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The high carbon monoxide content in the urban atmosphere is one of the most important indicators of poor air quality in megacities such as Moscow. This study is to evaluate the importance of wind speed, air temperature, and relative air humidity for predicting the concentrations of carbon monoxide for the day ahead using a simplified one-dimensional quasistationary statistical model. It is shown that the concentration of carbon monoxide in the Moscow atmosphere is determined by a combination of internal (previous days CO concentration) and external (meteorological conditions) factors. The variation of carbon monoxide concentration at one station differs from the variation at another station due to the differences in local conditions. Taking into account wind speed and air temperature increases the predictive value of the onedimensional quasi-stationary statistical model for most of the stations. In contrast to wind, relative air humidity decreases the predictive value of the model for most of the stations. This means that meteorological factors considered in this study could have different effects on predicting carbon monoxide concentration in the case of Moscow. The data from the Balchug weather station, located in the city center, offers a more accurate CO concentration forecast for most Moscow stations compared to the VDNKh weather station. For a more complete description of the influence of meteorological conditions on the predicted low concentration of gases, it is useful to take into account the model wind direction, surface air pressure, and the intensity of mixing in the urban boundary layer.

The increase in heavy metal concentrations in the air, especially after the Industrial Revolution, is notable for the scientific world because of the adverse effects that threaten environmental and human health. Among the trace elements, nickel (Ni) is carcinogenic, and all barium (Ba) compounds are toxic. Trace elements are critical for human and environmental health. Their threat further increases, especially in the urban areas and surroundings with a high population. In urban areas, the trace element contamination in the airborne can be reduced using plants. However, which plant and plant organs absorb trace elements could not be determined. In the present study, Ni and Ba concentrations in the branch, wood, and leaf samples of 14 species collected from the city center of Mersin province were determined. As a result, broad-leaved species' Ni and Ba concentrations in their leaf sample were generally higher than other species. Almost all species had the lowest Ni and Ba concentrations in their wood samples. Among these 14 species, it was found that Ni concentration was very high, especially in non-washed leaves of Platanus orientalis, Photinia serrulata, and Citrus reticulate, and Ba concentration was very high in Citrus reticulata, Chamaecyparis lawsoniana, Laurus nobilis, and Acer hyrcanum. Using broad-leaved species in urban areas where pollution is at high levels will significantly contribute to reducing Ni and Ba pollution. It is recommended that these points be considered in future urban landscaping projects. [ABSTRACT FROM AUTHOR]

The atmospheric concentrations of seventeen elements were measured in air filters at the Finnish Meteorological Institute station in Helsinki, Finland, during a period of 44 years (1962–2005). The mean annual concentrations were calculated and are presented from the lowest values to the highest ones Cr < Ni < Ti < Br < V < Mn < Cu < Zn < Cl < Al < Fe < K < Ca < Na < Pb < Si < S. Most of the elements (Fe, Si, Ti, K, Ca, Zn, Br, Pb, V, Ni, S, Cr, Na, Al, and Cl) present higher values during spring and winter season, while in summer the elements (Ti, Ca, S, and Na) are found in higher concentrationsdue to the weather conditions across seasons and the sources and emissions of air pollutants. There is a strong correlation between the elements (V-Ni, Si-Pb, Fe-Ca, V-Cr, Si-K, K-Ca, Fe-Ti, K-Na, Si-Ca, and V-S), indicating their common source. The identification of the sources of trace elements was performed based on positive matrix factorization analysis, using SoFi software. Four Suspended Particulate Matter (PM) sources were identified: road dust (due to usage of leaded fuel), heavy oil combustion/secondary sulfates, traffic emissions, and natural dust (soil). For the total of 44 years studied, significant decreases in concentrations were observed for all elements, most of which were over 50%: Na (−74%), Al (−86%), Si (−88%), S (−82%), K (−82%), Ca (−89%), Ti (−80%), V (−89%), Cr (−82%), Mn (−77%), Fe (−77%), Ni (−61%), Zn (−72%), and Pb (−95%). In general, a significant decline has been observed in the majority of the elemental concentrations since the end of the 1970s, underlying the effectiveness of different environmental policies that have been applied during the last few decades. [ABSTRACT FROM AUTHOR]

Oxygen content is one of the most important indices of the atmospheric air quality, on which the health and working capacity of the population depend. Many researchers do not consider a constant decrease in oxygen concentration to be dangerous for human health. Nevertheless, a local drop in the oxygen content in the air near the highways can cause negative consequences for human health. Undoubtedly, the constant growth of motorization in Tashkent leads to intensive oxygen absorption from the urban atmosphere to realize the fuel combustion processes. The purpose of this study is to assess the decrease in oxygen concentration in the air of Tashkent city near the highways due to the motor transport traffic. As was experimentally determined, a decrease in the oxygen concentration in the atmospheric air was observed near the highways; and the intensity of the decrease was related to the intensity of vehicle traffic. During rush hours, oxygen concentration near the highways could reach the values that are hazardous to humans, up to 19.6 - 19.5% O2. A modified Kitsenko equation was proposed to perform an express assessment of the oxygen concentration; the authors have introduced the coefficients of irregularity of movement into this equation. The proposed method will make it possible to assess the oxygen content by an indirect indicator (traffic intensity) and timely inform the population about the air quality.

Oxygen content is one of the most important indices of the atmospheric air quality, on which the health and working capacity of the population depend. Many researchers do not consider a constant decrease in oxygen concentration to be dangerous for human health. Nevertheless, a local drop in the oxygen content in the air near the highways can cause negative consequences for human health. Undoubtedly, the constant growth of motorization in Tashkent leads to intensive oxygen absorption from the urban atmosphere to realize the fuel combustion processes. The purpose of this study is to assess the decrease in oxygen concentration in the air of Tashkent city near the highways due to the motor transport traffic. As was experimentally determined, a decrease in the oxygen concentration in the atmospheric air was observed near the highways; and the intensity of the decrease was related to the intensity of vehicle traffic. During rush hours, oxygen concentration near the highways could reach the values that are hazardous to humans, up to 19.6 - 19.5% O2. A modified Kitsenko equation was proposed to perform an express assessment of the oxygen concentration; the authors have introduced the coefficients of irregularity of movement into this equation. The proposed method will make it possible to assess the oxygen content by an indirect indicator (traffic intensity) and timely inform the population about the air quality. [ABSTRACT FROM AUTHOR]

In recent years, studies of heavy metal air pollution have increasingly gone beyond determining total concentrations of individual toxic metals. Chemical fractionation of potentially toxic elements in airborne particles is becoming an important part of these studies. This review covers the articles that have been published over the last three decades. Attention was paid to the issue of atmospheric aerosol sampling, sample pretreatment, sequential extraction schemes and conditions of individual extractions. Geochemical forms of metals occurring in the air in urban areas were considered in detail. Based on the data sets from chemical fractionation of particulate matter samples by three sequential extraction procedures (SEPs)—Fernández Espinosa, BCR and Chester's—the compilation of the chemical distribution patterns of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn was prepared. The human health risk posed by these toxic and/or carcinogenic elements via inhalation of atmospheric particles was estimated for two categories of polluted urban areas: the commonly encountered pollution level and the high pollution level. [ABSTRACT FROM AUTHOR]

