Evaluation of Nasal Mucociliary Clearance Time in Patients with Schizophrenia

Nasal mucociliary clearance time (NMCT) is prolonged in patients with olfactory disorders. It is essential to differentially diagnose conductive and neural olfactory disorders. Here, we used the mucociliary clearance test to investigate a disease associated with neural olfactory disorders, i.e. schizophrenia. Data on age, gender, and duration of disease were collected. The study involved 56 schizophrenia patients and 56 healthy controls. There was no significant difference between the groups regarding age and gender (p = 0.459 and p = 0.768 respectively). Mean NMCT of patients with schizophrenia was 13.82 ± 3.22 min and mean NMCT of healthy controls was 10.15 ± 2.94 min. There was significant difference between the groups regarding NMCT (p < 0.001). In the patient group, there was a significant positive correlation between duration of disease, age, and NMCT (Pearson r = 0.286, p = 0.032, and Pearson r = 0.522, p < 0.001 respectively). This study has shown a prolonged NMCT in patients with schizophrenia compared to the healthy control group.

Hemoglobin and free iron influence the aroma of cooked beef by influencing the formation and release of volatiles

Cooked beef flavour is influenced by formation and release of odour-active volatiles. We hypothesised the aroma of cooked beef is affected by the concentration of heme proteins and free iron. To test our hypothesis, we spiked ground beef semitendinosus with different concentrations of hemoglobin or free iron. The patties were then grilled, and their volatile profiles were measured using gas chromatography - mass spectrometry and their sensory attributes were measured by a trained sensory panel. We found that spiking hemoglobin at 2 mg/g could suppress the release of linear aldehydes while increasing the formation of some Maillard-derived volatiles, which could potentially reduce the livery odour. The addition of free iron at 13.48 µg/g increased the livery and oxidised fat odour of cooked beef by increasing the formation of typical lipid-derived volatiles, such as 1-octen-3-ol, hexanal, and several akylfurans.

Evaluation of Nasal Mucociliary Clearance as an Indicator of Nasal Function in Obsessive-Compulsive Patients: A Cross-Sectional Study

This clinical study aimed to compare the mucociliary clearance time in patients with OCD, a disease associated with neural olfactory disorders, with a healthy control group. The mucociliary clearance time of fifty-one patients with OCD and fifty-two healthy patients (control group) was compared. The saccharin nasal mucociliary clearance test (NMCT) was applied and recorded the sociodemographic data of all participants. The NMCT was longer in OCD patients than healthy controls. There was no statistically significant difference in sociodemographic data between the groups. Our results show that olfactory transmission pathways may be affected in OCD patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03972-2.

Research on air pollutants and odour emissions from paving hot-mix asphalt with end-of-life tyre rubber

This article discusses different types of pollution from the paving process and the influence of using hot mix asphalt without and including end-of-life tyre rubber. This new composition type is one of the possible solutions to reduce the amount of used transport tyres and a new way to use less valuable raw materials. The research carried out involved analyzers applied under conditions of a mobile laboratory and handheld particle counters. Odour samples were taken using a vacuum chamber in Tedlar containers, and the level of odours was analyzed adopting the olfactometric method. Exposure to gaseous carbon, nitrogen and sulphur oxides and particulate matter up to 10 µm, fractions from 0.3 µm to 10 µm, as well as the odours emitted that cover the soil surface with the hot-mix asphalt-rubber mixture was examined. The average decrease in pollution using the asphalt-rubber mixture is about 3.8-4 % of nitrogen oxides, 10 % of particulate matter of 1.5-10, and an increase is approximately 9 % for particulate matter of 0.8-1 µm and 15 % for sulphur dioxide. The level of odour of compacted asphalt is around 2.8times lower than that in the case of level asphalt.

Assessment of dimethyl sulphide odorous emissions during coal extraction process in Coal Mine Velenje

Underground coal extraction at Coal Mine Velenje occasionally gives rise to odour complaints from local residents. This manuscript describes a robust quantification of odorous emissions of mine sources and a model-based analysis aimed to establish a better understanding of the sources, concentrations, dispersion, and possible control of odorous compounds during coal extraction process. Major odour sources during underground mining are released volatile sulphur compounds from coal seam that have characteristic malodours at extremely low concentrations at micrograms per cubic metre (μg/m3) levels. Analysis of 1028 gas samples taken over a 6-year period (2008-2013) reveals that dimethyl sulphide ((CH3)2S) is the major odour active compound present in the mine, being detected on 679 occasions throughout the mine, while hydrogen sulphide (H2S) and sulphur dioxide (SO2) were detected 5 and 26 times. Analysis of gas samples has shown that main DMS sources in the mine are coal extraction locations at longwall faces and development headings and that DMS is releasing during transport from main coal transport system. The dispersion simulations of odour sources in the mine have shown that the concentrations of DMS at median levels can represent relatively modest odour nuisance. While at peak levels, the concentration of DMS remained sufficiently high to create an odour problem both in the mine and on the surface. Overall, dispersion simulations have shown that ventilation regulation on its own is not sufficient as an odour abatement measure.

