This study presents results from an Intensive Measurement Period (IMP2022) conducted during the European heatwave of July 2022, focusing on ozone, volatile organic compounds (VOCs), and carbonaceous aerosols at 31 sites across Europe. The episode featured persistent high-pressure systems, record-breaking temperatures, widespread ozone exceedances and concurrent atmospheric new particle formation and growth events. Coordinated measurements and chemistry transport modelling were used to examine the spatial variability of ozone, VOC composition, and secondary organic aerosol (SOA) formation under extreme meteorological conditions. Oxygenated VOCs (O-VOCs) constituted the largest fraction of total measured VOC mixing ratios, followed by non-methane hydrocarbons (NMHCs) and aromatics, with contributions from both anthropogenic and biogenic sources. Sensitivity simulations indicate that ozone formation was predominantly NOx-limited across most regions during IMP2022. However, the highest ozone peaks occurred under conditions of elevated NOx in combination with enhanced BVOC emissions. In contrast, SOA formation was slightly enhanced under low-NOx conditions and reduced in elevated NOx. Isoprene, aliphatic NMHCs, and O-VOCs dominated the ozone formation potential, while aromatics and monoterpenes were major contributors to SOA potential. Model simulations indicated that higher NOx concentrations can reduce SOA formation by about 10 %. The campaign also highlighted observational gaps underscoring the need for broader and higher-resolution VOC monitoring across Europe. Overall, further reductions in NOx emissions, alongside targeted control of key anthropogenic VOCs, would benefit air quality under future climate extremes.

Abstract. At the atmospheric monitoring station Schauinsland (Black Forest, Germany), high-precision long-term measurements of atmospheric CO2 and CH4 have been conducted since 1972 and 1991, respectively. An additional air intake at 35 m a.g.l. (above ground level) has been installed alongside the existing intake at 12 m a.g.l in September 2021. To ensure consistency and continuity of the historic CO2 and CH4 time series, a three-year comparison between the two intake heights has been carried out. This revealed systematic differences in CO2 mole fractions between the two levels: During summer daytime diurnal mean CO2 mole fractions at 35 m are up to 0.5 ppm higher, while night-time values are up to 1.1 ppm lower, compared to 12 m, resulting in smaller diurnal amplitudes at 35 m. Seasonal mean CO2 mole fractions are lowered by up to 0.36 ppm at 35 m relative to 12 m in summer, whereas no significant differences are observed in winter. The diurnal and seasonal mean CH4 mole fraction differences between the two intake heights are negligible. However, highly frequent CH4 spikes originating from nearby grazing cows, which are present only during the summer months, increase hourly mean mole fractions at 12 m by up to 38 ppb, while no significant influence is measured at 35 m. The REBS (Robust Extraction of the Baseline Signal) algorithm is applied to the minutely CH4 summer data at 12 m and proved to be an effective approach for identification of data affected by very local influences.

The Schneefernerhaus observatory at Zugspitze, Germany is located at 2650 m a.s.l and provides the opportunity to monitor long-range transport of air pollutants in the free troposphere. In this study, we present aerosol observations performed from July to October 2025, with special focus on aerosol light absorption, i.e. brown and black carbon. Light-absorbing carbonaceous matter (LAC) is relevant to the climate due to its short atmospheric lifetime and the dynamic behaviour of its optical properties, which change upon aging. Black carbon is included as a metric to be measured in the recent modification of the European Air Quality Directive, underscoring the need for an SI-traceable calibration chain for black carbon. This need is particularly pressing for absorption photometers (e.g., aethalometers), which are widely deployed in air quality monitoring networks. A field calibration has proven challenging given that there is no standard reference material available and that primary measurement methods are not yet ready for straightforward field deployment.In this study, we have used an Aethalometer AE36s (Aerosol d.o.o., Ljubljana, Slovenia) and a photo-acoustic extinctiometer (PAX, Droplet Measurement Technology, Longmont, USA) to monitor aerosol light absorption during a 10-week field campaign at Schneefernerhaus. Additionally, we have used particle number size distribution (PNSD), and multi-angle absorption photometer (MAAP) data to assess different aerosol physical properties. The primary objective was to use the PAX measurements as a transfer standard to calibrate AE36s measurements in the field. The calibration transfer has proven feasible for the IR wavelength of 880 nm, which is of special interest when the focus is to determine black carbon with the less interference from other LAC components.Observations in August 2025 show clearly a spike of LAC concentration with different wavelength dependencies (see Fig. 1), indicating a highly variable contribution of brown carbon to the total aerosol mass. HYSPLIT back-trajectory analysis indicate that these aerosol episodes originated from Canadian wildfires, which were highly active during the measurement period.Overall, the field calibration method using PAX as a transfer standard has proven to be reliable and plausible. However, the method is constrained by the sensitivity and limit of detection of the PAX and also require that the PAX itself is calibrated against a primary method, such as extinction-minus-scattering or photo-thermal interferometry. The development of a robust primary calibration strategy for photo-acoustic spectrometers would significantly improve the traceability chain and would minimize uncertainties for in-field calibration of absorption photometers.Figure 1. Aerosol absorption coefficient measured by an Aethalometer AE36s at Schneefernerhaus Zugspitze, Germany in August 2025.