Tire wear particles (TWPs) containing tire wear chemicals (TWCs) are of global concern due to their large emissions and potential toxicity. However, TWP contributions to urban fine particles are poorly understood. Here, 72 paired gas-phase and PM 2.5 samples were collected in the urban air of the Pearl River Delta, China. The concentrations of 54 compounds were determined, and 28 TWCs were detected with total concentrations of 3130-317,000 pg/m 3 . Most p-phenylenediamines (PPDs) were unstable in solvent, likely leading to their low detection rates. The TWCs were mainly (73 ± 26%) in the gas phase. 2-OH-benzothiazole contributed 82 ± 21% of the gas-phase TWCs and benzothiazole-2-sulfonic acid contributed 74 ± 18% of the TWCs in PM 2.5 . Guangzhou and Foshan were "hotspots" for atmospheric TWCs. Most TWC concentrations significantly correlated with the road length nearby. More particulate TWCs were observed than model predictions, probably due to the impacts of nonexchangeable portion and sampling artifacts. Source apportionment combined with characteristic molecular markers indicated that TWPs contributed 13 ± 7% of urban PM 2.5 . Our study demonstrates that TWPs are important contributors to urban air pollution that could pose risks to humans. There is an urgent need to develop strategies to decrease TWP emissions, along with broader urban air quality improvement strategies.

The aim of this study was to evaluate possible sources, toxicity and human health risk via inhalation of particulate matter (PM10) bound polycyclic aromatic hydrocarbons (PAHs). During November 2013–January 2014, 54 PM10 samples were collected from a tropical city of north-west India and analysed for sixteen priority PAHs (∑16PAHs). The concentration of ∑16PAHs ranged between 18 and 164 ng m−3 with an average of 96 ± 48 ng m−3. The concentration of seven carcinogenic PAHs (C-PAHs) accounted for 22.68% of ∑16PAHs. The carcinogenic potency of 16 PAHs as benzo(a)pyrene equivalent (BaPeq) ranged between 2.49 and 11.37 ng m−3. Composition profile and results of source apportionment indices suggested mixed pyrogenic sources. Back trajectory analysis revealed that the level of PAHs in ambient air (PM10) at Amritsar might have been influenced by long-range atmospheric transport and various local emission sources. The BaPeq-based PAH concentrations are used to estimate daily exposure level through inhalation pathways. The estimated inhalation cancer risk (CR) for human adults (8.5 × 10–9–6.5 × 10–6) and children (1.6 × 10–8–1.2 × 10–5) was within the stipulated acceptable limit. However, due to limitations in the exposure through inhalation, and lack of data on exposure through diet, total daily intake of PAHs and CR could not be estimated. [ABSTRACT FROM AUTHOR]

Due to the link between air pollutants and human health, reliable model estimates of hourly pollutant concentrations are of particular interest. Artificial neural networks (ANNs) are powerful modeling tools capable of reproducing the observed variations in pollutants with high accuracy. We present a simple ANN for the city of Hamburg that estimated the hourly NO2 concentration. The model was trained with a ten-year dataset (2007–2016), tested for the year 2017, and then applied to assess the efficiency of countermeasures against air pollution implemented since 2018. Using both meteorological data and describing the weekday dependent traffic variabilities as predictors, the model performed accurately and showed high consistency over the test data. This proved to be very efficient in detecting anomalies in the time series. The further the prediction was from the time of the training data, the more the modeled data deviated from the measured data. Using the model, we could detect changes in the time series that did not follow previous trends in the training data. The largest deviation occurred during the COVID-19 lockdown in 2020, when traffic volumes decreased significantly. Concluding our case study, the ANN based approach proved suitable for modeling the NO2 concentrations and allowed for the assessment of the efficiency of policy measures addressing air pollution.

Compared to soil or aquatic ecosystems, the atmosphere is still an underexplored environment for microbial diversity. In this study, we surveyed the composition, variability and sources of microbes (bacteria and fungi) in the near surface atmosphere of a highly populated area, spanning ~ 4,000 Km2 around the city center of Madrid (Spain), in different seasonal periods along two years. We found a core of abundant bacterial genera robust across space and time, most of soil origin, while fungi were more sensitive to environmental conditions. Microbial communities showed clear seasonal patterns driven by variability of environmental factors, mainly temperature and accumulated rain, while local sources played a minor role. We also identified taxa in both groups characteristic of seasonal periods, but not of specific sampling sites or plant coverage. The present study suggests that the near surface atmosphere of urban environments contains an ecosystem stable across relatively large spatial and temporal scales, with a rather homogenous composition, modulated by climatic variations. As such, it contributes to our understanding of the long-term changes associated to the human exposome in the air of highly populated areas.

The purpose of this study was to study the spatial and temporal variation of BTEX in the ambient air of Leon, Guanajuato, Mexico, to assess the inhalation health risk to the local population from exposure to these compounds. BTEX were monitored using passive samplers during two sampling seasons (rainy 2019 and cold dry 2020), and samples were analyzed by gas chromatography with flame ionization detection. BTEX ratios and meteorological analysis suggested that the concentrations were mainly influenced by vehicular and local sources located to the SE of the study area. The sum of average concentrations of BTEX in rainy and cold dry seasons were of 3.52 ± 0.36 µg m−3 and 4.11 ± 0.38 µg m−3, respectively. Mean concentrations were of 0.74, 1.59, 0.48, and 0.69 µg m−3, for benzene, toluene, ethylbenzene, and p-xylene, respectively. The highest levels of BTEX were found in sites with an urban land-use type of medium-intensity industrial zones with high population density. The lower BTEX concentrations found during the rainy season were probably due to higher solar radiation and temperatures that favored their photochemical degradation. Bi-variate and multivariate analysis showed that the BTEX species were strongly correlated with each other and with temperature and solar radiation, indicating that they originated from common sources. Benzene and toluene correlated strongly with CO and SO2, indicating that they could originate from vehicular exhaust emissions and high-sulfur fuel combustion sources. The health risk assessment showed that the Leon city adult population is at possible risk of developing cancer in their lifetime due to exposure to the measured benzene levels, but indicated no risk of contracting respiratory and cardiovascular diseases due to inhalation of BTEX. The results suggest the need for BTEX emissions reduction policies in the study area, as well as the establishment of a Mexican standard that regulates the maximum permissible limit of these pollutants in ambient air in order to protect the health of the population. [ABSTRACT FROM AUTHOR]

In recent years, studies of heavy metal air pollution have increasingly gone beyond determining total concentrations of individual toxic metals. Chemical fractionation of potentially toxic elements in airborne particles is becoming an important part of these studies. This review covers the articles that have been published over the last three decades. Attention was paid to the issue of atmospheric aerosol sampling, sample pretreatment, sequential extraction schemes and conditions of individual extractions. Geochemical forms of metals occurring in the air in urban areas were considered in detail. Based on the data sets from chemical fractionation of particulate matter samples by three sequential extraction procedures (SEPs)—Fernández Espinosa, BCR and Chester’s—the compilation of the chemical distribution patterns of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn was prepared. The human health risk posed by these toxic and/or carcinogenic elements via inhalation of atmospheric particles was estimated for two categories of polluted urban areas: the commonly encountered pollution level and the high pollution level.

