOTOS-EUROS model was able to capture a large part of the seasonal and interannual variability of SIA and its precursors' concentrations. The dynamic evaluation has shown that the model is able to simulate the declining trends observed for all considered sulfur and nitrogen components following the implementation of emission abatement strategies for SIA precursors over Europe. Both the observations and the model show the largest part of the decline in the 1990s, while smaller concentration changes and an increasing number of non-significant trends are observed and modelled between 2000 and 2009. Furthermore, the results confirm former studies showing that the observed trends in sulfate and total nitrate concentrations from 1990 to 2009 are lower than the trends in precursor emissions and precursor concentrations. The model captured well these non-linear responses to the emission changes. Using the LOTOS-EUROS source apportionment module, trends in the formation efficiency of SIA have been quantified for four European regions. The exercise has revealed a 20–50% more efficient sulfate formation in 2009 compared to 1990 and an up to 20% more efficient nitrate formation per unit nitrogen oxide emission, which added to the explanation of the non-linear responses. However, we have also identified some weaknesses in the model and the input data. LOTOS-EUROS underestimates the observed nitrogen dioxide concentrations throughout the whole time period, while it overestimates the observed nitrogen dioxide concentration trends. Moreover, model results suggest that the emission information of the early 1990s used in this study needs to be improved concerning magnitude and spatial distribution.

Bottom-up emission inventories provide primary understanding of sources of air pollution and essential input of chemical transport models. Focusing on SO2 and NOx, we conducted a comprehensive evaluation of two widely-used anthropogenic emission inventories over China, ECLIPSE and MIX, to explore the potential sources of uncertainties and find the clues in improving emission inventories. We first compared the activity rates and emission factors used in two inventories, and investigated the reasons of differences and the impacts on emission estimates. We found that SO2 emission estimates are consistent between two inventories (with 1 % differences), while NOx emissions in ECLIPSE's estimates are 16 % lower than those of MIX. Discrepancies at sectorial and provincial level are much higher. We then examined the impacts of different inventories on model performance, by using the nested GEOS-Chem model. We finally derived top-down NOx emissions by using the NO2 columns from the Ozone Monitoring Instrument (OMI) and compared with the bottom-up estimates. To our knowledge, this is the first work where source-sector comparisons are made along with the remote sensing retrievals and chemical transport modeling. Through the comparison between bottom-up emission inventories and evaluation with top-down information, we summarized the potential directions for further improvement in inventory development.

Industrial processes currently contribute 40% to global CO2 emissions and therefore substantial increases in industrial energy efficiency are required for reaching the 2 °C target. We assess the macroeconomic effects of deploying low carbon technologies in six energy intensive industrial sectors (Petroleum, Iron and Steel, Non-metallic Minerals, Paper and Pulp, Chemicals, and Electricity) in Europe, China and India in 2030. By combining the GAINS technology model with a macroeconomic computable general equilibrium model, we find that output in energy intensive industries declines in Europe by 6% in total, while output increases in China by 11% and in India by 13%. The opposite output effects emerge because low carbon technologies lead to cost savings in China and India but not in Europe. Consequently, the competitiveness of energy intensive industries is improved in China and India relative to Europe, leading to higher exports to Europe. In all regions, the decarbonization of electricity plays the dominant role for mitigation. We find a rebound effect in China and India, in the size of 42% and 34% CO2 reduction, respectively, but not in Europe. Our results indicate that the range of considered low-carbon technology options is not competitive in the European industrial sectors. To foster breakthrough low carbon technologies and maintain industrial competitiveness, targeted technology policy is therefore needed to supplement carbon pricing.