Within the framework of multiple international conventions, Germany like other state parties is committed to monitor the air quality in the atmospheric background. Therefore, atmospheric measurements are realized by the German Environment Agency (Umweltbundesamt - UBA) with its network of 7 remote measurement stations throughout the rural background of Germany. These stations are operated by personnel and contribute data on pollutant deposition and transboundary long-range transport to the following monitoring programs: Global Atmosphere Watch (GAW), European Monitoring and Evaluation Program (EMEP), Convention on the Protection of the Marine Environment of the Baltic Sea Area (HELCOM), Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) and as well as to the EU commission within the directive on ambient air quality and cleaner air for Europe (2008/50/EC). Some pollutants are measured continuously since the late 1960s, while other pollutants especially metals and semi-metals are monitored since the early 1990s. Organic pollutants such as PAHs and POPs are regularly monitored as well starting in the mid-1990s in precipitation and since the mid-2000s also in air and the aerosol phase. Therefore, the UBA air monitoring network contributes to the supervision of the Stockholm convention and the respective EU Regulation (2019/1021) on persistent organic pollutants. Recently further chemicals of emerging concern were included to the list of substances that are measured at the UBA air monitoring stations. Within a three-year project period, fluorinated organics such as per- and polyfluorinated substances (PFAS) and a range of current used pesticides (CUP) will be measured for the next two years in precipitation and air. This work presents the history of PAH and POP measurements at the UBA air monitoring network and the novel compounds of interest with the applied techniques for their detection and monitoring over the coming years.

As an important source of sub-micrometer particles, atmospheric new particle formation (NPF) has been observed in various environments. However, most studies provide little more than snapshots of the NPF process due to their underlying observations being limited in space and time. To obtain statistically relevant evidence on NPF across various environments, we investigated the characteristics of NPF based on a 5-year dataset of the German Ultrafine Aerosol Network (GUAN). The results were also compared with observations in previous studies, with the aim to depict a relatively complete picture of NPF in central Europe. The highest NPF occurrence frequency was observed in regional background sites, with an average of about 19 %, followed by urban background (15 %), low-mountain-range (7 %), and high Alpine (3 %) sites. The annual mean growth rate between 10 and 25 nm varied from 3.7-4.7 nm h-1, while the formation rate with same size range 10-25 nm from 0.4 to 2.9 cm-3 s-1. The contribution of NPF to ultrafine particles (UFPs) was about 13 %, 21 %, and 7 % for the urban background, regional background, and low mountain range, respectively. The influence of NPF on cloud condensation nuclei (CCN) number concentration and the aerosol extinction coefficient for NPF days was the highest in mountainous areas. These findings underscore the importance of local environments when assessing the potential impact of NPF on regional climate in models, and they also emphasize the usefulness of a long-term aerosol measurement network for understanding the variation in NPF features and their influencing factors over a regional scale.