Abstract Background Previously we found that DNA adducts were accumulated in the lungs of the rats exposed to ambient air in the Tokyo metropolitan area. To examine chronological change in in vivo mutagenicity of airborne particles, extracts produced from samples of total suspended particulates (TSP) collected from urban air in 1980, 1990, and 2010 in the Tokyo metropolitan area were intratracheally administered into the lungs of gpt delta mice, and differences in mutation and mutant frequency were determined by using the gpt assay. In vivo mutations induced by the extracts were characterized and mutation hotspots were identified by DNA sequencing of the mutated gpt gene. Results Administration of the 1990 extract at a dose of 0.3 mg/animal significantly elevated total mutant frequency to 3.3-times that in vehicle control, and the in vivo mutagenicity of the extract (induced mutation frequency per milligram extract) was estimated to be 2.0- and 2.4-times higher than that of the 2010 and 1980 extract, respectively. G-to-A transition was the most common base substitution in the vehicle control mice. However, administration of the 1990 extract increased the frequency of G-to-T transversion, which is a landmark base substitution induced by oxidative stress; furthermore, when the extract was administered at a dose of 0.15 mg, the mutant and mutation frequencies of G-to-T transversion were significantly increased to frequencies comparable with those of G-to-A transition. Similar increases in the mutant and mutation frequencies of G-to-T transversion were observed after administration of the 2010 extract. Hotspots (mutation foci identified in three or more mice) of G-to-A transition mutations at nucleotides 64 and 110 were induced by the 1980, 1990, and 2010 extracts; a hotspot of G-to-T transversions at nucleotide 406 was also induced by the 2010 extract. Previously, we showed that diesel exhaust particles or their extract, as well as 1,6-dinitropyrene, administered to mice induced these hotspots of G-to-A transitions. Conclusions The results of the present study suggested that mutagenesis induced by extracts produced from TSP collected in the Tokyo metropolitan area induced in vivo mutagenicity via the same mechanism underlying the induction of in vivo mutagenicity by components of diesel exhaust.

This study is aimed to determine the occurrence of organophosphorus flame retardants (OPFRs) in atmospheric particulate matter with an aerodynamic diameter of less than 1 µm (PM1). The analytical method is based on Soxhlet extraction and a clean-up step with Florisil solid phase extraction (SPE). Detection and quantification was performed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Validation included laboratory and field blank tests as well as the determination of the method efficiency using spiked quartz filters with 20 ng and 200 ng of OPFR mixture. Ambient air PM samples with particle concentrations between 4 and 26 µg/m3 were collected at an urban background site in Barcelona under contrasting meteorological conditions in order to study occurrence of OPFRs in relation to particle loads. In these samples, OPFRs were detected at levels ranging from a few pg/m3 to 1200 pg/m3 and substantial correlations were observed between the levels of certain OPFRs and atmospheric particle loadings. The presence of individual compounds in pg/m3 concentrations levels in the sub-micron PM mode (PM1) at an urban background site indicates a considerable exposure to these compounds for the human population in this area. This is the first study to determine OPFR in PM1.

Photochemical aging of volatile organic compounds (VOCs) in the atmosphere is an important source of secondary organic aerosol (SOA). To evaluate the formation potential of SOA at an urban site in Lyon (France), an outdoor experiment using a Potential Aerosol Mass (PAM) oxidation flow reactor (OFR) was conducted throughout entire days during January-February 2017. Diurnal variation of SOA formations and their correlation with OH radical exposure (OHexp), ambient pollutants (VOCs and particulate matters, PM), Relative Humidity (RH), and temperature were explored in this study. Ambient urban air was exposed to high concentration of OH radicals with OHexp in range of (0.2–1.2)×1012 molecule/(cm3•sec), corresponding to several days to weeks of equivalent atmospheric photochemical aging. The results informed that urban air at Lyon has high potency to contribute to SOA, and these SOA productions were favored from OH radical photochemical oxidation rather than via ozonolysis. Maximum SOA formation (36 µg/m3) was obtained at OHexp of about 7.4 × 1011molecule/(cm3•sec), equivalent to approximately 5 days of atmospheric oxidation. The correlation between SOA formation and ambient environment conditions (RH & temperature, VOCs and PM) was observed. It was the first time to estimate SOA formation potential from ambient air over a long period in urban environment of Lyon. Image, graphical abstract [ABSTRACT FROM AUTHOR]

We characterized the composition, diversity, and potential bacterial aerosol sources in Athens’ urban air by DNA barcoding (analysis of 16S rRNA genes) during three seasons in 2019. Air samples were collected using the recently developed Rutgers Electrostatic Passive Sampler (REPS). It is the first field application of REPS to study bacterial aerosol diversity. REPS samplers captured a sufficient amount of biological material to demonstrate the diversity of airborne bacteria and their variability over time. Overall, in the air of Athens, we detected 793 operational taxonomic units (OTUs), which were fully classified into the six distinct taxonomic categories (Phylum, Class, Order, etc.). These OTUs belonged to Phyla Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Fusobacteria. We found a complex community of bacterial aerosols with several opportunistic or potential pathogens in Athens’ urban air. Referring to the available literature, we discuss the likely sources of observed airborne bacteria, including soil, plants, animals, and humans. Our results on bacterial diversity are comparable to earlier studies, even though the sampling sites are different or geographically distant. However, the exact functional and ecological role of bioaerosols and, even more importantly, their impact on public health and the ecosystem requires further air monitoring and analysis.

Prior studies have shown that people of color (POC) in the United States are exposed to higher levels of pollution than non-Hispanic White people. We show that the city of Denver, Colorado, displays similar race- and ethnicity-based air pollution disparities by using a combination of high-resolution satellite data, air pollution modeling, historical demographic information, and areal apportionment techniques. TROPOMI NO 2 columns and modeled PM 2.5 concentrations from 2019 are higher in communities subject to redlining. We calculated and compared Spearman coefficients for pollutants and race at the census tract level for every city that underwent redlining to contextualize the disparities in Denver. We find that the location of polluting infrastructure leads to higher populations of POC living near point sources, including 40% higher Hispanic and Latino populations. This influences pollution distribution, with annual average PM 2.5 surface concentrations of 6.5 μg m -3 in census tracts with 0-5% Hispanic and Latino populations and 7.5 μg m -3 in census tracts with 60-65% Hispanic and Latino populations. Traffic analysis and emission inventory data show that POC are more likely to live near busy highways. Unequal spatial distribution of pollution sources and POC have allowed for pollution disparities to persist despite attempts by the city to rectify them. Finally, we identify the core causes of the pollution disparities to provide direction for remediation.