Strong economic growth in China has fueled development of cities where increase in energy demand and transportation lead to severe air pollution. The cities contribute also a significant share of the national greenhouse gas emissions. We identify strong synergies between air quality and climate relevant measures that would allow improving cost-efficiency of air pollution policies. In order to help local policy makers to identify viable and efficient solutions, we developed a city-scale emission model (GAINS-City) based on the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model developed by the International Institute for Applied Systems Analysis (IIASA, Austria). The GAINS-City model relies on a technology-based approach to evaluate the co-benefits of various policies. This approach allows for estimation of emission reductions of several pollutants (including SO2, NOX, PM) and CO2 for individual policies and support evaluation of co-benefits. In addition, a reduction index, an integrated rank of the individual reductions potential, was defined to recommend the priority of policies implementation. The approach will have great potential to be applied in many large cities with local input data and/or minor structure modifications. We conducted a case study in Beijing to demonstrate the model features. Based on the technology-based evaluation approach, policy packages were designed and implemented in policy scenarios. The emissions under three scenarios (Baseline, Air Quality, and Strict Air Quality) in base year (2005) and future years (2020 and 2030) were estimated. The results indicate a significant reduction potential. In 2030, implementation of Air Quality and Strict Air Quality scenarios could result in reductions of 39–48% of SO2 emissions, 38–42% of NOX emissions, 37–55% of PM2.5 emissions and 5–22% of CO2 emissions respectively, compared with the Baseline scenario. The results demonstrated air quality policies and measures could also have co-benefits of reducing CO2 emissions. However, there is no significant difference of reductions between the two policy scenarios, which indicates the limited further reduction potential in the stricter air quality case. This calls for a wider application of cleaner technologies, such as IGCC and CCS, and more aggressive air quality measures by neighboring provinces to control regional air pollution.

This paper discusses the impact of air quality and climate policies on global mercury emissions in the time horizon up to 2050. Evolution of mercury emissions is based on projections of energy consumption for a scenario without any global greenhouse gas mitigation efforts, and for a 2 °C climate policy scenario, which assumes internationally coordinated action to mitigate climate change. The assessment takes into account current air quality legislation in each country, as well as provides estimates of maximum feasible reductions in mercury through 2050. Results indicate significant scope for co-benefits of climate policies for mercury emissions. Atmospheric releases of mercury from anthropogenic sources under the global climate mitigation regime are reduced in 2050 by 45% when compared to the case without climate measures. Around one third of world-wide co-benefits for mercury emissions by 2050 occur in China. An annual Hg-abatement of about 800 tons is estimated for the coal combustion in power sector if the current air pollution legislation and climate policies are adopted in parallel.

Nitrogen oxides (NOx) are key pollutants for the improvement of ambient air quality. Within this study we estimated the historical NOx emissions in China for the period 1995–2010, and calculated future NOx emissions every five years until 2030 under six emission scenarios. Driven by the fast growth of energy consumption, we estimate the NOx emissions in China increased rapidly from 11.0 Mt in 1995 to 26.1 Mt in 2010. Power plants, industry and transportation were major sources of NOx emissions, accounting for 28.4%, 34.0%, and 25.4% of the total NOx emissions in 2010, respectively. Two energy scenarios, a business as usual scenario (BAU) and an alternative policy scenario (PC), were developed to project future energy consumption. In 2030, total energy consumption is projected to increase by 64% and 27% from 2010 level respectively. Three sets of end-of-pipe pollution control measures, including baseline, progressive, and stringent control case, were developed for each energy scenario, thereby constituting six emission scenarios. By 2030, the total NOx emissions are projected to increase (compared to 2010) by 36% in the baseline while policy cases result in reduction up to 61% in the most ambitious case with stringent control measures. More than a third of the reduction achieved by 2030 between least and most ambitious scenario comes from power sector, and more than half is distributed equally between industry and transportation sectors. Selective catalytic reduction dominates the NOx emission reductions in power plants, while life style changes, control measures for industrial boilers and cement production are major contributors to reductions in industry. Timely enforcement of legislation on heavy-duty vehicles would contribute significantly to NOx emission reductions. About 30% of the NOx emission reduction in 2020 and 40% of the NOx emission reduction in 2030 could be treated as the ancillary benefit of energy conservation. Sensitivity analysis was conducted to explore the impact of key factors on future emissions.