Abstract. Atmospheric volatile organic compounds (VOC) constitute a wide range of species, acting as precursors to ozone and aerosol formation. Atmospheric chemistry and transport models (CTMs) are crucial to understanding the emissions, distribution, and impacts of VOCs. Given the uncertainties in VOC emissions, lack of evaluation studies, and recent changes in emissions, this work adapts the European Monitoring and Evaluation Programme Meteorological Synthesizing Centre – West (EMEP MSC-W) CTM to evaluate emission inventories in Europe. Here we undertake the first intensive model-measurement comparison of VOCs in two decades. The modelled surface concentrations are evaluated both spatially and temporally, using measurements from the regular EMEP monitoring network in 2018 and 2019, and a 2022 campaign. To achieve this, we utilised the UK National Atmospheric Emission Inventory to derive explicit emission profiles for individual species and employed a `tracer' method to produce pure concentrations that are directly comparable to observations. Model simulations for 2018 compare the use of two European inventories, CAMS and CEIP, and of two chemical mechanisms, CRIv2R5Em and EmChem19rc; those for 2019 and 2022 use CAMS and CRIv2R5Em only. The degree to which the modelled and measured VOCs agree varies depending on the specific species. The model successfully captures the overall spatial and temporal variations of major alkanes (e.g., ethane, n-butane) and unsaturated species (e.g., ethene, benzene), but less though for propane, i-butane, and ethyne. This discrepancy underscores potential issues in the boundary conditions for these latter species and in their primary emissions from in particular the solvent and road transport sectors. Specifically, potential missing propane emissions and issues with its boundary conditions are highlighted by large model underestimations and smaller propane to ethane ratios compared to the measurement. Meanwhile, both the model and measurement show strong linear correlations among butane isomers and among pentane isomers, indicating common sources for these pairs of isomers. However, modelled ratios of i- to n-butane and i- to n-pentane are approximately one-third of the measured ratios, which is largely driven by significant emissions of n-butane and n-pentane from the solvent sector. This suggests issues with the speciation profile of the solvent sector, or underrepresented contributions from transport and fuel evaporation sectors in current inventories, or both. Furthermore, the modelled ethene-to-ethyne and benzene-to-ethyne ratios differ significantly from measured ratios. The different model performance strongly points to shortcomings in the spatial and temporal patterns and magnitudes of ethyne emissions, especially during winter. For OVOCs, modelled and measured methanal and methylglyoxal display a good agreement, which demonstrates that the model captures the overall photo-oxidation processes reasonably well. However, the insufficiency of suitable measurements limits the evaluation of other OVOCs. Finally, the model exhibits very similar performance across simulations using different inventories, which suggests that the emission profiles are likely to exert a more significant impact on the agreement between modelled and measured data than the total emissions reported for each sector. Therefore, the future focus may need to shift towards refining these speciation profiles through for example new emission measurement campaigns to improve the model accuracy.

It is well accepted that airborne particles can induce adverse health effects dependent on the source, composition, morphology and size. Studies indicate that ultrafine particles (diameter < 100 nm) are of specific importance. Therefore, upwind and downwind field measurements of particle number size distributions (14–750 nm), nitrogen oxides, PM10 and PM1 mass concentrations were performed to derive information on sources of those types of particles from motorways. The measurement stations were located at a motorway in a rural area with flat terrain and unhindered air flow situation. The mean particle number concentration was 20,900 #/cm3 downwind and 3,400 #/cm3 upwind of the motorway. The highest total particle number concentration at the downwind station was 141,000 #/cm3. About 90

In the original publication [...].