Air pollution occurs when harmful or excessive quantities of substances including gases, solid particulates, and biological molecules are introduced into the atmosphere. The analysis of the relationship between air pollutants and meteorological factors can provide important information about air pollution. The aim of this study is to examine and explore the relationship between the different monitored air pollutant concentrations such as carbon-monoxide (CO), nitrogen-oxides (NOx), ozone (O3), particulate matter (PM10), and sulphur-dioxide (SO2) and the selected meteorological factors such as wind speed, temperature, precipitation, and atmospheric pressure. The investigation is based on data observed during a 10-year-long measurement period (2004-2014) in the city of Veszprem located in the western part of Hungary, in the Transdanubia region. In the present research, regression analysis was the chosen statistical tool for the investigation. The analysis found that there is a moderate or a weak relation between the air pollutant concentrations and the meteorological factors. [ABSTRACT FROM AUTHOR]

Bio-aerosol is an emerging pollutant of the technological age. Air pollution related episodes that are a region-specific phenomenon in our atmosphere, with bio-aerosols being the main area of the problem. The present research was focused on assessing the particulate, and culturable concentration of bacteria at five different spatially located sites in the Rajkot city and surroundings, in the western part of India. The highest (108.33 × 109 CFU m−3) and lowest (318 × 103 CFU m−3) bacterial concentrations were found in dump site and residential area, respectively. With reference to particulate concentration, higher (101.79 ± 8.09) concentrations were reported in the industrial area than other sampling locations. All sampling sites under the present study displayed greater variability of bacteria than that of particle concentration. The growth potential of various bacterial isolates from perspective bioaerosol was measured spectroscopically by measuring OD at 600 nm in rich medium. The isolate 1A displayed significantly higher growth compared to all other isolates after 24 h. Outcomes of the current work suggested that bacterial concentration was observed in the respirable fraction (< 2.5 μm) and so had the potential to penetrate the deeper part of the lungs. In addition, meteorological parameters (i.e., wind speed, temperature, and relative humidity) were measured to understand whether they had any effect on biotic matter. The temperature and relative humidity are the most important meteorological parameters responsible for the enhanced viability of bacteria. Land use and land cover feature were also studied to understand the spatial characteristics of bio-aerosol in the study area. This viewpoint summarizes available information on bio-aerosols and its impact on human health, devising strategies to understand characteristics of bio-aerosols and emphasizing the vital gaps in available knowledge such as to develop a relationship between biological agents and solid/liquid or a mixture of both to the assessment of dispersion behavior and toxicological nature during exposure. [ABSTRACT FROM AUTHOR]

Abstract Based on distinct land-use categories, a sampling campaign was carried out at eight locations across Toronto and the Greater Toronto Area in 2016–2017. Source sectors' dependent patterns of atmospheric concentrations of 9 organophosphate esters (OPEs), 9 polybrominated diphenyl ethers (PBDEs) and 5 novel flame retardants (NFRs) showed dominance of OPEs and PBDEs at highly commercialised urban and traffic sites, while NFRs, were dominant at residential sites. Overall, average concentrations of Σ 9 OPEs (1790 pg/m3) were two orders of magnitude higher than Σ 9 PBDEs (9.17 pg/m3) and Σ 5 NFRs (8.14 pg/m3). The atmospheric concentrations of given chemical classes also showed a general trend of lower levels in winter as compared to summer months. Statistically significant negative correlations between the natural logarithm of concentrations and inverse of temperature for some OPEs and PBDEs highlighted the role of volatilization from local sources at given sites as primarily influencing their atmospheric concentrations. Overall, this study adds to the current knowledge of urban settings as a major emitter of the chemicals of emerging concern and their replacements, as well as the ongoing problem of phased out PBDEs due to their presence in existing inventories of commercial/recycled products. It is recommended that long-term monitoring programs targeting flame retardants (FRs) include urban sites, which provide an early indicator of effectiveness of control measures of targeted FRs, while at the same time providing information on emission sources and trends of replacement FR chemicals. Graphical abstract Image 1 Highlights • Source sector based measurements of FR classes were made in urban air. • OPEs were two orders of magnitude higher than PBDEs and NFRs in Toronto air. • Highly commercialised urban and traffic sites dominate the concentrations' profile. • Lack of strong gradient within sites suggests multitude of sources of FRs to air. Source sectors based concentrations of three classes of flame retardants in an urban environment. [ABSTRACT FROM AUTHOR]

This study is aimed to determine the occurrence of organophosphorus flame retardants (OPFRs) in atmospheric particulate matter with an aerodynamic diameter of less than 1 μm (PM1). The analytical method is based on Soxhlet extraction and a clean-up step with Florisil solid phase extraction (SPE). Detection and quantification was performed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Validation included laboratory and field blank tests as well as the determination of the method efficiency using spiked quartz filters with 20 ng and 200 ng of OPFR mixture. Ambient air PM samples with particle concentrations between 4 and 26 μg/m3 were collected at an urban background site in Barcelona under contrasting meteorological conditions in order to study occurrence of OPFRs in relation to particle loads. In these samples, OPFRs were detected at levels ranging from a few pg/m3 to 1200 pg/m3 and substantial correlations were observed between the levels of certain OPFRs and atmospheric particle loadings. The presence of individual compounds in pg/m3 concentrations levels in the sub-micron PM mode (PM1) at an urban background site indicates a considerable exposure to these compounds for the human population in this area. This is the first study to determine OPFR in PM1. [ABSTRACT FROM AUTHOR]

Traffic emits a considerable amount of aerosol particles in urban areas and has also recently been shown to be a significant source of sub-3 nm particles. In this study, the concentration of sub-3 nm particles, here referred to as nanocluster aerosol (NCA), was continuously measured with 1 s resolution in a busy street canyon in the city of Helsinki, Finland, for a month period in 2017. NCA concentrations were carefully analyzed with respect to the time of day, the wind direction, the condensation sink, the concentration of sub-7 nm particles, the total particle size distribution, and the CO 2 concentration, from which the emission factors for the NCA were calculated. The concentration of the NCA seemed to follow a similar trend to that of sub-7 nm particles. Diurnal variation of the NCA concentration divided into weekdays and weekends and sorted according to the wind direction followed the amount traffic. The NCA concentration was at highest when wind was blowing directly from the road, during the rush hours or when the condensation sink calculated from the particle size distributions was low. The NCA concentration was in line with the traffic-related nucleation mode of the size distribution and its diurnal variation, and the NCA fraction comprised a relatively large part of the total particle number concentration. Average emission factors for the NCA and sub-7 nm particles were 9.36 ⋅ 10 14   kg fuel − 1 and 2.73 ⋅ 10 15   kg fuel − 1 , respectively. Diurnal variation of the emission factors showed an increase in the night, which may result from a dependency of the emission factors on traffic composition, temperature, condensation sink or the driving mode of vehicles. [ABSTRACT FROM AUTHOR]

This paper investigates the relation of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in air samples with meteorological parameters (temperature, atmospheric pressure and relative humidity) using the Kohonen self-organizing map (SOM). Both gas- and particle-adsorbed phase of 20 PCB congeners and 7 OCPs including the three new ones (α-HCH, β-HCH, and γ-HCH) listed in the Stockholm Convention were collected during a one-year period at urban locations in Zagreb (Croatia). Moving beyond existing studies, the SOM analysis showed that the meteorological characteristics of transient seasons such as spring had no influence on the dissimilarities in the behavior of PCBs and OCPs. Towards the identification of pollutant spatial patterns, the SOM did not isolate a clear phenomenon probably due to the absence of local pollution sources contributing to the elevated concentrations of these compounds. Overall, our results have shown that the SOM method, by recognizing significant differences among PCB and OCP seasonality, could be recommended in the analysis of pollutant distribution depending on temperature and atmospheric pressure. [ABSTRACT FROM AUTHOR]