Olfactive short-term habituation in children and young people with profound intellectual and multiple disabilities

BACKGROUND

Despite its importance for learning, the existence of the habituation process and its characteristics in people with profound intellectual and multiple disabilities (PIMD) remains understudied. Habituation is, however, considered the simplest form of learning, and a significant neuroadaptive mechanism. Even though habituation occurs in all sensory modalities, the olfactory system is where it manifests itself very visibly.

AIM

This study explores the olfactory short-term habituation abilities of children and young people with PIMD.

METHOD

Twenty children and young people with PIMD (7-18 years) were presented six times successively with a 30-second habituating olfactory stimulus. The interstimulus interval was 15 s. A new odour was presented on the seventh trial. The scenario was carried out two times with two pairs of stimuli. The participants' head alignment duration on the odour was measured.

RESULTS

Seventeen participants out of 20 manifested a decline in response, which reached about 50 % between the first and sixth presentation of the habituation odour. All habituators also showed a distinctive response when exposed to a novel odour. The participants who did not habituate showed a strong, non-fluctuating response to the stimulus throughout the presentations. Three participants only habituated to one of the two habituation stimuli.

CONCLUSION AND IMPLICATIONS

The results raise theoretical, scientific, and practical issues. They question the factors explaining olfactory habituation mechanisms, namely the stimulus properties and the severity of impairment, reveal the need for points of comparison for interpreting this population's responses, and point to the consequences of stimuli repetition and or variety in therapeutic or educational settings for these individuals' learning and cognitive functioning.

Behavioural and physiological responses of Small Tail Han sheep to predators

Prey animals modify their behaviour and physiology in the presence of predators. Domestic animals differ from wild animals in having less exposure to wild predators, but whether they still retain an antipredator instinct is frequently unknown. In this study, we used domesticated Small Tail Han sheep as a model prey animal to gauge their response to the presence of predators, in the form of odours from the faeces of lion, tiger, and leopard. The faeces of male sheep and male rabbit (as a heterogeneous non-predator) were used as control. We found that the frequency and time of feeding, exploration, moving, watching, and lying down behaviours were significantly affected by predator odour, and that there was an interaction between odour sources and sex. When exposed to predator odour, sheep reduced their frequency and time of feeding, and increased their exploratory, moving, and watching behaviours. Female sheep showed greater motivation towards frequent and lengthy exploration, moving, watching, and lying down behaviours than male sheep, and less motivation towards feeding and drinking behaviours. Serum cortisol levels were lowest in response to tiger stimuli. These results illustrated that Small Tail Han sheep could recognise predator odour and adjust their behaviour to display antipredator strategies, and displayed some physiological responses, although only changing in serum cortisol could be significantly attributed to the odour of predators.

A novel integrated industrial-scale biological reactor for odor control in a sewage sludge composting facility: Performance, pollutant transformation, and bioaerosol emission mechanism

In order to remove multiple pollutants in the sewage sludge (SS) composting facility, a novel integrated industrial-scale biological reactor based on biological trickling filtration and fungal biological filtration (BTF-FBF) was developed. This study examined bioaerosol emission, odour removal, pollutant transformation mechanism, and project investment. At an inlet flow rate of 7200 m³/h, the average removal efficiencies of hydrogen sulfide (H₂S), ammonia (NH₃), and volatile organic compounds (VOCs) during the steady stage were 97.2 %, 98.9 %, and 92.2 %. The BTF-FBF separates microbial phases (bacteria and fungi) of different modules. BTF removed most hydrophilic compounds, while FBF removed hydrophobic ones. Moreover, the reactor could effectively remove pathogens or opportunistic pathogens bioaerosols, such as Escherichia coli (61.9%), Salmonella sp. (85%), and Aspergillus fumigatus (82.1%). The pollutant transformation mechanism of BTF-FBF was proposed. BTF-FBF annualized costs were 324,783 CNY/year at 15 years. In conclusion, BTF-FBF provides new insights into composting facility bioaerosol, odour, and pathogen emission control.

