Air Pollution Abatement Policies Research Articles

Transdisciplinary Research as a Means of Protecting Human Health, Ecosystems and Climate by Engaging People to Act on Air Pollution

Abstract Air pollution harms the health of humans, nature and wildlife, agricultural crops and livestock and climate. As a result, it hinders the attainment of Sustainable Development Goals 3 (Good Health and Wellbeing), 7 (Affordable and Clean Energy), 11 (Sustainable Cities and Communities) and 13 (Climate Change). In order to improve human and (agro-)ecosystem health, One Health approaches for better air quality must account for local knowledge, cultural practices and priorities. People with lower socio-economic status often have limited awareness of air pollution yet are affected most through personal exposure and increased food prices. This case trialled a new, co-created transdisciplinary approach to air pollution awareness raising in the Mukuru community in Nairobi, Kenya. The pilot study used interviews, storytelling, participatory mapping, theatre, playful activities and music with the aim of discovering affected communities’ perceptions of air pollution, increasing understanding and empowering people to demand that policy makers develop and implement effective, inclusive air pollution abatement policies. Information © The Authors 2024

Outdoor Air Pollution and Childhood Respiratory Disease: The Role of Oxidative Stress

The leading mechanisms through which air pollutants exert their damaging effects are the promotion of oxidative stress, the induction of an inflammatory response, and the deregulation of the immune system by reducing its ability to limit infectious agents' spreading. This influence starts in the prenatal age and continues during childhood, the most susceptible period of life, due to a lower efficiency of oxidative damage detoxification, a higher metabolic and breathing rate, and enhanced oxygen consumption per unit of body mass. Air pollution is involved in acute disorders like asthma exacerbations and upper and lower respiratory infections, including bronchiolitis, tuberculosis, and pneumoniae. Pollutants can also contribute to the onset of chronic asthma, and they can lead to a deficit in lung function and growth, long-term respiratory damage, and eventually chronic respiratory illness. Air pollution abatement policies, applied in the last decades, are contributing to mitigating air quality issues, but more efforts should be encouraged to improve acute childhood respiratory disease with possible positive long-term effects on lung function. This narrative review aims to summarize the most recent studies on the links between air pollution and childhood respiratory illness.

Assessing Multiple Inequalities and Air Pollution Abatement Policies

Addressing inequality is recognized a worldwide development objective. The literature has primarily focused on examining economic or social inequality, but rarely on environmental inequality. Centering the discussion on economic or social factors does not provide a holistic view of inequality because it is multidimensional and several facets may overlap imposing a disproportionate burden on vulnerable communities. This study investigates the magnitude of air quality inequality in conjunction with economic and social inequalities in Bogotá (Colombia). It explores where inequalities overlap and assesses alleviation measures by tackling air pollution. We develop a composite index to estimate performance in socioeconomic and air quality characteristics across the city and evaluate inequality with a variety of measures. Using an atmospheric chemical transport model, we simulate the impact of three air pollution abatement policies: paving roads, industry fuel substitution, and diesel-vehicle renewal on fine particle concentrations, and compute their effect on inequality. Results show that allocation of air quality across Bogotá is highly unequal, exceeding economic or social inequality. Evidence also indicates that economic, social and air quality disparities intersect, displaying the southwest as the most vulnerable zone. Paving roads is found to be the most progressive and cost-effective policy, reducing overall inequality between 11 and 46 percent with net benefits exceeding US$1.4 billion.

Political differences in air pollution abatement under the Clean Air Act

In this paper, we study how local politics affect state level implementation of a critical federal environmental policy, the Clean Air Act, in the electricity generation sector. The analysis focuses on the installation of capital intensive air pollution abatement technology in highly regulated “nonattainment” areas, which violate federal air quality standards. The primary research design uses a regression discontinuity in the vote share for Republican governors and event study analyses of close elections. In nonattainment areas, Republican gubernatorial control differentially decreases new air pollution abatement capital spending by 90% and the probability of installing the most effective nitrogen oxide abatement technology by nine percentage points, relative to attainment areas and the counterfactual of Democratic gubernatorial control. The health benefits from reduced nitrogen oxide emissions in nonattainment areas likely exceed the additional costs of new air pollution abatement technology at electric utilities. However, the estimated benefit-cost ratios are smaller than those from many other air pollution abatement policies and net benefits may be negative for technology that will operate for fewer than five years.