Atmospheric volatile organic compounds (VOCs) constitute a wide range of species, acting as precursors to ozone and aerosol formation. Atmospheric chemistry and transport models (CTMs) are crucial to understanding the emissions, distribution, and impacts of VOCs. Given the uncertainties in VOC emissions, lack of evaluation studies, and recent changes in emissions, this work adapts the European Monitoring and Evaluation Programme Meteorological Synthesizing Centre – West (EMEP MSC-W) CTM to evaluate emission inventories in Europe. Here we undertake the first intensive model–measurement comparison of VOCs in 2 decades. The modelled surface concentrations are evaluated both spatially and temporally, using measurements from the regular EMEP monitoring network in 2018 and 2019, as well as a 2022 campaign. To achieve this, we utilised the UK National Atmospheric Emissions Inventory to derive explicit emission profiles for individual species and employed a tracer method to produce pure concentrations that are directly comparable to observations. The degree to which the modelled and measured VOCs agree varies depending on the specific species. The model successfully captures the overall spatial and temporal variations of major alkanes (e.g. ethane, n-butane) and unsaturated species (e.g. ethene, benzene) but less so for propane, i-butane, and ethyne. This discrepancy underscores potential issues in the boundary conditions for the latter species and in their primary emissions from, in particular, the solvent and road transport sectors. Specifically, potential missing propane emissions and issues with its boundary conditions are highlighted by large model underestimations and smaller propane-to-ethane ratios compared to the measurement. Meanwhile, both the model and measurements show strong linear correlations among butane isomers and among pentane isomers, indicating common sources for these pairs of isomers. However, modelled ratios of i-butane to n-butane and i-pentane to n-pentane are approximately one-third of the measured ratios, which is largely driven by significant emissions of n-butane and n-pentane from the solvent sector. This suggests issues with the speciation profile of the solvent sector, underrepresented contributions from transport and fuel evaporation sectors in current inventories, or both. Furthermore, the modelled ethene-to-ethyne and benzene-to-ethyne ratios differ significantly from measured ratios. The different model performance strongly points to shortcomings in the spatial and temporal patterns and magnitudes of ethyne emissions, especially during winter. For OVOCs, the modelled and measured concentrations of methanal and methylglyoxal show a good agreement, despite a moderate underestimation by the model in summer. This discrepancy could be attributed to an underestimation of contributions from biogenic sources or possibly a model overestimation of their photolytic loss in summer. However, the insufficiency of suitable measurements limits the evaluation of other OVOCs. Finally, model simulations employing the CAMS inventory show slightly better agreements with measurements than those using the Centre on Emission Inventories and Projections (CEIP) inventory. This enhancement is likely due to the CAMS inventory's detailed segmentation of the road transport sector, including its associated sub-sector-specific emission profiles. Given this improvement, alongside the previously mentioned concerns about the model's biased estimations of various VOC ratios, future efforts should focus on a more detailed breakdown of dominant emission sectors (e.g. solvents) and the refinement of their speciation profiles to improve model accuracy.

The hazard posed to human health by inhaled amorphous silica nanomaterials (aSiO2 NM) remains uncertain. Herein, we assessed the cyto- and genotoxicity of aSiO2 NM variants covering different sizes (7, 15, and 40 nm) and surface modifications (unmodified, phosphonate-, amino- and trimethylsilyl-modified) on rat alveolar epithelial (RLE-6TN) cells. Cytotoxicity was evaluated at 24 h after exposure to the aSiO2 NM variants by the lactate dehydrogenase (LDH) release and WST-1 reduction assays, while genotoxicity was assessed using different endpoints: DNA damage (single- and double-strand breaks [SSB and DSB]) by the comet assay for all aSiO2 NM variants; cell cycle progression and γ-H2AX levels (DSB) by flow cytometry for those variants that presented higher cytotoxic and DNA damaging potential. The variants with higher surface area demonstrated a higher cytotoxic potential (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_15_Phospho). SiO2_40 was the only variant that induced significant DNA damage on RLE-6TN cells. On the other hand, all tested variants (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_40) significantly increased total γ-H2AX levels. At high concentrations (28 µg/cm2), a decrease in G0/G1 subpopulation was accompanied by a significant increase in S and G2/M sub-populations after exposure to all tested materials except for SiO2_40 which did not affect cell cycle progression. Based on the obtained data, the tested variants can be ranked for its genotoxic DNA damage potential as follows: SiO2_7 = SiO2_40 = SiO2_15_Unmod > SiO2_15_Amino. Our study supports the usefulness of multiparametric approaches to improve the understanding on NM mechanisms of action and hazard prediction.