The identification of airborne bacteria has traditionally been performed by retrieval in culture media, but the bacterial diversity in the air is underestimated using this method because many bacteria are not readily cultured. Advances in DNA sequencing technology have produced a broad knowledge of genomics and metagenomics, which can greatly improve our ability to identify and study the diversity of airborne bacteria. However, researchers are facing several challenges, particularly the efficient retrieval of low-density microorganisms from the air and the lack of standardized protocols for sample collection and processing. In this study, we tested three methods for sampling bioaerosols — a Durham-type spore trap (Durham), a seven-day recording volumetric spore trap (HST), and a high-throughput 'Jet' spore and particle sampler (Jet) — and recovered metagenomic DNA for 16S rDNA sequencing. Samples were simultaneously collected with the three devices during one week, and the sequencing libraries were analyzed. A simple and efficient method for collecting bioaerosols and extracting good quality DNA for high-throughput sequencing was standardized. The Durham sampler collected preferentially Cyanobacteria , the HST Actinobacteria , Proteobacteria and Firmicutes , and the Jet mainly Proteobacteria and Firmicutes . The HST sampler collected the largest amount of airborne bacterial diversity. More experiments are necessary to select the right sampler, depending on study objectives, which may require monitoring and collecting specific airborne bacteria. [ABSTRACT FROM AUTHOR]

The temporal variations and major sources of polycyclic aromatic hydrocarbons (PAH) intrinsic to PM 10 were investigated over a tropical urban atmosphere on the Indo-Gangetic Plain (IGP) and for the first time over a high altitude urban atmosphere at eastern Himalaya in India. Samples were collected over Kolkata, a megacity and Darjeeling, a high altitude (2200 m asl) hill station in eastern India during the dry season (October 2015–May 2016). Fourteen PAHs were detected and quantified over Kolkata and Darjeeling during three consecutive seasons, viz., post-monsoon, winter and pre-monsoon. The total-PAHs concentrations were in the order of winter (78.08–146.71 ngm − 3 ) > post-monsoon (83.42–113.52 ngm − 3 ) > pre-monsoon (37.65–109.27 ngm − 3 ) at Kolkata, whereas post-monsoon (22.72–36.60 ngm − 3 ) > winter (8.52–28.43 ngm − 3 ) > pre-monsoon (5.45–13.34 ngm − 3 ) at Darjeeling. The observed seasonality of PAHs at Kolkata vis-a-vis Darjeeling has been explored in the light of anthropogenic activities, boundary layer dynamics and meteorological parameters such as temperature, relative humidity, wind speed and solar radiation. Negative correlation was observed between total-PAHs and temperature, wind speed and solar radiation over Kolkata and Darjeeling. The positive matrix factorization (PMF) model calculations suggested that coal (26%), petrol (24%) and diesel (17%) combustion, commercial and household kitchens (18%) and municipal solid waste incineration (15%) are the possible contributors to the PM 10 associated PAHs over Kolkata whereas diesel (37%), commercial and household kitchens (23%), coal (21%) and petrol (20%) are the possible PM 10 associated PAH sources over Darjeeling. [ABSTRACT FROM AUTHOR]

The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and from September to October 2016 with active high-volume sampler. The total concentration of SCCPs (particulate phase + gas phase) ranged from 15.12 to 66.44 ng m, with an average of 30.26 ng m in 2010, and 65.30 to 91.00 ng m, with an average of 78.15 ng m in 2016. Hexa-chlorinated dodecane and hexa-chlorinated undecane are the predominant components in the gas phase, while octa-chlorinated undecane and hepta-chlorinated tridecane are dominant in the particulate phase. In 2010, 82.57-97.16% of the total SCCPs were found in the gas phase, except that in winter, where 63.11% of the total SCCPs were in the particulate phase; the air concentrations of SCCPs in gas phase were summer > autumn > spring > winter, which was positively correlated with the change of the average ambient temperature, while it was the contrary in particulate phase. In autumn, the gas phase and the total air concentration of SCCPs in 2016 were 2.57 times more than that in 2010, while the congener group patterns of SCCPs were similar. Spearman's rank correlation analysis between the concentrations of SCCPs with meteorological parameters was conducted. The gas-particle distribution was examined through the relationship of the logarithm of the gas-particle partition coefficient with that of the subcooled vapor pressure and the octanol-air partitioning coefficient of SCCPs. Results indicated that the absorption mechanisms contributed more to the partitioning process. The exposure risk of SCCPs was evaluated, which illustrated that the estimated exposure of SCCPs via the outdoor environment in Dalian did not exceed the health concern threshold of the European risk assessment. [ABSTRACT FROM AUTHOR]

Aerosol pollution in urban environments has been recognized to be responsible for important pathologies of the cardiovascular and respiratory systems. In this perspective, great attention has been addressed to Ultra Fine Particles (UFPs < 100 nm), because they efficiently penetrate into the respiratory system and are capable of translocating from the airways into the blood circulation. This paper describes the aerosol regional doses deposited in the human respiratory system in a high-traffic urban area. The aerosol measurements were carried out on a curbside in downtown Rome, on a street characterized by a high density of autovehicular traffic. Aerosol number-size distributions were measured by means of a Fast Mobility Particle Sizer in the range from 5.6 to 560 nm with a 1 s time resolution. Dosimetry estimates were performed with the Multiple-Path Particle Dosimetry model by means of the stochastic lung model. The exposure scenario close to traffic is represented by a sequence of short-term peak exposures: about 6.6 × 10 particles are deposited hourly into the respiratory system. After 1 h of exposure in proximity of traffic, 1.29 × 10, 1.88 × 10, and 3.45 × 10 particles are deposited in the head, tracheobronchial, and alveolar regions. More than 95 % of such doses are represented by UFPs. Finally, according to the greater dose estimated, the right lung lobes are expected to be more susceptible to respiratory pathologies than the left lobes. [ABSTRACT FROM AUTHOR]

We investigate the composition of 63 C-C nonmethane hydrocarbons (NMHCs), methane (CH) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity ( k ) because of their great abundance and their relatively fast reaction rates with OH. [ABSTRACT FROM AUTHOR]

