Source-receptor Model Research Articles

PSCF method for source identification of particulate matter in an agricultural background region in Brazil

ABSTRACT The use of mathematical and statistical models to investigate potential sources of pollutants that have been transported by air masses to a study site is important for establishing control and monitoring measures for air pollutants such as PM10 and PM2.5. During the study period, from 2018 to 2021, the concentrations of PM10 and PM2.5 recorded in Ribeirão Preto (SP, Brazil) were higher during spring and winter, with a tendency to increase the amplitude and its maximum values relative to daily averages. The source-receptor model, Potential Source Contribution Function (PSCF), was used to identify probable sources of these pollutants, and the regions known as Triângulo Mineiro and Intermediate Geographic Region of Juiz de Fora (MG, Brazil) were the main regions associated with high PSCF probability values (> 0.5) as sources of PM. These regions indicate that the possible sources of PM emissions are associated with industrial complexes and agriculture, especially coffee production.

A source apportionment and air quality planning methodology for NO2 pollution from traffic and other sources

In view of upcoming more stringent air quality limits and the ambition to align with the WHO guidelines, nitrogen dioxide (NO2) pollution from traffic and other sources will remain a problem in the EU. To assess the impact of traffic measures and emission reductions in other sectors on NO2-concentrations, an EU-wide high-resolution NO2 source apportionment web-application was developed. The application allows users to define scenarios in a user-friendly way and quickly visualize the NO2-concentrations at measurement stations and in cities. The user can configure a new Euro 7/VII emission standard and additionally define urban access regulations scenarios in cities. To capture the spatial scales of NO2 pollution, the SHERPA source-receptor model was used in combination with the QUARK kernel dispersion model. The first model considers long-distance impacts, the latter considers the strong concentration gradients close to roads. This paper focuses on the methodology, a follow-up paper describes the web-application.

Source apportionment of volatile organic compounds during paddy-residue burning season in north-west India reveals large pool of photochemically formed air toxics

Paddy-residue burning is associated with poor air quality in north-west India during October–November every year. However, till date a quantitative study of its contribution to ambient volatile organic compounds (VOCs) using highly time-resolved measurements within the region has been lacking. Several VOCs like benzene are carcinogenic and also fuel formation of secondary pollutants such as secondary organic aerosol (SOA) and ozone. Here, we undertake quantitative source-apportionment using a PMF source-receptor model on a high-quality in-situ measured dataset of 54 VOCs in Punjab, India, and validate the model results using source profiles. The contribution of the seven most dominant sources to the total VOC mass concentrations were: daytime photochemistry and biogenic VOCs (BVOCs) (26%), followed by solid-fuel usage and waste-disposal (18%), traffic (two-wheeler 14% and four-wheeler 10%), photochemically aged biomass burning (17%), industries and solvent usage (9%), and fresh paddy residue burning (6%). Ozone production potential was dominated by solid fuel usage and waste disposal (25%), followed by traffic (two-wheeler 11% and four-wheeler 12%), BVOCs and photooxidation products (21%), photochemically aged biomass burning (16%), industries & solvent usage (9%) and fresh paddy residue burning (6%). SOA production was dominated by traffic (two-wheeler 26% and four-wheeler 28%) followed by solid fuel usage and waste disposal (22%), photochemically aged biomass burning emissions (15%) with minor contribution from industries & solvents (6%), fresh paddy residue burning (2%) and photochemistry and biogenic VOCs (1%). Comparisons with global emission inventories REASv3.2.1 and EDGARv4.3.2, showed both overestimate the industry and solvent source. Further, EDGARv4.3.2 underestimated the traffic source whereas paddy residue burning emissions are absent in REASv3.2.1. Although the overall mass contribution of paddy-residue burning emissions isn't high, our results show that health-relevant compounds emitted directly and formed photochemically from biomass burning sources active at this time are majorly responsible for the unhealthy air.