The CO, CO2 and CH4 mole fractions have been measured since 2002 at the Environmental Research Station Schneefernerhaus, which is located approximately 300 m below the summit of Zugspitze in the German Alps. Although the station is located remotely at an altitude of 2650 m a.s.l., local pollution events by snow blowers and snow groomers can be detected in the high temporal-resolution time series of seconds or minutes. Therefore, a time-consuming flagging process, carried out manually by the station manager, is necessary. To examine local influences and the effectiveness of data flagging, a 290 m long intake line to the higher Zugspitze ridge was used to measure CO, CO2 and CH4 mole fractions at a potentially less polluted location between October 2018 and October 2020. The comparison of these two time series shows that the mountain ridge measurement is almost unaffected by local pollution. It also demonstrates that the influence of local pollution events on the Schneefernerhaus measurements is successfully removed by the station manager. Only a small deviation of up to 0.24 ppm can be observed during the day between the CO2 time series of the Schneefernerhaus and the mountain ridge in winter, probably due to anthropogenic sources.

Several reports on amorphous silica nanomaterial (aSiO2 NM) toxicity have been questioning their safety. Herein, we investigated the in vivo pulmonary toxicity of four variants of aSiO2 NM: SiO2_15_Unmod, SiO2_15_Amino, SiO2_7 and SiO2_40. We focused on alterations in lung DNA and protein integrity, and gene expression following single intratracheal instillation in rats. Additionally, a short-term inhalation study (STIS) was carried out for SiO2_7, using TiO2_NM105 as a benchmark NM. In the instillation study, a significant but slight increase in oxidative DNA damage in rats exposed to the highest instilled dose (0.36 mg/rat) of SiO2_15_Amino was observed in the recovery (R) group. Exposure to SiO2_7 or SiO2_40 markedly increased oxidative DNA lesions in rat lung cells of the exposure (E) group at every tested dose. This damage seems to be repaired, since no changes compared to controls were observed in the R groups. In STIS, a significant increase in DNA strand breaks of the lung cells exposed to 0.5 mg/m3 of SiO2_7 or 50 mg/m3 of TiO2_NM105 was observed in both groups. The detected gene expression changes suggest that oxidative stress and/or inflammation pathways are likely implicated in the induction of (oxidative) DNA damage. Overall, all tested aSiO2 NM were not associated with marked in vivo toxicity following instillation or STIS. The genotoxicity findings for SiO2_7 from instillation and STIS are concordant; however, changes in STIS animals were more permanent/difficult to revert.

With the rising interest in the effects of orally ingested engineered nanomaterials (ENMs), much effort is undertaken to develop and advance intestinal in vitro models. The cytotoxic, proinflammatory, and DNA damaging properties of polyvinylpyrrolidone-capped silver (Ag-PVP) and titanium dioxide (TiO2, P25) ENM in four in vitro models of increasing complexity-from proliferating Caco-2 and HT29-MTX-E12 monocultures to long-term transwell triple cultures including THP-1 macrophages to reproduce the human intestine in healthy versus inflamed-like state-are studied. Results are compared against in vivo effects of the same ENM through intestinal tissue analysis from 28-day oral exposure studies in mice. Adverse responses are only observed in monocultures and suggest toxic potential for both ENM, typically showing stronger effects for Ag-PVP than for TiO2. By contrast, no adverse effects are observed in either the transwell cultures or the analyzed murine tissues. The data provide further support that monoculture models represent a cost and time efficient tool for early-phase hazard assessment. However, the observed similarities in morphology and ENM effects in murine intestinal tissue and the in vitro triple culture model suggest that advanced multifacetted research questions concerning oral ENM exposure are more adequately addressed by the more complex and time intensive models.