Traffic remains a major source of urban air pollution although emission regulations have led to significant reductions in exhaust emissions of new vehicles. In this work the photochemical transformation of exhaust emissions from gasoline and diesel passenger vehicles compliant with the current European 'Euro6' emission standard and operated with traditional and alternative fuels was investigated using an environmental chamber. By assessing four different engine operation conditions, we show that vehicle operation notably affects the exhaust composition and secondary aerosol formation potential. For the gasoline vehicle, secondary aerosols dominate the total particulate emissions. In contrast, we observe no substantial secondary aerosol formation for exhaust emissions of a Euro6-level diesel vehicle. High engine load operation and cold start of the gasoline vehicle led to 11–470-fold particulate mass enhancement, while for moderate driving conditions the enhancement ratio was below 2. High aerosol enhancements also led to strong increases in particle light absorption. The results underline the necessity for future directives to include the emission components leading to secondary pollution, in addition to the freshly emitted pollutants. The link observed between secondary organic aerosol (SOA) formation and gaseous aromatic hydrocarbon emissions suggests that monitoring and limiting these gaseous species can provide an indirect regulation for SOA. Additionally, ammonia released as a byproduct of the gasoline vehicle is confirmed as an important precursor for secondary aerosols. [Display omitted] • High engine load and cold start of gasoline cars generate high SOA potential. • A modern diesel vehicle caused negligible SOA formation. • High NH 3 emissions of gasoline vehicles notably contribute to secondary aerosols. • Light absorption of gasoline car PM increases during atmospheric transformation. • Aromatic gaseous emissions can be used as a proxy for SOA formation. [ABSTRACT FROM AUTHOR]

Occurrence of persistent organic pollutants (POPs) in the Polar Regions has received great concern in the past several decades due to their long-term adverse effect on biological health in such a fragile environment. However, there is still argument over their source and fate in these pristine areas. Here we attempted to use a novel approach (compound-specific isotope analysis of chlorine, CSIA-Cl) to identify the source of POPs in Antarctic air by comparison with the source area. The results showed that the relative isotope-ratio variation of Cl (δ37Cl′) values showed a large variation from − 137 to 9.04 ‰ in the gas-phase samples, and a significantly negative correlation (p < 0.01) was obtained against the logKoa values of PCBs. There were no significant correlations (p > 0.05) observed between the δ37Cl′ values and meteorological parameters except for PCB-28 which showed temperature dependence. By contrast, the δ37Cl′ values in the urban (Beijing) air ranged from − 12.8 to 2.03 ‰. The larger variation of δ37Cl′ in Antarctic air indicated evidently influence of long-range atmospheric transport (LRAT) on isotopologue fractionation of PCBs. This study may shed light on the application of CSIA-Cl for source identification of chlorinated POPs on a large scale. [Display omitted] • CSIA-Cl using HRGC/HRMS was first employed for source identification of PCBs in Antarctic air. • δ37Cl′ in Antarctic air showed larger variations compared to those in the urban air. • δ37Cl′ in Antarctic air showed a significantly negative correlation (p < 0.01) with logKoa of target PCBs. • Variation of δ37Cl′ between different sampling areas indicated influence of LRAT on atmospheric PCBs in the Antarctic. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) with aerodynamic diameters of <1 μm (PM 1), 2.5 μm (PM 2.5), and 10 μm (PM 10) were investigated and analyzed for 15 trace elements in the center of Hanoi, Vietnam during April–September 2018. The mean concentrations were 40 ± 11, 53 ± 17, and 132 ± 39 μg/m3 for PM 1 , PM 2.5 , and PM 10 , respectively, indicating that PM pollution was severe in Hanoi. During the sampling period, the PM concentrations were little affected by local meteorological conditions. The severe PM pollution in Hanoi was significantly influenced by long-range atmospheric transport from northern and northeastern regions, with higher potential source areas for PM 1. The total mean concentrations of 15 elements were 1417 ± 141, 1624 ± 159, and 2652 ± 251 ng/m3 in PM 1 , PM 2.5 , and PM 10 , respectively, with Al, Zn, K, Cr, and Ni as the most abundant elements. The particle-size distribution of PM and elements showed a distinct peak in PM 1. The metallurgy industry, coal combustion, traffic emission, biomass burning, and soil dust were identified as major contributors of elements in three-size PM. This study implies that PM 1 pollution should gain more attention regarding its level and chemical composition. [Display omitted] • PM 1 , PM 2.5 , and PM 10 were collected in Hanoi, Vietnam, and 15 elements were analyzed. • Long-range transport of PM from northern and northeastern areas was confirmed. • The particle-size distribution of PM and elements showed a distinct peak in PM 1. • Industrial activities and fossil fuel combustion were major sources of elements. • This study emphasizes the serious pollution of PM regarding its level and composition. [ABSTRACT FROM AUTHOR]

Particulate matter air pollution is a leading cause of global mortality, particularly in Asia and Africa. Addressing the high and wide-ranging air pollution levels requires ambient monitoring, but many low- and middle-income countries (LMICs) remain scarcely monitored. To address these data gaps, recent studies have utilized low-cost sensors. These sensors have varied performance, and little literature exists about sensor intercomparison in Africa. By colocating 2 QuantAQ Modulair-PM, 2 PurpleAir PA-II SD, and 16 Clarity Node-S Generation II monitors with a reference-grade Teledyne monitor in Accra, Ghana, we present the first intercomparisons of different brands of low-cost sensors in Africa, demonstrating that each type of low-cost sensor PM 2.5 is strongly correlated with reference PM 2.5 , but biased high for ambient mixture of sources found in Accra. When compared to a reference monitor, the QuantAQ Modulair-PM has the lowest mean absolute error at 3.04 μg/m 3 , followed by PurpleAir PA-II (4.54 μg/m 3 ) and Clarity Node-S (13.68 μg/m 3 ). We also compare the usage of 4 statistical or machine learning models (Multiple Linear Regression, Random Forest, Gaussian Mixture Regression, and XGBoost) to correct low-cost sensors data, and find that XGBoost performs the best in testing ( R 2 : 0.97, 0.94, 0.96; mean absolute error: 0.56, 0.80, and 0.68 μg/m 3 for PurpleAir PA-II, Clarity Node-S, and Modulair-PM, respectively), but tree-based models do not perform well when correcting data outside the range of the colocation training. Therefore, we used Gaussian Mixture Regression to correct data from the network of 17 Clarity Node-S monitors deployed around Accra, Ghana, from 2018 to 2021. We find that the network daily average PM 2.5 concentration in Accra is 23.4 μg/m 3 , which is 1.6 times the World Health Organization Daily PM 2.5 guideline of 15 μg/m 3 . While this level is lower than those seen in some larger African cities (such as Kinshasa, Democratic Republic of the Congo), mitigation strategies should be developed soon to prevent further impairment to air quality as Accra, and Ghana as a whole, rapidly grow.