The cost of inaction in air pollution abatement policies

Two alternative air quality policies are compared: one is the application of only mandatory abatement measures from 2020 to 2030. The second is the definition of a more active and locally-based policy that will lead to a better air quality at the end of the decade. Using an integrated modelling system, we demonstrate that the active policy is quite more convenient from the economic viewpoint, at least for the specific situation of the Lombardy region, considered in the study. Improving particulate matter concentrations may however produce worse ozone values. A full view of all pollutants is thus necessary when planning for air quality at regional level.

Quantifying the impact of ozone on crops in Sub-Saharan Africa demonstrates regional and local hotspots of production loss.

Tropospheric ozone can have a detrimental effect on vegetation, including reducing the quantity of crop yield. This study uses modelled ozone flux values (POD3IAM; phytotoxic ozone dose above 3 nmol m-2 s-1, parameterised for integrated assessment modelling) for 2015, together with species-specific flux-effect relationships, spatial data on production and growing season dates to quantify the impact of ozone on the production of common wheat (Triticum aestivum) and common beans (Phaseolus vulgaris) across Sub-Saharan Africa (SSA). A case study for South Africa was also done using detailed data per province. Results suggest that ozone pollution could decrease wheat yield by between 2 and 13%, with a total annual loss of 453,000 t across SSA. The impact on bean production depended on the season; however, estimated yield losses were up to 21% in some areas of SSA, with an annual loss of ~300,000 t for each of the two main growing seasons. Production losses tended to be greater in countries with the highest production, for example, Ethiopia (wheat) and Tanzania (beans). This study provides an indication of the location of areas at high risk of crop losses due to ozone. Results emphasise that efforts to reduce ozone precursors could contribute to reducing the yield gap in SSA. More stringent air pollution abatement policies are required to reduce crop losses to ozone in the future.

Assessing Multiple Inequalities and Air Pollution Abatement Policies

Addressing inequality is recognized a worldwide development objective. The literature has primarily focused on examining economic or social inequality, but rarely on environmental inequality. Since inequality is multidimensional, several facets may overlap imposing a disproportionate burden on vulnerable communities. This study investigates the magnitude of air-quality inequality in conjunction with economic and social inequalities in Bogota (Colombia). It explores where inequalities overlap and assesses alleviation measures by tackling air pollution. We develop a composite index to estimate performance in socioeconomic and air quality characteristics across the city and evaluate inequality with a variety of measures. Using an atmospheric-chemical transport model, we simulate the impact of three air pollution abatement policies: paving roads, industry fuel substitution, and diesel-vehicle renewal on fine particle concentrations, and compute their effect on inequality. Results show that allocation of air-quality across Bogota is highly unequal, exceeding economic or social inequality. Evidence indicates economic, social and air quality disparities intersect displaying southwest as the most vulnerable zone. Paving roads is the most progressive and cost-effective policy, reducing overall inequality between 19-84% with net benefits exceeding US$479 million. Our analysis also suggests that benefits of renewing diesel heavy- and light-duty vehicles do not compensate the costs.

Multidecadal trend analysis of in situ aerosol radiative properties around the world

Abstract. In order to assess the evolution of aerosol parameters affecting climate change, a long-term trend analysis of aerosol optical properties was performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann–Kendall (MK) statistical test associated with several pre-whitening methods and with Sen's slope was used as the main trend analysis method. Comparisons with general least mean square associated with autoregressive bootstrap (GLS/ARB) and with standard least mean square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficient trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficient time series also exhibit primarily decreasing trends. For single scattering albedo, 52 % of the sites exhibit statistically significant positive trends, mostly in Asia, eastern/northern Europe and the Arctic, 22 % of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 26 % of sites have trends which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10-year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10-year trends are primarily found for earlier periods (10-year trends ending in 2010–2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10-year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10-year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10-year trends of the scattering coefficient – there is a shift to statistically significant negative trends in 2009–2012 for all stations in the eastern and central USA. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage provides insight into potential aerosol effects on climate changes.