Source apportionment of PM2.5 oxidative potential in an East Mediterranean site

This study aimed to evaluate the oxidative potential (OP) of PM2.5 collected for almost a year in an urban area of the East Mediterranean. Two acellular assays, based on ascorbic acid (AA) and dithiothreitol (DTT) depletion, were used to measure the OP. The results showed that the mean volume normalized OP-AAv value was 0.64 ± 0.29 nmol·min−1·m−3 and the mean OP-DTTv was 0.49 ± 0.26 nmol·min−1·m−3. Several approaches were adopted in this work to study the relationship between the species in PM2.5 (carbonaceous matter, water-soluble ions, major and trace elements, and organic compounds) or their sources and OP values. Spearman correlations revealed strong correlations of OP-AAv with carbonaceous subfractions as well as organic compounds while OP-DTTv seemed to be more correlated with elements emitted from different anthropogenic activities. Furthermore, a multiple linear regression method was used to estimate the contribution of PM2.5 sources, determined by a source-receptor model (Positive Matrix Factorization), to the OP values. The results showed that the sources that highly contribute to the PM2.5 mass (crustal dust and ammonium sulfate) were not the major sources contributing to the values of OP. Instead, 69 % of OP-AAv and 62 % of OP-DTTv values were explained by three local anthropogenic sources: Heavy Fuel Oil (HFO) combustion from a power plant, biomass burning, and road traffic emissions. As for the seasonal variations, higher OP-AAv values were observed during winter compared to summer, while OP-DTTv did not show any significant differences between the two seasons. The contribution of biomass burning during winter was 33 and 34 times higher compared to summer for OP-AAv and OP-DTTv, respectively. On the other hand, higher contributions were observed for HFO combustion during summer.

Spatial and PMF analysis of particle size distributions simultaneously measured at four locations at the roadside of highways

In urban areas, particulate matter emitted from vehicles directly affects the health of citizens near roads. Thus, in this study, particle size distribution was measured by the horizontal and vertical distances along a highway road with heavy traffic to characterize the dispersion phenomena of particulate matter emitted from vehicles. In addition, the contribution of pollution sources was analyzed using a source-receptor model. A concentration gradient was observed in which the concentration decreased with the increase in the distance from the road when the wind blew from the road to the monitoring locations. The concentration was slightly higher within 50 m of the road when the wind blows parallel to the road, and similar concentrations were found at the other monitoring locations further away from the roads. In particular, the higher the turbulence intensity of the wind, the lower is the concentration gradient coefficient because of the more enhanced mixing and dispersion. A positive matrix factorization (PMF) model with the measured particle size distribution data in the range of 9–300 nm resulted in a contribution of about 70 % (number) and 20 % (mass) to particle concentrations because of six types of vehicles including LPG, two gasoline vehicles (GDI, MPI), and three diesel vehicles with 3rd, 4th, and 5th emission classes. It showed a decrease in the vehicular contribution as the distance from the road increased. Particle number concentrations decreased with increasing altitude up to 30 m above the ground. The results of this study can be useful in deriving generalized gradient equations of particle concentrations exposed by distance and wind direction at the roadside using traffic and meteorological conditions and for establishing environmental policies, such as roadside exposure assessment, in the future. A capsule abstractDispersion of particles emitted from vehicles on a busy highway was characterized by roadside measurements of horizontal and vertical profiles of particle size distributions measured at four locations. The source profiles and contributions were estimated by major sources using a source-receptor model such as PMF.

How Valuable Are Small Measurement Datasets in Supplementing Occupational Exposure Models? A Numerical Study Using the Advanced Reach Tool