The isotopic composition of nitrogen oxides (NO x = NO + NO 2 ) hold potential to trace emissions sources, as well as chemistry in the atmosphere. Passive samplers that collect NO x and NO 2 as nitrite could provide a simple and inexpensive means by which to collect samples in a variety of environments, and we report here on several methodological considerations when using Ogawa passive collectors of NO x and NO 2 for concentration analysis via colorimetric methods and isotopic analysis via the denitrifier method. Using Ogawa samplers, NO x and NO 2 were collected in Providence, RI, USA (41.8°N, 71.4°W) with exposure times of seven, fourteen, twenty-one, and twenty-eight days during summer and winter in an area dominated by vehicle emissions, particularly diesel delivery trucks. Average values were −9.7 ± 0.7‰ for δ 15 N-NO x and −8.3 ± 0.9‰ for δ 15 N-NO 2 based on duplicate seven, fourteen, twenty-one, and twenty-eight day exposures (n = 8) in summertime, and −11.9 ± 0.7‰ for δ 15 N-NO x and −6.4 ± 1.4‰ for δ 15 N-NO 2 based on seven, fourteen, twenty-one, and twenty-eight day exposures (n = 7) in wintertime. The oxygen isotopic composition (δ 18 O, Δ 17 O) was also determined with averages of: 36.3 ± 2.4‰ for δ 18 O-NO x (n = 8), 50.5 ± 3.2‰ for δ 18 O-NO 2 (n = 8), 6.2 ± 0.8‰ for Δ 17 O-NO x and 10.8 ± 0.6‰ for Δ 17 O-NO 2 (n = 4) in summer; and 38.7 ± 2.9‰ for δ 18 O-NO x and 47.4 ± 1.2‰ for δ 18 O-NO 2 (n = 7), 7.7 ± 1.5‰ for Δ 17 O-NO 2 (n = 4) and 5.3 ± 1.2‰ for Δ 17 O-NO x (n = 5), in winter. Our isotopic results differ from previous studies that utilized passive samplers and suggest specific nitrogen and oxygen isotopic signatures associated with vehicular emissions. To collect sufficient sample for multiple isotopic analyses (e.g., 10 nmol N for δ 15 N and δ 18 O; 50 nmol N for Δ 17 O) the exposure time for the samplers, even in urban areas, is at least days. This necessarily results in collection of a mixture of local emissions sources, as well as background air that can represent multiple NO x sources. Thus, passive samplers cannot be used to diagnose isotopic signatures unless only exposed to a single emissions source. The oxygen isotopic composition of nitrite (the collection analyte) results determined via the denitrifier method must be corrected in comparison to nitrate isotopic reference materials, resulting in an increase of ∼25‰. Even with this correction, the oxygen isotopic results are lower than what would be expected for ozone-dominated atmospheric chemistry in an urban area, and the oxygen isotopic results for NO x were consistently lower than that found for NO 2 . We suggest that the oxygen isotopic composition of NO and NO 2 were modified upon capture and conversion to nitrite on the passive sampler pads, and does not directly reflect abundances in the atmosphere. [ABSTRACT FROM AUTHOR]

Polycyclic Aromatic Hydrocarbons (PAHs) represent a major class of toxic pollutants because of their carcinogenic and mutagenic characteristics. People living in urban areas are regularly exposed to PAHs because of abundance of their emission sources. Within this context, this study aimed to: (i) identify and quantify the levels of ambient PAHs in an urban environment; (ii) evaluate their toxicity; and (iii) identify their sources as well as the contribution of specific sources to measured concentrations. Sixteen PAHs were identified and quantified in air samples collected from Brisbane. Principal Component Analysis – Absolute Principal Component Scores (PCA-APCS) was used in order to conduct source apportionment of the measured PAHs. Vehicular emissions, natural gas combustion, petrol emissions and evaporative/unburned fuel were the sources identified; contributing 56%, 21%, 15% and 8% of the total PAHs emissions, respectively, all of which need to be considered for any pollution control measures implemented in urban areas. [ABSTRACT FROM AUTHOR]

In this study, pine needles were used as cost-effective and reliable passive bio-monitors to concomitantly evaluate atmospheric concentrations of three classes of persistent organic pollutants, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs). The extraction of persistent organic pollutants (POPs) from needle samples was performed. Eleven PCBs, 11 OCPs, and 15 PAHs were detected and followed through time in needle samples from three sites in the Strasbourg region. The urban and rural sites were more exposed to PCBs than the suburban site. The highest concentration of PCBs was found at the urban site, but the largest number of congeners (10) was detected at the rural site. PCB 189 and 156 were the predominant congeners in the rural site and PCB 70 in the urban site. For OCPs, the rural site displayed the highest concentrations (up to 22.9 ng g) and number of compounds investigated (9). The high concentration of γ- and β-hexachlorocyclohexane (HCH) at that time in the urban site was the reason for this result. γ- and β-HCH were the two predominant compounds in all samples. The suburban and urban sites were the most exposed with PAHs with pyrene, phenanthrene, and acenaphthene being the three predominant compounds in these sites. No specific trend in terms of time was apparent for PCBs and OCPs. However, higher concentrations were detected for some compounds in the first sampling, especially for PAHs, and this is attributed to variations in meteorological conditions (e.g., temperature, wind, rain) and variable inputs from both identified and unidentified sources. [ABSTRACT FROM AUTHOR]

Humans, increasingly, manufacture their own air. In and around the three-dimensional aerial environments within and above urban regions, this manufacture of air reaches particular levels of intensity. For a species that expires without air in two or three minutes, this anthropogenic manufacture of air is of incalculable importance. Curiously, however, urban air remains remarkably neglected within the political–ecological literatures. Accordingly, this paper suggests a range of key themes, which a political ecology of urban air needs to address. These touch upon the links between global warming, urban heat-island effects and killer urban heatwaves; urban pollution crises; the paradoxes of urban pollution; horizontal movements of polluted air; the vertical politics of urban air; the construction of vertical condominium structures for elites; the vicious circles that characterise air-conditioned urbanism; heat-related deaths of workers building air-conditioned structures in increasingly hot climates; the growth of large-scale air-conditioned environments; and, finally, the manipulation of urban air through political violence. [ABSTRACT FROM PUBLISHER]

Product ion yields for a suite of hydrocarbons associated with motor vehicle exhaust including alkenes, alkanes, cycloalkanes, and aromatic compounds are reported for a PTR-MS instrument operated at an E/N ratio of 80 and 120 Td. At 120 Td many of the compounds tested underwent dissociative proton transfer reactions complicating the interpretation of the vehicle exhaust mass spectrum. However at 80 Td most aromatic and alkene compounds tested yielded M + H product ions at near 100% yield and alkyl substituted cyclohexanes and C 9 –C 12 branched alkanes yielded M-H ions as the major product ion. The PTR-MS response factors to dimethyl and trimethyl cyclohexane compounds were about a third of that expected if they reacted at the collisional rate limit with H 3 O + . Analysis of gasoline at 80 Td showed that the major peaks in the mass spectrum could be reasonably accounted for from known hydrocarbon abundance and their product ion yields, including the alkyl substituted cyclohexane compounds which yielded M-H ions at m/z 97, 111, and 125. Operation at lower E/N ratios would enable the PTR-MS to measure alkyl substituted cyclohexanes and larger alkane compounds in urban air at their M-H product ion. [ABSTRACT FROM AUTHOR]