Using the GAINS (Greenhouse Gas–Air Pollution Interactions and Synergies) model, we derived Annex I marginal abatement cost curves for the years 2020 and 2030 for three World Energy Outlook baseline scenarios (2007–2009) of the International Energy Agency. These cost curves are presented by country, by greenhouse gas and by sector. They are available for further inter-country comparisons in the GAINS Mitigation Efforts Calculator—a free online tool. We illustrate the influence of the baseline scenario on the shape of mitigation cost curves, and identify key low cost options as well as no-regret priority investment areas for the years 2010–2030. Finally, we show the co-effect of GHG mitigation on the emissions of local air pollutants and argue that these co-benefits offer strong local incentives for mitigation.

Environmental policies in Europe have successfully eliminated the most visible and immediate harmful effects of air pollution in the last decades. However, there is ample and robust scientific evidence that even at present rates Europe's emissions to the atmosphere pose a significant threat to human health, ecosystems and the global climate, though in a less visible and immediate way. As many of the 'low hanging fruits' have been harvested by now, further action will place higher demands on economic resources, especially at a time when resources are strained by an economic crisis. In addition, interactions and interdependencies of the various measures could even lead to counter-productive outcomes of strategies if they are ignored. Integrated assessment models, such as the GAINS (Greenhouse gas - Air pollution Interactions and Synergies) model, have been developed to identify portfolios of measures that improve air quality and reduce greenhouse gas emissions at least cost. Such models bring together scientific knowledge and quality-controlled data on future socio-economic driving forces of emissions, on the technical and economic features of the available emission control options, on the chemical transformation and dispersion of pollutants in the atmosphere, and the resulting impacts on human health and the environment. The GAINS model and its predecessor have been used to inform the key negotiations on air pollution control agreements in Europe during the last two decades. This paper describes the methodological approach of the GAINS model and its components. It presents a recent policy analysis that explores the likely future development of emissions and air quality in Europe in the absence of further policy measures, and assesses the potential and costs for further environmental improvements. To inform the forthcoming negotiations on the revision of the Gothenburg Protocol of the Convention on Long-range Transboundary Air Pollution, the paper discusses the implications of alternative formulations of environmental policy targets on a cost-effective allocation of further mitigation measures.

An integrated emission inventory of China was validated through comparing the Community Multi-scale Air Quality (CMAQ) simulations with the NO2 and SO2 column retrieved from Ozone Monitoring Instrument (OMI), Aerosol Optical Depth (AOD) retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS), and ground observations of SO2 ,N O2 ,P M10 ,P M2.5 and its components. The model simulations were performed for year 2005. The model generally reproduces both spatial distribution and seasonal variation of tropospheric NO2 ,S O2 column densities and AOD in China that have been observed by OMI and MODIS. The correlation coefficients between model simulated and satellite observed NO2 column densities, SO2 column densities and AOD over east China are 0.90, 0.85 and 0.79, and the normalized mean bias (NMBs) are � 8%, 1%, and � 8% respectively, which are comparable with the errors from satellite retrievals. The surface concentrations of NO2 ,S O2, and PM10 given by CMAQ model are also comparable with those observed in Beijing, Shanghai, and Guangzhou, with the NMBs ranging from 1% to 18%, � 3% to � 25%, and � 12% to 18%, respectively. The results suggest that the anthropogenic emissions of SO2, NOx, and PM10 used in this study are in line with both the satellite and ground observations therefore are of acceptable accuracy. There is overestimation for SO2 and underestimation for PM10 in some industry-intensive areas because of the inaccuracy of spatial and temporal allocations. The CMAQ model also significantly underestimates the PM2.5 concentration in Beijhjing, mainly due to the limitation of secondary organic aerosol (SOA) formation mechanism used in the model and the underestimation of primary OC and EC emissions. Therefore more efforts shall be made to improve the primary emission estimates of OC and EC, as well as the temporal allocation factor of SO2 and PM10 emissions.