The immense diversity and constant development of nanomaterials (NMs) increase the need for a facilitated risk assessment, which requires knowledge of the modes of action (MoAs) of NMs. This necessitates a comprehensive data basis, which can be obtained using omics. Furthermore, the establishment of suitable in vitro test systems is essential to follow the 3R concept and to cope with the high number of NMs. In the present study, we aimed to compare NM effects in vitro and in vivo using a multi-omics approach. We applied an integrated data analysis strategy based on proteomics and metabolomics to four silica NMs and one titanium dioxide-based NM. For the in vitro investigations, rat alveolar epithelial cells (RLE-6TN) and rat alveolar macrophages (NR8383) were treated with different doses of NMs, and the results were compared with the effects on rat lungs after short-term inhalations and instillations. Since reactive oxygen species (ROS) production has been described as a critical biological effect of NMs, we focused on different levels of oxidative stress. Thus, we found opposite changes in proteins and metabolites related to the production of reduced glutathione in alveolar epithelial cells and alveolar macrophages, demonstrating that the MoAs of NMs depend on the model system used. Interestingly, in vivo, pathways related to inflammation were more affected than oxidative stress responses. Hence, the assignment of the observed effects to levels of oxidative stress was also different in vitro and in vivo. However, the overall classification of "active" and "passive" NMs was consistent in vitro and in vivo, suggesting that both cell lines tested are suitable for the assessment of NM toxicity. In summary, the results presented here highlight the need to carefully review model systems to decipher the extent to which they can replace in vivo assays.

Nanomaterials (NMs) can be manufactured in plenty of variants differing in their physicochemical properties. Functional assays can be highly useful to cope with the enormous variability by supporting prioritization and categorization. Oxidative potential (OP) seems to be in particular important in this context and different assays are available. However, their reliability and predictivity are not well-characterized. This study compares four different test methods for measuring NM OP. Reactive oxygen species (ROS) generation was measured on a set of 35 different materials, all extensively characterized with respect to physicochemical properties and most of them with respect to toxicity. Different acellular assays were applied, namely electron spin resonance (ESR) spectroscopy using CPH spin probe and DMPO spin trap, and the ferric reduction ability of serum (FRAS) assay. In addition, protein carbonylation as a marker for oxidative protein damage was analyzed in NRK-52E cells. All assays were assessed individually for their predictivity compared to established toxicological endpoints. We also aimed to identify the optimal assay combination using multivariate logistic regression and other statistical measures. BET surface area-based doses were more suitable to relate surface reactivity to toxicity. In addition, normalization to the deposited dose was advantageous for cellular assays as it improved the predictivity for in vitro as well as in vivo toxicity. The carbonylation assay, potentially in combination with ESR (DMPO spin trap) or FRAS assay, led to the best predictive performance. In summary, we propose a testing strategy for NM OP and demonstrated the applicability in an extended case study on 35 materials. This work is an important contribution towards reliable grouping and testing strategies for NMs.

TiO2 nanomaterials are among the most commonly produced and used engineered nanomaterials (NMs) in the world. There is controversy regarding their ability to induce inflammation-mediated lung injuries following inhalation exposure. Activation of the NACHT, LRR and PYD domains-containing protein 3 (NALP3) inflammasome and subsequent release of the cytokine interleukin (IL)-1β in pulmonary macrophages has been postulated as an essential pathway for the inflammatory and associated tissue-remodeling effects of toxic particles. Our study aim was to determine and rank the IL-1β activating properties of TiO2 NMs by comparing a large panel of different samples against each other as well as against fine TiO2, synthetic amorphous silica and crystalline silica (DQ12 quartz). Effects were evaluated in primary bone marrow derived macrophages (BMDMs) from NALP3-deficient and proficient mice as well as in the rat alveolar macrophage cell line NR8383. Our results show that specific TiO2 NMs can activate the inflammasome in macrophages albeit with a markedly lower potency than amorphous SiO2 and quartz. The heterogeneity in IL-1β release observed in our study among 19 different TiO2 NMs underscores the relevance of case-by-case evaluation of nanomaterials of similar chemical composition. Our findings also further promote the NR8383 cell line as a promising in vitro tool for the assessment of the inflammatory and inflammasome activating properties of NMs.