Aerosol transport of enteric microbiota including fecal pathogens and antimicrobial resistance genes (ARGs) has been documented in a range of settings but remains poorly understood outside indoor environments. We conducted a systematic review of the peer-reviewed literature to summarize evidence on specific enteric microbiota including enteric pathogens and ARGs that have been measured in aerosol samples in urban settings where the risks of outdoor exposure and antibiotic resistance (AR) spread may be highest. Following PRISMA guidelines, we conducted a key word search for articles published within the years 1990–2020 using relevant data sources. Two authors independently conducted the keyword searches of databases and conducted primary and secondary screenings before merging results. To be included, studies contained extractable data on enteric microbes and AR in outdoor aerosols regardless of source confirmation and reported on qualitative, quantitative, or viability data on enteric microbes or AR. Qualitative analyses and metric summaries revealed that enteric microbes and AR have been consistently reported in outdoor aerosols, generally via relative abundance measures, though gaps remain preventing full understanding of the role of the aeromicrobiological pathway in the fate and transport of enteric associated outdoor aerosols. We identified remaining gaps in the evidence base including a need for broad characterization of enteric pathogens in bioaerosols beyond bacterial genera, a need for greater sampling in locations of high enteric disease risk, and a need for quantitative estimation of microbial and nucleic acid densities that may be applied to fate and transport models and in quantitative microbial risk assessment. • Aerosol transport of enteric pathogens and antimicrobial resistance (AR) in outdoor urban settings remains poorly understood. • PRISMA-adhering systematic review and qualitative analysis reveals gaps in our knowledge. • Reports of enteric or AR-associated bioaerosols are typically quantal or semi-quantitative. • There are few quantitative reports on a broad range of enteric pathogens of interest. • Less studies are conducted in cities with high enteric disease risk. [ABSTRACT FROM AUTHOR]

The organisms in aerosol microenvironments, especially densely populated urban areas, are relevant to maintenance of public health and detection of potential epidemic or biothreat agents. To examine aerosolized microorganisms in this environment, we performed sequencing on the material from an urban aerosol surveillance program. Whole metagenome sequencing was applied to DNA extracted from air filters obtained during periods from each of the four seasons. The composition of bacteria, plants, fungi, invertebrates, and viruses demonstrated distinct temporal shifts. Bacillus thuringiensis serovar kurstaki was detected in samples known to be exposed to aerosolized spores, illustrating the potential utility of this approach for identification of intentionally introduced microbial agents. Together, these data demonstrate the temporally dependent metagenomic complexity of urban aerosols and the potential of genomic analytical techniques for biosurveillance and monitoring of threats to public health. [ABSTRACT FROM AUTHOR]

Measurements of atmospheric isoprene and other selected volatile organic compounds (VOCs) were conducted in Taipei, a tropical–subtropical metropolis, to investigate diurnal variations, seasonal diversity and spatial differences in terms of the levels and sources of isoprene. Our study also investigated the responses of biogenic isoprene to both light flux and temperature in real urban settings that have a variety of plant species and traffic volumes. The robust ratio of isoprene/1,3-butadiene obtained from pure traffic emissions was used as a gauge to separate biogenic isoprene from traffic emissions. The four seasonal measurements at a typical urban site in the city showed that biogenic contributions overwhelmed their anthropogenic counterparts in summer and dominated the daytime isoprene levels in spring and autumn. Even in winter, biogenic sources still contributed a non-negligible fraction of approximately 44% to daytime isoprene. Furthermore, the concentration contour of isoprene extrapolated from the data at 38 sites throughout the city revealed that high levels of biogenic isoprene were generally a widespread phenomenon in summer in the tropical–subtropical city. A three-dimensional plot of the isoprene/1,3-butadiene ratio, ambient temperatures and radiation flux showed a temperature threshold of biogenic isoprene emissions, beyond which the biogenic contribution began to increase exponentially with enhanced ambient temperature. However, when the ambient temperature was below the threshold, there was no or negligible biogenic contribution to the ambient isoprene, regardless of the strength of the radiation flux. The temperature threshold (approximately 17–21 °C) of isoprene emissions in the tropical–subtropical city was much higher than the thresholds in cities and areas at temperate latitudes, indicating that the adaptation of vegetation to different temperature zones via isoprene emission may be characteristic. [ABSTRACT FROM AUTHOR]

PM aerosol characterization on organic tracers for biomass burning (levoglucosan and its isomers and dehydroabietic acid) was conducted within the AERTRANS project. PM filters ( N = 90) were sampled from 2010 to 2012 in busy streets in the urban centre of Madrid and Barcelona (Spain) at ground-level and at roof sites. In both urban areas, biomass burning was not expected to be an important local emission source, but regional emissions from wildfires, residential heating or biomass removal may influence the air quality in the cities. Although both areas are under influence of high solar radiation, Madrid is situated in the centre of the Iberian Peninsula, while Barcelona is located at the Mediterranean Coast and under influence of marine atmospheres. Two extraction methods were applied, i.e. Soxhlet and ASE, which showed equivalent results after GC-MS analyses. The ambient air concentrations of the organic tracers for biomass burning increased by an order of magnitude at both sites during winter compared to summer. An exception was observed during a PM event in summer 2012, when the atmosphere in Barcelona was directly affected by regional wildfire smoke and levels were four times higher as those observed in winter. Overall, there was little variation between the street and roof sites in both cities, suggesting that regional biomass burning sources influence the urban areas after atmospheric transport. Despite the different atmospheric characteristics in terms of air relative humidity, Madrid and Barcelona exhibit very similar composition and concentrations of biomass burning organic tracers. Nevertheless, levoglucosan and its isomers seem to be more suitable for source apportionment purposes than dehydroabietic acid. In both urban areas, biomass burning contributions to PM were generally low (2 %) in summer, except on the day when wildfire smoke arrive to the urban area. In the colder periods the contribution increase to around 30 %, indicating that regional biomass burning has a substantial influence on the urban air quality. [ABSTRACT FROM AUTHOR]

Low-molecular-weight aliphatic amines were measured in the ambient urban background air at the SMEAR III station (Station for Measuring Forest Ecosystem-Atmosphere Relations III) in Helsinki, Finland, from May until late August 2011. The alkyl amines measured were dimethylamine (DMA), ethylamine (EA), trimethylamine (TMA), propylamine (PA), diethylamine (DEA), butylamine (BA) and triethylamine (TEA). Of these amines, DMA + EA and TMA + PA were the most abundant, with average concentrations of 24 and 8 ppt. The ranges of weekly mean concentrations of DMA + EA and TMA + PA were

This paper focuses on the toxicity evaluation and source apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in three monitoring stations in Istanbul, Turkey. A total of 326 airborne samples were collected and analyzed for 16 PAHs and Total Suspended Particles (TSP) for the period of September 2006–December 2007. The total average PAH concentrations were 100.7±61.3, 84.6±46.7 and 25.1±13.3ngm−3 and the TSP concentrations were 101.2±53.2, 152.3±99.1, 49.8±18.6μgm−3 for URB1, URB2 and RUR stations, respectively. Benzo(a)Pyren (BaP) toxic equivalency factors to PAH concentration values were calculated indicating that the health risk of BaP and DiBenz(a,h)Anthracene (markers of traffic emissions) have the highest contribution compared to all of the other species measured at the sampling sites. In order to determine PAH sources, two different source apportionment techniques were applied to the measurements; diagnostic ratios (DR) and Positive Matrix Factorization (PMF). The results of the two applications were compatible indicating the vehicle emissions – especially diesel engines – as the major source for urban stations. [ABSTRACT FROM AUTHOR]