Does China's air pollution abatement policy matter? An assessment of the Beijing-Tianjin-Hebei region based on a multi-regional CGE model

This paper assesses the impact of China's air pollution abatement (APA) policies on both the economy and environment in the Beijing-Tianjin-Hebei (BTH) area, using a multi-regional energy-environment-economy computable general equilibrium (CGE) model incorporating the direct abatement expenditure of the proposed policies.The results show that, over the entire BTH area, the policies could generate an average annual loss of 1.4% of Gross Regional Product growth in the Action Plan scenario and 2.3% in the Enhanced Action Plan scenario. Moreover, realizing the 2020 PM2.5 BTH area concentration targets will not be possible in the Enhanced Action Plan scenario, even with a reduction in emissions of over 60% of sulfur dioxide, nitrogen oxide, and primary PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 µm) and over 30% of VOCS (volatile organic compounds). End-of-pipe control is identified as the most cost-effective policy for most pollutant emission reductions, and that more joint measures are needed in future to address end-of-pipe control and reductions from vehicles in Beijing and Hebei, and VOC mitigation in Hebei. Market-based policies and incentive measures also need to be enhanced, with local governments’ expanding the development of environmentally friendly industry to upgrade industrial structure for economic growth.

Multi-sensor temporal assessment of tropospheric nitrogen dioxide column densities over Pakistan.

Spatial and temporal distributions of tropospheric NO2 vertical column densities over Pakistan during the period 2002-2014 are discussed. Data products from three satellite instruments SCIAMACHY, OMI, and GOME-2 are used to prepare a database of tropospheric NO2 column densities over Pakistan and temporal evolution is also determined. Plausible NO2 sources in Pakistan are also discussed. The results show a large NO2 growth over all provinces and the major cities of Pakistan except the megacity of Karachi. Decline in industrial activities due to energy crises, worsening law and order situation, terrorist attacks, and political instability was explored as the main factor for lower NO2 VCDs over Karachi City. The overall increase can be attributed to the anthropogenic emissions over the areas with high population, traffic density, and industrial activities. Source identification revealed that use of fossil fuels by various sectors including power generation, vehicles, and residential sectors along with agriculture fires are among significant sources of NO2 emissions in Pakistan. Existing emission inventories such as EDGARv4.2 and MACCity largely underestimate the true anthropogenic NOx emissions in Pakistan. This study may provide vital information to policy makers and regulatory authorities in developing countries, including Pakistan, in order to devise effective air pollution abatement policies.

Estimating health and economic benefits of reductions in air pollution from agriculture

Agricultural ammonia emissions strongly contribute to fine particulate air pollution (PM2.5) with significant impacts on human health, contributing to mortality. We used model calculated emission scenarios to examine the health and economic benefits accrued by reducing agricultural emissions. We applied the “value of statistical life” metric to monetize the associated health outcomes. Our analysis indicates that a 50% reduction in agricultural emissions could prevent >200 thousand deaths per year in the 59 countries included in our study, notably in Europe, Russia, Turkey, the US, Canada and China, accompanied with economic benefits of many billions US$. In the European Union (EU) mortality could be reduced by 18% with an annual economic benefit of 89 billion US$. A theoretical complete phase-out of agricultural emissions could lead to a reduction in PM2.5 related mortality of >50% plus associated economic costs in 42 out of the 59 countries studied. Within the EU, 140 thousand deaths could be prevented per year with an associated economic benefit of about 407billionUS$/year. A cost-benefit assessment of ammonia emission abatement options for the EU indicates that the reduction of agricultural emissions generates net financial and social benefits. The monetization of the health benefits of air pollution abatement policies and the costs of implementation can help devise cost-effective air quality management strategies.

Did policies to abate atmospheric emissions from traffic have a positive effect in London?