The Advanced REACH Tool (ART) is the most detailed exposure model currently available for estimating inhalation exposures to dusts, vapours, and aerosols under a broad range of exposure scenarios. The ART follows a Bayesian approach, making use of a calibrated source-receptor model to provide central estimates of exposures and information on exposure variability from meta-analyses in the literature. Uniquely amongst exposure models, the ART provides a facility to update the baseline estimates from the mechanistic model and variance components using measurement data collected on the exposure scenario; however, in practical use, this facility is little used. In this paper, the full capability of the ART tool is demonstrated using a small number of carefully chosen case studies that each had a sufficient breadth of personal exposure measurement data to support a measurement-led exposure assessment. In total, six cases studies are documented, three where the estimate from the source-receptor model of the ART was consistent with measurement data, and a further three case studies where the source-receptor model of the ART was inconsistent with measurement data, resulting in a prior-data conflict. A simulation study was designed that involved drawing subsets of between two and ten measurements from the available measurement dataset, with estimates of the geometric mean (GM) and 90th percentile of exposures from the posterior distribution of ART compared against measurement-based estimates of these summaries. Results from this work indicate that very substantial reductions in the uncertainty associated with estimates of the GM and 90th percentile could be achieved with as few as two measurements, with results in detail sensitive to both the measurements themselves and worker and company labels associated with the measurements. For case studies involving prior-data conflicts, the estimates of the GM and 90th percentile rapidly changed as measurement data were used to update the prior. However, results suggest that the current statistical model of the ART does not allow a complete resolution of a prior-data conflict.

What role for asbestos in idiopathic pulmonary fibrosis? Findings from the IPF job exposures case–control study

BackgroundAsbestos has been hypothesised as the cause of the recent global increase in the incidence of ‘idiopathic’ pulmonary fibrosis (IPF). Establishing this has important diagnostic and therapeutic implications. The association...

Assessment of sources and health impacts of PM10 in an urban environment over eastern coastal plain of India

Aerosol health impacts are gaining considerable attention from the scientific community. Our study's primary purpose was to identify the source regions of PM10 and quantify its long-term health effects at an eastern Indian urban site Bhubaneswar from July 2018 to June 2019. The seasonal average of PM10 surface observations displayed higher values in winter, followed by post-monsoon, summer and monsoon. Eastern India, Northern India, and South-East Asia emerged as potential source regions of PM10 contributors to the study location using source-receptor models. The health endpoints, (i) incidence of chronic bronchitis in adults, (ii) post neonatal infant mortality and, (iii) prevalence of bronchitis in children, were estimated employing the World Health Organization developed model, AirQ+. The attributable proportion, the excess number of attributable cases, and the excess number of attributable cases per 100,000 population for three endpoints showed the highest impact during the winter season. Winter impact is 3 to 5 times higher compared to the rest of other seasons. This study highlights the health impact of PM10 on the population of Bhubaneswar, especially during winter. Thus, it is imperative to give considerable focus to controlling and mitigating air pollution at the investigation location.

High-resolution modeling of the distribution of surface air pollutants and their intercontinental transport by a global tropospheric atmospheric chemistry source–receptor model (GNAQPMS-SM)