Abstract Nanomaterials (NMs) can be produced in plenty of variants posing several challenges for NM hazard and risk assessment. Metabolomic profiling of NM-treated cells and tissues allows for insights into underlying Mode-of-Action (MoA) and offers several advantages in this context. It supports the description of Adverse Outcome Pathways (AOPs) and, therefore, tailored AOP-based hazard testing strategies. Moreover, it bears great potential for biomarker discovery supporting toxicity prediction. Here, we applied metabolomics profiling to cells treated with four well-selected SiO2 variants, differing in structure, size and surface charge. TiO2 NM-105 served as a benchmark. Responses were studied in vitro in rat lung epithelial cells (RLE-6TN) and alveolar macrophages (NR8383) and compared to in vivo responses in rat lung tissues obtained from in vivo instillation and short-term inhalation studies (STIS). Time- and concentration-dependent changes were observed in both in vitro models but with cell-type specific responses. Overall, the levels of lipids and biogenic amines (BAs) tended to increase in epithelial cells but decreased in macrophages. Many identified metabolites like Met-SO, hydroxy-Pro and spermidine were related to oxidative stress, indicating that oxidative stress contributes to the MoA for the selected NMs. Several biomarker candidates such as Asp, Asn, Ser, Pro, spermidine, putrescine and LysoPCaC16:1 were identified in vitro and verified in vivo. In this study, we successfully applied a metabolomics workflow for in vitro and in vivo samples, which proved to be well suited to identify potential biomarkers, to gain insights into NM structure–activity relationship and into the underlying MoA.

A total of 10 years of hourly aerosol and gas data at four rural German stations have been combined with hourly back trajectories to the stations and inventories of the European Emissions Database for Global Atmospheric Research (EDGAR), yielding pollution maps over Germany of PM10, particle number concentrations, and equivalent black carbon (eBC). The maps reflect aerosol emissions modified with atmospheric processes during transport between sources and receptor sites. Compared to emission maps, strong western European emission centers do not dominate the down-wind concentrations because their emissions are reduced by atmospheric processes on the way to the receptor area. PM10, eBC, and to some extent also particle number concentrations are rather controlled by emissions from southeastern Europe from which pollution transport often occurs under drier conditions. Newly formed particles are found in air masses from a broad sector reaching from southern Germany to western Europe, which we explain with gaseous particle precursors coming with little wet scavenging from this region. Annual emissions for 2009 of PM10, BC, SO2, and NOx were accumulated along each trajectory and compared with the corresponding measured time series. The agreement of each pair of time series was optimized by varying monthly factors and annual factors on the 2009 emissions. This approach yielded broader summer emission minima than published values that were partly displaced from the midsummer positions. The validity of connecting the ambient concentration and emission of particulate pollution was tested by calculating temporal changes in eBC for subsets of back trajectories passing over two separate prominent emission regions, region A to the northwest and B to the southeast of the measuring stations. Consistent with reported emission data the calculated emission decreases over region A are significantly stronger than over region B.

Engineered nanomaterials (ENM) have a widespread presence in human life and are components of many products and applications. This warrants an easy and fast evaluation of potential environmental risks. However, so far this is hampered by the multitude of different nanomaterials on the markets in addition to the many variations in form, size and surface modifications. Testing of each variation of ENM is not manageable, and hence the development and application of fast risk screening tools for ENMs is discussed. Here, we present the development of a scoring scheme with regard to ENM environmental risks under consideration of the two compartments water and soil. It allows for the ranking of ENM according to their environmental fate and hazard by taking into account criteria that are meaningful and relevant for ENM. The selection of the criteria is based on conceptual considerations, existing knowledge, and experimental work including transport and transformation studies as well as aquatic and terrestrial toxicity tests. The allocation of the ENM to the scores informs on the potential for transport and transformation and the hazard potential. Fate and hazard scores are subsequently combined into one risk score (1-10 for aquatic compartment, 1-7 for terrestrial compartment). The risk score has the intention to indicate which ENM may need prioritization for further action, i.e. with regard to the degree of detail for further testing or modelling. The applicability and consistency of the scoring schemes were assessed by taking different chemical species (e.g. of Ag, TiO2, SiO2, Cu, Fe) of ENM in various modifications (e.g. different shapes and coatings) into account. In conclusion, the established scoring schemes were found to be applicable to rank ENM according to their environmental fate and hazard potential, and thus to their environmental risk potential.