A large number of policy initiatives are being taken at the European level, across the United Kingdom and in London to improve air quality and reduce population exposure to harmful pollutants from traffic emissions. Trends in roadside increments of nitrogen oxides (NOX), nitrogen dioxide (NO2), particulate matter (PM), black carbon (CBLK) and carbon dioxide (CO2) were examined at 65 London monitoring sites for two periods of time: 2005–2009 and 2010–2014. Between 2005 and 2009 there was an overall increase in NO2 reflecting the growing evidence of real world emissions from diesel vehicles. Conversely, NO2 decreased by 10%·year−1 from 2010 onwards along with PM2.5 (−28%·year−1) and black carbon (−11%·year−1). Downwards trends in air pollutants were not fully explained by changes in traffic counts therefore traffic exhaust emission abatement policies were proved to be successful in some locations. PM10 concentrations showed no significant overall change suggesting an increase in coarse particles which offset the decrease in tailpipe emissions; this was especially the case on roads in outer London where an increase in the number of Heavy Good Vehicles (HGVs) was seen. The majority of roads with increasing NOX experienced an increase in buses and coaches. Changes in CO2 from 2010 onwards did not match the downward predictions from reduced traffic flows and improved fleet efficiency. CO2 increased along with increasing HGVs and buses. Polices to manage air pollution provided differential benefits across London's road network. To investigate this, k-means clustering technique was applied to group roads which behaved similarly in terms of trends to evaluate the effectiveness of policies to mitigate traffic emissions. This is the first time that London's roadside monitoring sites have been considered as a population rather than summarized as a mean behaviour only, allowing greater insight into the differential changes in air pollution abatement policies.

Modelling and mapping trace element accumulation in Sphagnum peatlands at the European scale using a geomatic model of pollutant emissions dispersion

Trace elements (TEs) transported by atmospheric fluxes can negatively impact isolated ecosystems. Modelling based on moss-borne TE accumulation makes tracking TE deposition in remote areas without monitoring stations possible. Using a single moss species from ombrotrophic hummock peatlands reinforces estimate quality. This study used a validated geomatic model of particulate matter dispersion to identify the origin of Cd, Zn, Pb and Cu accumulated in Sphagnum capillifolium and the distance transported from their emission sources. The residential and industrial sectors of particulate matter emissions showed the highest correlations with the TEs accumulated in S. capillifolium (0.28(Zn)-0.56(Cu)) and (0.27(Zn)-0.47(Cu), respectively). Distances of dispersion varied depending on the sector of emissions and the considered TE. The greatest transportation distances for mean emissions values were found in the industrial (10.6 km when correlating with all TEs) and roads sectors (13 km when correlating with Pb). The residential sector showed the shortest distances (3.6 km when correlating with Cu, Cd, and Zn). The model presented here is a new tool for evaluating the efficacy of air pollution abatement policies in non-monitored areas and provides high-resolution (200 × 200 m) maps of TE accumulation that make it possible to survey the potential impacts of TEs on isolated ecosystems.

A cognitive map framework to support integrated environmental assessment

In this work we present the rational and design of a methodology to support Integrated Environmental Assessment using the DPSIR (Driving Forces–Pressures–State–Impact–Response) causal-effect framework and non-monotonic Fuzzy Cognitive Maps. The methodology is based on key pillars in environmental management, namely connecting the socioeconomic and the natural environment dimensions into a policy oriented context; integration of stakeholders with inter-sectorial synergies and tradeoffs; handling of ambiguities and uncertainties intrinsic to environmental modeling and representation of complex non-linear cause-effect relationships in the form of Fuzzy Inference Systems, capable of adapting dynamically the influence between indicators. The methodology has the potential to support the development of informed policies and improves reliability through transparent, traceable and reproducible results. The illustrative example assesses the impact of air pollution abatement policies according to expert perceptions using proactive scenarios; the results revealed that, despite some positive changes, air protection activities are missing an overall strategic vision.

A methodology to estimate uncertainty for emission projections through sensitivity analysis