Hydrothermal pretreatment and compound microbial agents promoting high-quality kitchen waste compost: Superior humification degree and reduction of odour

Present study investigated the effects of hydrothermal pretreatment (HTP) and addition of compound microbial agent (CMA) on humification, odour generation and metabolism functions of bacterial communities during composting of kitchen waste (KW). Surprisingly, HTP and CMA addition treatment could promote the humification of compost and the control of odour units in contrast to the control (without HTP and CMA addition). The humic acid to fulvic acid ratio of end compost increase by 187.30 %, while humification index (HIX) increased by 18.87 %. 3D-EEM fluorescence spectroscopy of dissolved organic matter (DOM) demonstrated that it facilitated the synthesis of humified compounds and the decomposition of biodegradable compounds. Moreover, the SUVA₂₅₄, SUVA₂₈₀ and E₂₅₃/E₂₀₃ increased by 118.6 %, 115.25 % and 42.11 % after HTP and CMA addition indicating an increase in aromatic carbon abundance. VFAs had the higher degradation rate (84.91 %) than other treatments (57.46-77.72 %). Meanwhile, the main contributor to the malodorous odour was isovaleric acid, followed by butyric acid and acetic acid during composting. Mantel test indicated that the humification degree was significantly influenced by environmental parameters (temperature, pH, etc.) and metabolic products (HA, DOC and VFAs). Metagenomic analysis indicated that the biodegradation processes at the thermophilic stage were controlled mainly through genes involved in microbial metabolism. HTP and CMA addition was an eco-friendly and efficient strategy to reduce odour emission and improve the compost quality.

Systematic review of topical interventions for the management of odour in patients with chronic or malignant fungating wounds

Chronic wounds adversely affect the quality of life of individuals and odour is a well-recognised associated factor. Odour can affect sleep, well-being, social interactions, diet and potentially wound healing. This systematic review aims to examine the effectiveness of topical interventions in the management of odour associated with chronic and malignant fungating wounds. A systematic review guided by PRISMA recommendations of randomised controlled trials where odour intensity/odour is the primary outcome was undertaken. Inclusion criteria were adults (18 years and over) with chronic venous, arterial, diabetic or pressure ulcers or with malignant fungating wounds where odour has been managed through topical application of pharmacological/non-pharmacological agents. Searches were conducted in CENTRAL, CINAHL, EMBASE, MEDLINE, Scopus, and Web of Science. Eligibility screening, risk of bias assessment and data extraction was completed by authors working independently. Searches retrieved 171 titles and abstracts (157 post de-duplication). Thirteen studies were retained for full text review of which five (n = 137 individuals) examining the following treatments remained: metronidazole (n = 4), silver (n = 1). Meta-analysis was not possible but individual studies suggest improved outcomes (i.e., reduced odour) using metronidazole. Treatment options to manage wound odour are limited and hampered by lack of clinical trials, small sample sizes, and absence of standardised outcomes and consistent measurement. Whereas metronidazole and silver may have a role in controlling wound odour, robust and well-designed interventions with rigorous procedures and standardised odour outcomes are necessary to evaluate their contribution.

Odour impact assessment using kinetics and optimization: case studies on removal of multiple volatile organo-sulphur compounds from sewage wastewater using porous functional materials

Expanding industries and booming population have led to the increase in the installation of wastewater and sewer systems, even in close proximity to residential areas. Emissions from these installations particularly volatile organo-sulphur compounds (VOSCs) such as methyl mercaptan (CH₃SH), ethyl mercaptan (C₂H₅SH), dimethyl sulphide (CH₃SCH₃) and carbon disulphide (CS₂) are a nuisance to people even when present in small concentration. Strategies for removal involve addition of chemicals or other chemical processes which are generally expensive. Biofilters, on the other hand, consume large amount of energy and wash waters. Hence keeping commercialization in mind, it is important to develop a strategy which would be cost-effective and at the same time be effective to remove most of the odorous compounds present in these systems. In the present research work, granular activated carbons (GAC) are functionalized with alkali solution to improve the adsorption capacity. Liquid phase batch adsorption is performed with GAC and various functionalized activated carbons (FACs) with the help of raw sewage water from a local sewage water treatment plant. Concentration of odour was evaluated by two methods-olfactometry-based analysis for sensory measurement and GCMS-based analysis for analytical estimation of a specific odorous compound. The adsorption capacities of the functionalized GACs are higher primarily because of complex formation at the surface of modified GACs. Pseudo-second-order kinetic model agreed well with experimental results with the rate constant being 0.0191 mg/l min and 0.0153 mg/l min for methyl and ethyl mercaptan adsorption onto FAC-NH₃. Boyd's film diffusion along with rate kinetic model supported that chemical adsorption forms the rate-limiting step. Response surface methodology (RSM) was used to optimize the removal of VOSCs with respect to different process parameters like adsorbent amount and time. The olfactometry removal of overall odour was also optimized taking 6 factors in the Box Behnken design. Variance of analysis results indicated that all the models displayed considerable goodness of fit with R² values close to 1. Methyl mercaptan turned out to be the highest contributor to the overall odour as confirmed both from experimental and optimization study. The optimized olfactometry odour removal (77.4%) along with CH₃SH removal (80.34%), C₂H₅SH removal (59.16%), CH₃SCH₃ removal (63.21%) and CS₂ removal (71.95%) was found at optimum process conditions, with amount of adsorbent of 10.29 g, adsorption time of 2.92 h. This result indicates that methyl mercaptan (CH₃SH) is the highest odour contributing component out of the studied VOSCs. The results show promising potential for the use of activated carbon as an adsorbent for removal of odorous compounds from STPs.