Abstract. Many efforts have been devoted to quantifying the impact of intercontinental transport on global air quality by using global chemical transport models with horizontal resolutions of hundreds of kilometers in recent decades. In this study, a global online air quality source–receptor model (GNAQPMS-SM) is designed to effectively compute the contributions of various regions to ambient pollutant concentrations. The newly developed model is able to quantify source–receptor (S-R) relationships in one simulation without introducing errors by nonlinear chemistry. We calculate the surface and planetary boundary layer (PBL) S-R relationships in 19 regions over the whole globe for ozone (O3), black carbon (BC), and non-sea-salt sulfate (nss-sulfate) by conducting a high-resolution (0.5∘ × 0.5∘) simulation for the year 2018. The model exhibits a realistic capacity in reproducing the spatial distributions and seasonal variations of tropospheric O3, carbon monoxide, and aerosols at global and regional scales – Europe (EUR), North America (NAM), and East Asia (EA). The correlation coefficient (R) and normalized mean bias (NMB) for seasonal O3 at global background and urban–rural sites ranged from 0.49 to 0.87 and −2 % to 14.97 %, respectively. For aerosols, the R and NMB in EUR, NAM, and EA mostly exceed 0.6 and are within ±15 %. These statistical parameters based on this global simulation can match those of regional models in key regions. The simulated tropospheric nitrogen dioxide and aerosol optical depths are generally in agreement with satellite observations. The model overestimates ozone concentrations in the upper troposphere and stratosphere in the tropics, midlatitude, and polar regions of the Southern Hemisphere due to the use of a simplified stratospheric ozone scheme and/or biases in estimated stratosphere–troposphere exchange dynamics. We find that surface O3 can travel a long distance and contributes a non-negligible fraction to downwind regions. Non-local source transport explains approximately 35 %–60 % of surface O3 in EA, South Asia (SAS), EUR, and NAM. The O3 exported from EUR can also be transported across the Arctic Ocean to the North Pacific and contributes nearly 5 %–7.5 % to the North Pacific. BC is directly linked to local emissions, and each BC source region mainly contributes to itself and surrounding regions. For nss-sulfate, contributions of long-range transport account for 15 %–30 % within the PBL in EA, SAS, EUR, and NAM. Our estimated international transport of BC and nss-sulfate is lower than that from the Hemispheric Transport of Air Pollution (HTAP) assessment report in 2010, but most surface O3 results are within the range. This difference may be related to the different simulation years, emission inventories, vertical and horizontal resolutions, and S-R revealing methods. Additional emission sensitivity simulation shows a negative O3 response in receptor region EA in January from EA. The difference between two methods in estimated S-R relationships of nss-sulfate and O3 are mainly due to ignoring the nonlinearity of pollutants during chemical processes. The S-R relationship of aerosols within EA subcontinent is also assessed. The model that we developed creates a link between the scientific community and policymakers. Finally, the results are discussed in the context of future model development and analysis opportunities.

Climate and air pollution implications of potential energy infrastructure and policy measures in India

India is a rapidly developing economy with interrelated air quality, sustainable development, and climate change mitigation goals. There are unique challenges to achieving each of these goals as well as potential tradeoffs among them. This study examines the implications of possible future energy, climate, and air pollution control policies and measures in India through 2050. We take a scenario approach using the GCAM global energy-climate-land model combined with the Hector simple climate model and the TM5-FASST air quality source-receptor model to examine energy, climate and air quality outcomes. Reducing use of traditional biomass in buildings can reduce primary carbonaceous particulate emissions well below 2015 levels. However, policies that are more ambitious than current plans would likely be required to reduce SO2 and NOx emissions well below 2015 levels. Among single policy cases considered, pricing of greenhouse gas (GHG) emissions and expansion of natural gas infrastructure have the largest impacts on overall energy system changes relative to the reference scenario. Ambitious air pollution control and GHG policies lead to the largest reductions in air pollution concentrations and radiative forcing, respectively. However, ambitious air pollution control and GHG policies differ in the extent to which they support or impede other policy objectives. Forcing increases due to reduced aerosols from ambitious air pollution policies can be mitigated, at least in part, by applying air pollution control and GHG policies together.

Trends, composition, and sources of carbonaceous aerosol at the Birkenes Observatory, northern Europe, 2001–2018