Air pollution abatement policies must be based on quantitative information on current and future emissions of pollutants. As emission projections uncertainties are inevitable and traditional statistical treatments of uncertainty are highly time/resources consuming, a simplified methodology for nonstatistical uncertainty estimation based on sensitivity analysis is presented in this work. The methodology was applied to the “with measures” scenario for Spain, concretely over the 12 highest emitting sectors regarding greenhouse gas and air pollutants emissions. Examples of methodology application for two important sectors (power plants, and agriculture and livestock) are shown and explained in depth. Uncertainty bands were obtained up to 2020 by modifying the driving factors of the 12 selected sectors and the methodology was tested against a recomputed emission trend in a low economic-growth perspective and official figures for 2010, showing a very good performance.Implications: A solid understanding and quantification of uncertainties related to atmospheric emission inventories and projections provide useful information for policy negotiations. However, as many of those uncertainties are irreducible, there is an interest on how they could be managed in order to derive robust policy conclusions. Taking this into account, a method developed to use sensitivity analysis as a source of information to derive nonstatistical uncertainty bands for emission projections is presented and applied to Spain. This method simplifies uncertainty assessment and allows other countries to take advantage of their sensitivity analyses.

Health benefits of air pollution abatement policy: Role of the shape of the concentration–response function

There is strong evidence that fine particulate matter (aerodynamic diameter <2.5 μm; PM2.5) air pollution contributes to increased risk of disease and death. Estimates of the burden of disease attributable to PM2.5 pollution and benefits of reducing pollution are dependent upon the shape of the concentration response (C-R) functions. Recent evidence suggests that the C-R function between PM2.5 air pollution and mortality risk may be supralinear across wide ranges of exposure. Such results imply that incremental pollution abatement efforts may yield greater benefits in relatively clean areas than in highly polluted areas. The role of the shape of the C-R function in evaluating and understanding the costs and health benefits of air pollution abatement policy is explored. There remain uncertainties regarding the shape of the C-R function, and additional efforts to more fully understand the C-R relationships between PM2.5 and adverse health effects are needed to allow for more informed and effective air pollution abatement policies. Current evidence, however, suggests that there are benefits both from reducing air pollution in the more polluted areas and from continuing to reduce air pollution in cleaner areas.Implications: Estimates of the benefits of reducing PM2.5 air pollution are highly dependent upon the shape of the PM2.5-mortality concentration-response (C-R) function. Recent evidence indicates that this C-R function may be supralinear across wide ranges of exposure, suggesting that incremental pollution abatement efforts may yield greater benefits in relatively clean areas than in highly polluted areas. This paper explores the role of the shape of the C-R function in evaluating and understanding the costs and health benefits of PM2.5 air pollution abatement.

Impacts of NMVOC emissions on human health in European countries for 2000–2010: Use of sector-specific substance profiles

Non-methane volatile organic compounds (NMVOC) are known to cause damages to human health via two main pathways, viz. the direct toxic effects exerted by certain substances (termed here human toxicity) and their indirect effects related to photochemical ozone formation (POF). To comprehensively assess the damages at national level and thus define adequate air pollution abatement policies, substance breakdowns are needed. However, these are not readily available as total NMVOC emissions are only reported at sector level. In this study, we developed a reproducible methodology that combines available speciation profiles, i.e. distributions of substances emitted per type of sources, and sectoral NMVOC information to reach country-specific, substance-specific emission profiles. Annual emission inventories, including 270 single substances and 52 unrefined groups of substances, were determined for 31 European countries within the period 2000–2010. Using life cycle impact assessment methods for POF and human toxicity, impacts on human health were quantified. The results indicated that a strong linear correlation exists between POF impacts and the total NMVOC emissions, suggesting that air pollution abatement policies could use total NMVOC emissions as a proxy for reducing these impacts. Despite underlying uncertainties, the results also demonstrated that the POF impacts from NMVOC are negligible compared to their direct toxic impacts. The analysis of the results revealed that the toxic impacts (i) are caused by few substances, such as formaldehyde, acrolein and furan, (ii) primarily stem from transportation sectors and from residential sources, and (iii) are found not to correlate with total NMVOC emissions. Our findings therefore suggest the need for supporting air pollution abatement strategies with comprehensive impact assessments, which, in addition to complementing emission- and concentration-based indicators, should allow identifying country-specific improvement potentials at substance and sector levels.