Anthropogenic emissions of air pollutants in China influence not only local and regional environments but also the global atmospheric environment; therefore, it is important to understand how China's air pollutant emissions will change and how they will affect regional air quality in the future. Emission scenarios in 2020 were projected using forecasts of energy consumption and emission control strategies based on emissions in 2005, and on recent development plans for key industries in China. We developed four emission scenarios: REF[0] (current control legislations and implementation status), PC[0] (improvement of energy efficiencies and current environmental legislation), PC[1] (improvement of energy efficiencies and better implementation of environmental legislation), and PC[2] (improvement of energy efficiencies and strict environmental legislation). Under the REF[0] scenario, the emission of SO2, NOx, VOC and NH3 will increase by 17%, 50%, 49% and 18% in 2020, while PM10 emissions will be reduced by 10% over East China, compared to that in 2005. In PC[2], sustainable energy polices will reduce SO2, NOx and PM10 emissions by 4.1 Tg, 2.6 Tg and 1.8 Tg, respectively; better implementation of current control policies will reduce SO2, NOx and PM10 emission by 2.9 Tg, 1.8 Tg, and 1.4 Tg, respectively; strict emission standards will reduce SO2, NOx and PM10 emissions by 3.2 Tg, 3.9 Tg, and 1.7 Tg, respectively. Under the PC[2] scenario, SO2 and PM10 emissions will decrease by 18% and 38%, while NOx and VOC emissions will increase by 3% and 8%, compared to that in 2005. Future air quality in China was simulated using the Community Multi-scale Air Quality Model (CMAQ). Under REF[0] emissions, compared to 2005, the surface concentrations of SO2, NO2, hourly maximum ozone in summer, PM2.5, total sulfur and nitrogen depositions will increase by 28%, 41%, 8%, 8%, 19% and 25%, respectively, over east China. Under the PC[2] emission scenario, the surface concentrations of SO2, PM2.5, total sulfur depositions will decrease by 18%, 16% and 15%, respectively, and the surface concentrations of NO2, nitrate, hourly maximum ozone in summer, total nitrogen depositions will be kept as 2005 level, over east China. The individual impacts of SO2, NOx, NH3, NMVOC and primary PM emission changes on ozone and PM2.5 concentrations have been analyzed using sensitivity analysis. The results suggest that NOx emission control need to be enhanced during the summertime to obtain both ozone and PM2.5 reduction benefits. NH3 emission controls should also be considered in order to reduce both nitrate concentration and total nitrogen deposition in the future.

An emission inventory of non-methane volatile organic compounds (NMVOCs) from anthropogenic sources in China was compiled for the year 2005. The NMVOC emissions were 20.1 Tg, of which industrial and domestic solvent use, road transportation, and bio-fuel combustion contributed 28.6%, 23.4%, and 18.0%, respectively. Emissions were speciated into 40 species according to their atmospheric photochemical reactivity, toxicity, and model applicability. Of the total emissions, alkanes account for 29.8%, followed by aromatics (21.9%), alkenes and alkynes (21.0%), and carbonyls (17.8%). Emissions at the provincial level were spatially allocated onto grids with a resolution of 36 km×36 km, according to population distribution. Furthermore, the provincial and sectoral emissions of nine toxic species, including n -hexane, 1,3-butadiene, styrene, benzene, toluene, xylene, methanol, formaldehyde, and acraldehyde, are also analyzed. Finally, the national total emissions were considered with an uncertainty of [−44%,+109%] in 95% confidence interval, by using the Monte Carlo method.

We have used a global version of the Regional Air Pollution Information and Simulation (RAINS) model to estimate anthropogenic emissions of the air pollution precursors sulphur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), primary carbonaceous particles of black carbon (BC), organic carbon (OC) and methane (CH4). We developed two scenarios to constrain the possible range of future emissions. As a baseline, we investigated the future emission levels that would result from the implementation of the already adopted emission control legislation in each country, based on the current national expectations of economic development. Alternatively, we explored the lowest emission levels that could be achieved with the most advanced emission control technologies that are on the market today. This paper describes data sources and our assumptions on activity data, emission factors and the penetration of pollution control measures. We estimate that, with current expectations on future economic development and with the present air quality legislation, global anthropogenic emissions of SO2 and NOx would slightly decrease between 2000 and 2030. For carbonaceous particles and CO, reductions between 20% and 35% are computed, while for CH4 an increase of about 50% is calculated. Full application of currently available emission control technologies, however, could achieve substantially lower emissions levels, with decreases up to 30% for CH4, 40% for CO and BC, and nearly 80% for SO2.