Abstract. We present 18 years (2001–2018) of aerosol measurements, including organic and elemental carbon (OC and EC), organic tracers (levoglucosan, arabitol, mannitol, trehalose, glucose, and 2-methyltetrols), trace elements, and ions, at the Birkenes Observatory (southern Norway) – a site representative of the northern European region. The OC/EC (2001–2018) and the levoglucosan (2008–2018) time series are the longest in Europe, with OC/EC available for the PM10, PM2.5 (fine), and PM10–2.5 (coarse) size fractions, providing the opportunity for a nearly 2-decade-long assessment. Using positive matrix factorization (PMF), we identify seven carbonaceous aerosol sources at Birkenes: mineral-dust-dominated aerosol (MIN), traffic/industry-like aerosol (TRA/IND), short-range-transported biogenic secondary organic aerosol (BSOASRT), primary biological aerosol particles (PBAP), biomass burning aerosol (BB), ammonium-nitrate-dominated aerosol (NH4NO3), and (one low carbon fraction) sea salt aerosol (SS). We observed significant (p<0.05), large decreases in EC in PM10 (−3.9 % yr−1) and PM2.5 (−4.2 % yr−1) and a smaller decline in levoglucosan (−2.8 % yr−1), suggesting that OC/EC from traffic and industry is decreasing, whereas the abatement of OC/EC from biomass burning has been slightly less successful. EC abatement with respect to anthropogenic sources is further supported by decreasing EC fractions in PM2.5 (−3.9 % yr−1) and PM10 (−4.5 % yr−1). PMF apportioned 72 % of EC to fossil fuel sources; this was further supported by PMF applied to absorption photometer data, which yielded a two-factor solution with a low aerosol Ångstrøm exponent (AAE = 0.93) fraction, assumed to be equivalent black carbon from fossil fuel combustion (eBCFF), contributing 78 % to eBC mass. The higher AAE fraction (AAE = 2.04) is likely eBC from BB (eBCBB). Source–receptor model calculations (FLEXPART) showed that continental Europe and western Russia were the main source regions of both elevated eBCBB and eBCFF. Dominating biogenic sources explain why there was no downward trend for OC. A relative increase in the OC fraction in PM2.5 (+3.2 % yr−1) and PM10 (+2.4 % yr−1) underscores the importance of biogenic sources at Birkenes (BSOA and PBAP), which were higher in the vegetative season and dominated both fine (53 %) and coarse (78 %) OC. Furthermore, 77 %–91 % of OC in PM2.5, PM10–2.5, and PM10 was attributed to biogenic sources in summer vs. 22 %–37 % in winter. The coarse fraction had the highest share of biogenic sources regardless of season and was dominated by PBAP, except in winter. Our results show a shift in the aerosol composition at Birkenes and, thus, also in the relative source contributions. The need for diverse offline and online carbonaceous aerosol speciation to understand carbonaceous aerosol sources, including their seasonal, annual, and long-term variability, has been demonstrated.

Atmospheric Biodetection Part I: Study of Airborne Bacterial Concentrations from January 2018 to May 2020 at Saclay, France.

Background: The monitoring of bioaerosol concentrations in the air is a relevant endeavor due to potential health risks associated with exposure to such particles and in the understanding of their role in climate. In this context, the atmospheric concentrations of bacteria were measured from January 2018 to May 2020 at Saclay, France. The aim of the study was to understand the seasonality, the daily variability, and to identify the geographical origin of airborne bacteria. Methods: 880 samples were collected daily on polycarbonate filters, extracted with purified water, and analyzed using the cultivable method and flow cytometry. A source receptor model was used to identify the origin of bacteria. Results: A tri-modal seasonality was identified with the highest concentrations early in spring and over the summer season with the lowest during the winter season. Extreme changes occurred daily due to rapid changes in meteorological conditions and shifts from clean air masses to polluted ones. Conclusion: Our work points toward bacterial concentrations originating from specific seasonal-geographical ecosystems. During pollution events, bacteria appear to rise from dense urban areas or are transported long distances from their sources. This key finding should drive future actions to better control the dispersion of potential pathogens in the air, like persistent microorganisms originating from contaminated areas.

Primary Sources of Polycyclic Aromatic Hydrocarbons to Streambed Sediment in Great Lakes Tributaries Using Multiple Lines of Evidence.

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread and potentially toxic contaminants in Great Lakes (USA/Canada) tributaries. The sources of PAHs are numerous and diverse, and identifying the primary source(s) can be difficult. The present study used multiple lines of evidence to determine the likely sources of PAHs to surficial streambed sediments at 71 locations across 26 Great Lakes Basin watersheds. Profile correlations, principal component analysis, positive matrix factorization source‐receptor modeling, and mass fractions analysis were used to identify potential PAH sources, and land‐use analysis was used to relate streambed sediment PAH concentrations to different land uses. Based on the common conclusion of these analyses, coal‐tar–sealed pavement was the most likely source of PAHs to the majority of the locations sampled. The potential PAH‐related toxicity of streambed sediments to aquatic organisms was assessed by comparison of concentrations with sediment quality guidelines. The sum concentration of 16 US Environmental Protection Agency priority pollutant PAHs was 7.4–196 000 µg/kg, and the median was 2600 µg/kg. The threshold effect concentration was exceeded at 62% of sampling locations, and the probable effect concentration or the equilibrium partitioning sediment benchmark was exceeded at 41% of sampling locations. These results have important implications for watershed managers tasked with protecting and remediating aquatic habitats in the Great Lakes Basin. Environ Toxicol Chem 2020;39:1392–1408. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Atmospheric polychlorinated biphenyls from an urban site near informal electronic waste recycling area and a suburban site of Chennai city, India