Deposition von Luftschadstoffen in der Schweiz: Entwicklung, aktueller Stand und Bewertung

Deposition of air pollutants in Switzerland: development, current situation and assessment In total, the emissions of nitrogen, sulfur and other anthropogenic air pollutants in Switzerland were reduced in the last decades. This is the result of effective measures of the air pollution abatement policies. Sulfur input in forests today is nearly negligible due to a reduction of emissions by more than 90 percent. Regarding nitrogen emissions the picture is less consistent: they are reduced in consequence of the abatement of nitrogen oxides emissions from combustion processes, but ammonia emissions from agriculture show a considerably less pronounced reduction, and since the year 2000 they remain on a high level. In 2007 the average inputs in forests amounted to 24 kg nitrogen per ha and 4.8 kg sulfur per ha. Natural nitrogen input is 1 to 3 kg per ha and year. On nearly all forest sites (&amp;gt;95%) the critical loads for nitrogen were exceeded. Nitrogen input consists of roughly two thirds of reduced ammonia nitrogen from agricultural activities and one third of oxidized nitrogen from combustion processes (traffic, households, industries, commerce). In 2007 the acidification potential of nitrogen and sulfur input in forests on many sites was considerably higher than the amount of available neutralizing cations (Ca, Mg, K) from the weathering of minerals and their input with dust. Further efforts are necessary to reduce the nitrogen load in forests to a tolerable amount.

Importance of source apportionment modeling in air pollution abatement policy

Air pollution problems, particularly in the emerging economies, are endangering the health and welfare of people. Both ambient and indoor air pollution levels have reached an alarming stage in the developing countries. Major sources of ambient air pollution are industries, power plants, and motor vehicles emitting the high levels of Oxides of Sulfur (SOx), Oxides of Nitrogen (NOx), Carbon Monoxide (CO), Suspended Particulate Matter (SPM), Hydro Carbons (HC), and numerous other pollutants. On the other hand, high level of indoor air pollution is the result of low quality fuels such as wood, coal, and kerosene, etc., that are being used in rural and urban poor households. Several studies have shown that the levels of SPM, NOx, and HC are resulting in higher incidences of respiratory diseases like tuberculosis, cardiovascular diseases, and asthma. In addition to the health hazards, air pollution also has several other detrimental effects such as reduction in visibility, spoiling of buildings, damage to material and machines, and ill effects on vegetation and animals (Hopke 1988; Okamoto et al. 1990; Sharma and Patil 1992, 1994; Sharma 2007). While the sources of the most gaseous pollutants are well defined, it is difficult to identify the origin of particulate pollutants. Even if it is possible to identify the major sources of such pollutants, qualitatively, their quantitative contributions may not be ascertained by the policy makers. As the decision makers are not sure of the share of pollution from various contributing sources in an area, they can not use any policy measure focusing on a particular source or a group of sources. Thus, implementation of a pollution abatement policy without identifying the real culprit, i.e., the major pollution source(s) in an area becomes difficult. In such a situation, the site specific source apportionment techniques could act as the management and decisionmaking tools. Source Apportionment Modeling (SAM) techniques are basically statistical methods, which essentially use a chemical mass balance equation. The main assumption of these techniques is that the pollutants do not transform, physically or chemically, during their transport from the source to the receptor. For example, the amount of total lead (Pb) arriving at a receptor will be the linear sum of the lead emitted by all sources of lead surrounding the receptor, say, lead from automobiles, lead from an incinerator, etc.,

Spatial aspects affecting acidification factors in European acidification modelling

Plain linear models have recently been used in methodologies to model fate and transport for assessing acidification in life cycle impact assessment (LCIA), or in support of air pollution abatement policies. These models originate from a statistical analysis of the relationship between inputs and outputs of physically-based models that reflect the mechanics of a system in detail. Linear models applied to assess acidification use an acidification factor ( AF), which relates changes in the magnitude of emissions to changes in the total area that is protected against acidification in Europe. The changes in emission volume refer to changes of one substance, within one country and one sector or one grid cell. This paper evaluates the dependence of AFs on three spatial characteristics, i.e. the spatial emission and deposition resolution, the spatial emission distribution and the actual spatial location of emissions. The applied spatial resolutions of emission and deposition cause non-systematic variations in AFs of up to 60%, relative to the finest resolution. The manner in which the distribution of emissions is modelled, i.e. grid or sector-specific, is shown to affect AFs considerably, as well. We conclude that spatial characteristics of the physically-based acidification model can affect the assessment of acidification by means of plain linear models.