International audience; This article proposes a new method to assess the health impact of populations exposed to fine particles (PM2.5) during their whole lifetime, which is suitable for comparative analysis of energy scenarios. The method takes into account the variation of particle concentrations over time as well as the evolution of population cohorts. Its capabilities are demonstrated for two pathways of European energy system development up to 2050: the Baseline (BL) and the Low Carbon, Maximum Renewable Power (LC-MRP). These pathways were combined with three sets of assumptions about emission control measures: Current Legislation (CLE), Fixed Emission Factors (FEFs), and the Maximum Technically Feasible Reductions (MTFRs). Analysis was carried out for 45 European countries. Average PM2.5 concentration over Europe in the LC-MRP/CLE scenario is reduced by 58% compared with the BL/FEF case. Health impacts (expressed in days of loss of life expectancy) decrease by 21%. For the LC-MRP/MTFR scenario the average PM2.5 concentration is reduced by 85% and the health impact by 34%. The methodology was developed within the framework of the EU's FP7 EnerGEO project and was implemented in the Platform of Integrated Assessment (PIA). The Platform enables performing health impact assessments for various energy scenarios.

We present a systematic comparison of tropospheric NO2 from 17 global atmospheric chemistry models with three state-of-the-art retrievals from the Global Ozone Monitoring Experiment (GOME) for the year 2000. The models used constant anthropogenic emissions from IIASA/EDGAR3.2 and monthly emissions from biomass burning based on the 1997–2002 average carbon emissions from the Global Fire Emissions Database (GFED). Model output is analyzed at 10:30 local time, close to the overpass time of the ERS-2 satellite, and collocated with the measurements to account for sampling biases due to incomplete spatiotemporal coverage of the instrument. We assessed the importance of different contributions to the sampling bias: correlations on seasonal time scale give rise to a positive bias of 30–50% in the retrieved annual means over regions dominated by emissions from biomass burning. Over the industrial regions of the eastern United States, Europe and eastern China the retrieved annual means have a negative bias with significant contributions (between –25% and +10% of the NO2 column) resulting from correlations on time scales from a day to a month. We present global maps of modeled and retrieved annual mean NO2 column densities, together with the corresponding ensemble means and standard deviations for models and retrievals. The spatial correlation between the individual models and retrievals are high, typically in the range 0.81–0.93 after smoothing the data to a common resolution. On average the models underestimate the retrievals in industrial regions, especially over eastern China and over the Highveld region of South Africa, and overestimate the retrievals in regions dominated by biomass burning during the dry season. The discrepancy over South America south of the Amazon disappears when we use the GFED emissions specific to the year 2000. The seasonal cycle is analyzed in detail for eight different continental regions. Over regions dominated by biomass burning, the timing of the seasonal cycle is generally well reproduced by the models. However, over Central Africa south of the Equator the models peak one to two months earlier than the retrievals. We further evaluate a recent proposal to reduce the NOx emission factors for savanna fires by 40% and find that this leads to an improvement of the amplitude of the seasonal cycle over the biomass burning regions of Northern and Central Africa. In these regions the models tend to underestimate the retrievals during the wet season, suggesting that the soil emissions are higher than assumed in the models. In general, the discrepancies between models and retrievals cannot be explained by a priori profile assumptions made in the retrievals, neither by diurnal variations in anthropogenic emissions, which lead to a marginal reduction of the NO2 abundance at 10:30 local time (by 2.5–4.1% over Europe). Overall, there are significant differences among the various models and, in particular, among the three retrievals. The discrepancies among the retrievals (10–50% in the annual mean over polluted regions) indicate that the previously estimated retrieval uncertainties have a large systematic component. Our findings imply that top-down estimations of NOx emissions from satellite retrievals of tropospheric NO2 are strongly dependent on the choice of model and retrieval.