Recent studies evidenced informal electronic waste (e-waste) recycling as a potential source of polychlorinated biphenyls (PCBs) in the metropolitan environment of India. Given the recent evidences on the release of hazardous organic compounds from the informal e-waste recycling workshops in the Chennai city, we have conducted high volume air sampling in an urban site close to the informal e-waste recycling corridor and in a suburban site located about 35 km away from the urban center. Weekly diurnal gaseous and particulate phase samples were collected from both urban and suburban sites during summer and winter samples were collected only from suburban site. Mean atmospheric PCB levels in the urban site (Avg ± Stdev, 46 ± 16 ng/m3) is several orders of magnitude higher than suburban summer (10 ± 12 ng/m3) and winter (4 ± 3 ng/m3). Back trajectories originating from the land seems to have impacted the samples recorded with maximum PCB concentration. No significant difference was seen between summer and winter atmospheric PCBs in the suburban site. In urban site, PCB-52 and dioxin like PCBs (dl-PCBs) have increased from the past observations with maximum PCB-52 concentration in night time samples. Positive matrix factorization source-receptor model outputs suggest that in the urban centers, open burning in municipal dumpsites is a major source for PCB-52, while dl-PCBs were related to e-waste recycling by the informal sector. Exponential increment in most toxic non-ortho dl-PCBs proclaims the severity of on-going sources which contributed to the high toxic equivalency (TEQs) upto 105 pg TEQ/m3.

Variability and Geographical Origin of Five Years Airborne Fungal Spore Concentrations Measured at Saclay, France from 2014 to 2018

Airborne fungal spores (AFS) represent the major fraction of primary biological aerosol particles (PBAPs), and they are studied worldwide largely due to their important role within the Earth system. They have an impact on climate and human health, and they contribute to the propagation of diseases. As their presence in the air depends largely on studied ecosystems, a spore trap was used to monitor their atmospheric concentrations from 2014 to December 2018 in Saclay, a suburban area in the megacity of Paris. The main objective of this work was: (1) to understand the atmospheric variability of AFS in relation to different variables such as meteorological factors, agricultural practice, and (2) to identify their geographical origin by using a source receptor model. During our period of observation, 30 taxa have been identified under a light microscope. In order of importance, Ascospores, Cladosporium, Basidiospores, Tilletiopsis, Alternaria were found to be the most abundant types respectively (50.8%, 33.6%, 7.6%, 1.8%, and 1.3%) accounting for 95% of the atmospheric concentrations. We observed a general decrease associated with a strong interannual variability. A bimodal seasonal cycle was identified with a first maximum in July and a second in October. The main parameters driving the atmospheric concentration are temperature and precipitation. The daily variability is strongly activated by successive periods of hot weather and rainfall, multiplying the concentration by a factor of 1000 in less than 12 hours. Results from the source receptor model ZeFir point out unambiguous different origins of AFS due to specific sources impacting the observation site. Our study also indicated that a hydrological stress has a direct effect on the daily concentrations. This last point should be taken into account for every stressed ecosystem studied in a global warming context. This is particularly important for Mediterranean areas where water is a key control of the growth and dispersion of fungal spores.