Air quality, ecosystem exposure to nitrogen deposition, and climate change are intimately coupled problems: we assess changes in the global atmospheric environment between 2000 and 2030 using 26 state-of-the-art global atmospheric chemistry models and three different emissions scenarios. The first (CLE) scenario reflects implementation of current air quality legislation around the world, while the second (MFR) represents a more optimistic case in which all currently feasible technologies are applied to achieve maximum emission reductions. We contrast these scenarios with the more pessimistic IPCC SRES A2 scenario. Ensemble simulations for the year 2000 are consistent among models and show a reasonable agreement with surface ozone, wet deposition, and NO2 satellite observations. Large parts of the world are currently exposed to high ozone concentrations and high deposition of nitrogen to ecosystems. By 2030, global surface ozone is calculated to increase globally by 1.5 +/- 1.2 ppb (CLE) and 4.3 +/- 2.2 ppb (A2), using the ensemble mean model results and associated +/- 1 sigma standard deviations. Only the progressive MFR scenario will reduce ozone, by -2.3 +/- 1.1 ppb. Climate change is expected to modify surface ozone by -0.8 +/- 0.6 ppb, with larger decreases over sea than over land. Radiative forcing by ozone increases by 63 +/- 15 and 155 +/- 37 mW m(-2) for CLE and A2, respectively, and decreases by -45 +/- 15 mW m(-2) for MFR. We compute that at present 10.1% of the global natural terrestrial ecosystems are exposed to nitrogen deposition above a critical load of 1 g N m(-2) yr(-1). These percentages increase by 2030 to 15.8% (CLE), 10.5% (MFR), and 25% (A2). This study shows the importance of enforcing current worldwide air quality legislation and the major benefits of going further. Nonattainment of these air quality policy objectives, such as expressed by the SRES-A2 scenario, would further degrade the global atmospheric environment.

An integrated approach to climate change and regional air pollution can harvest considerable ancillary benefits in terms of environmental impacts and costs. This is because both problems are caused to a large extent by the same activity (fossil fuel combustion). Substantial ancillary benefits were found for regional air pollution (SO2, NOx, VOC and particulate matter) of implementing the Kyoto Protocol (intended to control greenhouse gas emissions) in Europe. For instance, while three different scenarios on Kyoto implementation were found to reduce European CO2 emissions by 4–7%, they also reduced European emissions of SO2 by 5–14% compared with a no Kyoto policies case. The magnitude of ancillary benefits depends on how flexible mechanisms and surplus emission allowances are used in meeting the Kyoto targets. The total cost savings for implementing current policies for regional air pollution of the Kyoto Protocol are of an order of 2.5–7 billion Euro. In all cases, this is in the order of half the costs of the climate policy (4–12 billion Euro). Using flexible mechanisms reduces emissions of air pollutants for Europe as a whole even further than domestic implementation (e.g. 10–14% versus 5% for SO2 emissions), but the reductions are shifted from Western Europe to Central and Eastern Europe and Russia. The use of surplus emission allowances to achieve the Kyoto targets decreases the ancillary benefits, in particular for the latter group of countries (e.g. unprotected area against acidification increases from 1.3 to 1.7 million ha).

A global 3-D chemistry-transport model STOCHEM has been employed to study trends in the mole fractions of methane, carbon monoxide and ozone in baseline air masses entering Europe from the Atlantic Ocean over the period from 1990 to 2030. With a range of emission scenarios for man-made ozone precursor emission sources available, a wide range of model trends were predicted for the period up to 2030. In the scenario based on current planned air pollution controls, IIASA CLE, methane shows a strong upward trend, ozone shows a weaker upward trend, and carbon monoxide is approximately flat in baseline air masses. In one of the more pessimistic IPCC SRES scenarios, A2, all three gases show future increases. However, in the scenario based on maximum feasible emission reductions, IIASA MFR all three trace gases decline. By 2030, projected climate change reduces the growth in CH4, but has insignificant effects on baseline CO and O3 in these simulations. Global or hemispheric ozone precursor emissions and their controls exert a potentially large external influence on Europe’s air quality. This influence is currently not taken into account in future European air quality policy formulation. r 2005 Elsevier Ltd. All rights reserved.

Inventories for global aerosol and aerosol precursor emissions have been collected (based on published inventories and published simulations), assessed and prepared for the year 2000 (present-day conditions) and for the year 1750 (pre-industrial conditions). These global datasets establish a comprehensive source for emission input to global modeling, when simulating the aerosol impact on climate with state-of-the-art aerosol component modules. As these modules stratify aerosol into dust, sea-salt, sulfate, organic matter and soot, for all these aerosol types global fields on emission strength and recommendations for injection altitude and particulate size are provided. Temporal resolution varies between daily (dust and sea-salt), monthly (wild-land fires) and annual (all other emissions). These datasets benchmark aerosol emissions according to the knowledge in the year 2004. They are intended to serve as systematic constraints in sensitivity studies of the AeroCom initiative, which seeks to quantify (actual) uncertainties in aerosol global modeling.

Uncertainty is a critical issue for all models that attempt to quantify the necessary emission reductions that are required to meet environmental quality targets. This paper discusses a methodology specifically developed to analyse the uncertainties in the emission estimates with the regional air pollution information and simulation (RAINS) integrated assessment model, considering the uncertainties in the model parameters themselves. Overall, it was found that a typical range of uncertainties for modeled national emissions of sulfur dioxide, nitrogen oxides and ammonia in Europe lies between 10 and 30%. In general, the uncertainties are strongly dependent on the potential for error compensation. This compensation potential is larger (and uncertainties are smaller) if calculated emissions are composed of a larger number of equal-sized source categories, where the errors in input parameters are not correlated with each other. Thus, estimates of the national total emissions are generally more certain than estimates of sectoral emissions. A sensitivity analysis with respect to the uncertainty in input parameters showed that the actual uncertainties are critically influenced by the specific situation (pollutant, year, country). However, the emission factor is an important contributor to the uncertainty in estimates of historical emissions, while uncertainty in the activity data dominates the future estimates.

Despite recent efforts to limit the growth of SO2 emissions in Asia, the negative environmental effects of sulphur emissions are likely to further increase in the future. This paper presents an extension of the RAINS-Asia integrated assessment model for acidification in Asia with an optimisation routine that can be used to identify cost-effective emission control strategies that achieve environmental targets for ambient SO2 concentrations and sulphur deposition at least costs. Example scenarios developed with this optimisation module demonstrate a potential for significant cost savings in Asia, if emission controls are allocated to those sources that have the largest environmental impact and are cheapest to control. It is shown that strategies that simultaneously address harmful population exposure and the risk of vegetation damage from acid deposition result in the most cost-effective use of resources spent for emission controls. (C) 2004 Elsevier Ltd. All rights reserved.

Inventories of emissions of non-methane volatile organic compounds (NMVOC) in China are reported for the years 1990, 1995, 2000, 2010, and 2020. For 1990 and 1995, historical activity data were assembled for more than 70 processes that lead to the release of NMVOC. Appropriate emission factors were developed, based on Western, Asian and Chinese experience. It is estimated that emissions were 11.1 Tg in 1990 and 13.1 Tg in 1995, principally from the combustion of biofuels and coal in small combustors. All emissions are presented at provincial level. Using appropriate growth factors derived from anticipated economic, population, and lifestyle changes, and factoring in regulatory changes and technology improvements, we estimate that emissions could grow to 15.6 Tg in 2000, 17.2 Tg in 2010, and 18.2 Tg in 2020. Though activity growth rates are much higher than these increases would imply, technology improvements mediate the increases. Emissions from solvent use, paint use, and transport become increasingly important as time goes on. The sectoral distribution and per capita level of China's emissions are compared with those of other countries. Finally, gridded NMVOC emission fields are presented at 1°×1° resolution, and speciation of the emissions into 16 chemical types is reported.