The Ruthenium-106 plume over Europe in 2017: a source-receptor model to estimate the source region

Between the end of September and the beginning of October 2017, low but detectable air concentrations of Ruthenium-106 (R106u) were measured throughout the European atmosphere. To date, the source has not been clearly identified. This study aims at constraining the location of the most likely emission source, by combining HYSPLIT back trajectories and a multi-site source-receptor model. The model follows a concentration weighted trajectory (CWT) approach, based on a R106u measurement dataset gathered by the International Atomic Energy Agency (IAEA) shortly after the event and shared by the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN). The back trajectories are computed using Global Data Assimilation System (GDAS) and ERA-Interim meteorological data, with horizontal resolution from 1.5° to 0.5°. The effect of the starting altitude was also investigated. The source-receptor model results show that the most likely emission source region extends from Ukraine to the West to the Russian Volga and Ural regions to the East, in accordance with two previous studies. The analyses also show that the identified source region is relatively insensitive to the type of meteorological data, their horizontal resolution and values of starting altitude. The model precision is found to increase with increasing number of receptors. The method is fully open-source, requires low computational resources and is therefore suited to estimate the source origin of radioactive pollutants on a real time basis, providing an additional tool to more sophisticated atmospheric models.

Contribution and uncertainty of sectorial and regional emissions to regional and global PM<sub>2.5</sub> health impacts

Abstract. In this work we couple the HTAP_v2.2 global air pollutant emission inventory with the global source receptor model TM5-FASST to evaluate the relative contributions of the major anthropogenic emission sources (power generation, industry, ground transport, residential, agriculture and international shipping) to air quality and human health in 2010. We focus on particulate matter (PM) concentrations because of the relative importance of PM2.5 emissions in populated areas and the well-documented cumulative negative effects on human health. We estimate that in 2010, depending on the region, annual averaged anthropogenic PM2.5 concentrations varied between ca. 1 and 40 µg m−3, with the highest concentrations observed in China and India, and lower concentrations in Europe and North America. The relative contribution of anthropogenic emission sources to PM2.5 concentrations varies between the regions. European PM pollution is mainly influenced by the agricultural and residential sectors, while the major contributing sectors to PM pollution in Asia and the emerging economies are the power generation, industrial and residential sectors. We also evaluate the emission sectors and emission regions in which pollution reduction measures would lead to the largest improvement on the overall air quality. We show that air quality improvements would require regional policies, in addition to local- and urban-scale measures, due to the transboundary features of PM pollution. We investigate emission inventory uncertainties and their propagation to PM2.5 concentrations, in order to identify the most effective strategies to be implemented at sector and regional level to improve emission inventories, knowledge and air quality modelling. We show that the uncertainty of PM concentrations depends not only on the uncertainty of local emission inventories, but also on that of the surrounding regions. Countries with high emission uncertainties are often impacted by the uncertainty of pollution coming from surrounding regions, highlighting the need for effective efforts in improving emissions not only within a region but also from extra-regional sources. Finally, we propagate emission inventory uncertainty to PM concentrations and health impacts. We estimate 2.1 million premature deaths per year with an uncertainty of more than 1 million premature deaths per year due to the uncertainty associated only with the emissions.

Dermal Advanced REACH Tool (dART)-Development of a Dermal Exposure Model for Low-Volatile Liquids.

This article describes the development of a mechanistic model for underpinning the dermal Advanced REACH Tool (dART), an extension of the existing ART model and its software platform. It was developed for hand exposure to low volatile liquids (vapour pressure ≤ 10 Pa at 20°C) including solids-in-liquid products. The model is based on an existing conceptual dermal source-receptor model that has been integrated into the ART framework. A structured taxonomy of workplace activities referred to as activity classes are adopted from ART. Three key processes involved in mass transport associated with dermal exposure are applied, i.e. deposition, direct emission and contact, and transfer. For deposition, the model adopts all the relevant modifying factors (MFs) applied in ART. In terms of direct emission and contact (e.g. splashes) and transfer (e.g. hand-surface contacts), the model defines independent principal MFs, i.e. substance-related factors, activity-related factors, localized- and dispersion control and exposed surface area of the hands. To address event-based exposures as much as possible, the model includes crucial events during an activity (e.g. hand immersions) and translates objective information on tools and equipment (manual or automated) to probable events (e.g. splashes) and worker behaviours (e.g. surface contacts). Based on an extensive review of peer-reviewed literature and unpublished field studies, multipliers were assigned to each determinant and provide an approximated (dimensionless) numerical value. In the absence of (sufficient) evidence, multipliers were assigned to determinants based on assumptions made during discussions by experts in the consortium. A worked example is presented to illustrate the calculation of hand exposure for a specific scenario. The dART model is not yet implemented in the ART software platform, and a robust validation of the model is necessary to determine its predictive ability. With advancing knowledge on dermal exposure and its determinants, this model will require periodic updates and refinements, in addition to further expansion of the applicability domain of the model.