This paper compares three scenarios of energy demand in the European Union until 2010 and analyses their effects on carbon emissions as well as their impacts on the precursor emissions for acidification and ground-level ozone. The analysis links the results of energy model PRIMES with the integrated environmental assessment model RAINS. Important synergies between climate change policies and policies to control regional air pollution have been identified. Mitigation of acidification and ozone according to the current EU strategy will be easier and cheaper if the Kyoto targets for the reduction of the emissions of greenhouse gases (GHG) are to be met. In case when the Kyoto target needs to be achieved by individual EU member countries without trading in CO2 emission rights, the costs of controlling the pollutants contributing to acidification and ground-level ozone can be up to 10% lower than for the baseline scenario which does not assume any climate change policies. Although lower, the effects are also important if trading in carbon emission rights is allowed. These cost savings compensate up to 20% of higher costs of energy supplies in the EU and associated with them welfare losses caused by the necessity to meet the carbon constraint.

Starting from an inventory of SO2, NOx, VOC and NH3 emissions for the years 1990 and 1995 in East Asia (Japan, South and North Korea, China, Mongolia and Taiwan), the temporal development of the emissions of the four air pollutants is projected to the year 2030 based on scenarios of economic development. The projections are prepared at a regional level (prefectures or provinces of individual countries) and distinguish more than 100 source categories for each region. The emission estimates are presented with a spatial resolution of 1×1 degree longitude/latitude. First results suggest that, due to the emission control legislation taken in the region, SO2 emissions would only grow by about 46 percent until 2030. Emissions of NOx and VOC may increase by 95 and 65 percent, respectively, mainly driven by the expected increase in road traffic volume. Ammonia, mainly emitted from agriculture, is projected to double by 2030.

Primary particulate matter is emitted directly into the atmosphere from various anthropogenic and natural sources such as power plants (combustion of fossil fuels) or forest fires. Secondary particles are formed by transformation of SO2, NOx, NH3, and VOC in the atmosphere. They both contribute to ambient particulate matter concentrations, which may have adverse effects on human health. Health hazards are caused by small particulate size, high number of especially fine (< 2.5 µm) and ultra-fine (< 0.1 µm) particles and/or their chemical composition. As part of an integrated assessment model developed at IIASA, a module on primary particulate matter (PM) emissions has been added to the existing SO2, NOx, NH3 and VOC sections. The module considers so far primary emissions of total suspended particles (TSP), PM10 and PM2.5 from aggregated stationary and mobile sources. A primary PM emission database has been established. Country specific emission factors for stationary sources have been calculated within the module using the ash content of solid fuels.

The European Commission has proposed air quality standards for NO2, SO2 and PM10 to be in force by 2010. The present paper presents a study that gauged their costs and benefits. An analysis of the expected emissions for 2010 (reference emission scenario), using simplified air quality models, showed that non-compliance with these standards will occur in cities only, not in rural areas. Most compliance problems are expected for PM10, least for SO2. Central estimates of the costs to meet standards range from 21 MECU (SO2), to 79 MECU (NO2) to 87--225 MECU (PM10). The estimated benefits are 83--3783 MECU (SO2), 408--5900 MECU (NO2), and 5007--51247 MECU (PM10). Uncertainties are high, due to errors and incertitude in various steps of the methodology, mainly the estimation of the human health effects, in particular effects on mortality, and in the valuation of a statistical life. In the case of PM10, additional uncertainty results from the small size of the air quality database. Notwithstanding the uncertainties, the indications are that the benefits exceed the costs.

A methodology for the GIS (Geographic Information System) based analysis of DH (District Heating) potentials is introduced and applied to the continental United States. The energy demand for space heating and hot water in the residential and commercial sector is assessed and spatially allocated using high resolution population distribution and land use data. Demand centers are identified and the overall heat demand and its density are extracted. For each of some 4800 agglomerations, average heat distribution costs are calculated and a CHP (combined heat and power) plant suitable in technology and capacity is selected. The results suggest that there is substantial potential for an extension of DH in the United States. Especially in the north eastern part of the country, a significant share of the demand is located in areas of high demand density. Heat distribution costs vary considerably, and are on average slightly lower in greater agglomerations and regions with high specific heat demands. The overall potential, its distribution to geographical regions and CHP technologies, as well as the average heat distribution costs are found to be strongly dependent on the assumed minimum heat demand density applied to classify the grid cells according their suitability for DH.