TM5-FASST: a global atmospheric source–receptor model for rapid impact analysis of emission changes on air quality and short-lived climate pollutants

Abstract. This paper describes, documents, and validates the TM5-FAst Scenario Screening Tool (TM5-FASST), a global reduced-form air quality source–receptor model that has been designed to compute ambient pollutant concentrations as well as a broad range of pollutant-related impacts on human health, agricultural crop production, and short-lived pollutant climate metrics, taking as input annual pollutant emission data aggregated at the national or regional level. The TM5-FASST tool, providing a trade-off between accuracy and applicability, is based on linearized emission-concentration sensitivities derived with the full chemistry-transport model TM5. The tool has been extensively applied in various recent critical studies. Although informal and fragmented validation has already been performed in various publications, this paper provides a comprehensive documentation of all components of the model and a validation against the full TM5 model. We find that the simplifications introduced in order to generate immediate results from emission scenarios do not compromise the validity of the output and as such TM5-FASST is proven to be a useful tool in science-policy analysis. Furthermore, it constitutes a suitable architecture for implementing the ensemble of source–receptor relations obtained in the frame of the HTAP modelling exercises, thus creating a link between the scientific community and policy-oriented users.

The effects of intercontinental emission sources on European air pollution levels

Abstract. This study is based on model results from TF HTAP (Task Force on Hemispheric Transport of Air Pollution) phase II, in which a set of source receptor model experiments have been defined, reducing global (and regional) anthropogenic emissions by 20 % in different source regions throughout the globe, with the main focus on the year 2010. All the participating models use the same set of anthropogenic emissions. Comparisons of model results to measurements are shown for selected European surface sites and for ozone sondes, but the main focus here is on the contributions to European ozone levels from different world regions, and how and why these contributions differ depending on the model. We investigate the origins by use of a novel stepwise approach, combining simple tracer calculations and calculations of CO and O3. To highlight the differences, we analyse the vertical transects of the midlatitude effects from the 20 % emission reductions.The spread in the model results increases from the simple CO tracer to CO and then to ozone as the complexity of the physical and chemical processes involved increase. As a result of non-linear ozone chemistry, the contributions from non-European relative to European sources are larger for ozone compared to the CO and the CO tracer. For annually averaged ozone the contributions from the rest of the world is larger than the effects from European emissions alone, with the largest contributions from North America and eastern Asia. There are also considerable contributions from other nearby regions to the east and from international shipping. The calculated contributions to European annual average ozone from other major source regions relative to all contributions from all major sources (RAIR – Relative Annual Intercontinental Response) have increased from 43 % in HTAP1 to 82 % in HTAP2. This increase is mainly caused by a better definition of Europe, with increased emissions outside of Europe relative to those in Europe, and by including a nearby non-European source for external-to-Europe regions. European contributions to ozone metrics reflecting human health and ecosystem damage, which mostly accumulated in the summer months, are larger than for annual ozone. Whereas ozone from European sources peaks in the summer months, the largest contributions from non-European sources are mostly calculated for the spring months, when ozone production over the polluted continents starts to increase, while at the same time the lifetime of ozone in the free troposphere is relatively long. At the surface, contributions from non-European sources are of similar magnitude for all European subregions considered, defined as TF HTAP receptor regions (north-western, south-western, eastern and south-eastern Europe).