Warmed-over flavour profiles, microbial changes, shelf-life and check-all-that-apply sensory analysis of cooked minced pork treated with varying levels of Moringa oleifera leaf and root powder

This study investigated warmed-over flavour profiles, microbial changes, shelf-life and sensory characteristics of minced cooked pork treated with Moringa oleifera (M. oleifera) root and leaf powder during refrigerated storage at 4 °C. A total of 8 treatments (control = no antioxidant; 0.5ML = 0.5% M. oleifera leaf; 1ML = 1% M. oleifera leaf; 0.5MR = 0.5 % M. oleifera root; 1MR = 1% M. oleifera root; 0.5MLR = 0.5% M. oleifera leaf and root mixed; 1MLR = 1% M. oleifera leaf and root mixed; BHT = 0.02% butylated hydroxytoluene) were evaluated. The minimum inhibitory concentration (MIC) of the plant extracts against the test bacteria was determined using the serial dilution in 96 well microtiter plates technique. Warmed-over flavour profiles were determined using the test for carbonyls assay where hexanal was used as a marker for warmed-over flavour. The check-all-that-apply sensory tool was used to characterise minced cooked pork treated with different antioxidants according to warmed-over flavour taste and odour intensities. The results showed that the antibacterial assay of the extracts exhibited a broad-spectrum of activity against the tested bacteria. The leaf extracts demonstrated better activity against both gram-negative and gram-positive bacteria, with most of the MICs at less than 1 mg/mL, while the root performed better against gram-negative bacteria compared to gram-positive bacteria. There was a significant rapid increase in the warmed-over flavour profiles of the control compared to the M. oleifera and BHT treated pork. The pork samples which had M. oleifera leaf, root, and their combination at inclusion levels of 1% and 0.5% displayed lower warmed-over flavour profiles that fell in the range (1.0–1.46 mg hexanal/100g fat) throughout the storage period. Consumer sensory evaluation revealed that pork samples treated with the highest inclusion level (1%) of the M. oleifera leaf powder received the lowest consumer rating scores for appearance. Based on these results, adding M. oleifera leaf and root powder can decrease warmed-over flavour development and improve the shelf-life of processed pork. Furthermore, the incorporation of M. oleifera root powder can potentially be more acceptable to consumers because of its colour compared to the leaf, which gives the product a green colour that may not be pleasant for some consumers. This suggests that the inclusion of the root powder at 1% may be well accepted for consumption by consumers.

Odours as context cues of emotional memories - The role of semantic relatedness

Odours constitute effective context cues, facilitating memory retrieval. Identifying factors which modulate the effectiveness of olfactory context cues can advance the understanding of processes underlying this effect. We hypothesized that the interplay of subjective stress and semantic relatedness between the odour and the learning material would modulate the effectiveness of an olfactory context cue. We further explored the effect of the odorant Hedione, which is a ligand for a putative human pheromone receptor (VN1R1). To this end, 120 participants watched a video of a stressful episode in which visual objects were present, that were either manipulated in the video (central objects) or not (peripheral objects). Participants rated their subjective stress afterwards. After 24 h, recognition and spatial memory of the objects in the video were tested. Ambient during encoding and recall was an odour related to the episode, an unrelated odour, Hedione or no odour. As a result, we observed a narrowing of recognition memory with increased subjective stress elicited by the video - but only if a semantically related odour was ambient. Moreover, higher subjective stress predicted enhanced spatial memory in the no odour condition, but not in presence of a semantically related or unrelated odour. When exposed to Hedione, higher subjective stress predicted impaired recognition and spatial memory of peripheral objects. Our findings stress the importance of considering semantic relatedness between the olfactory context and the encoded episode when applying odours as context cues for emotional or stressful memories.

Topical odour management in burn patients

Preventing microbial colonization or infections that cause offensive smells may lead to odor reduction. As both anaerobic and aerobic bacteria cause the release of malodor from wounds, the most direct way of avoiding or eliminating wound odor is to prevent or eradicate the responsible infection through the debridement of necrotic tissues. However, some burn patients with malodorous wounds are unable to undergo debridement due to systemic conditions, especially in the acute stage. Moreover, the optimal drug doses and dressings to ensure the efficacy and cost-effectiveness of odorous burn wound management is unclear. The purpose of this commentary is to outline the odor management options available for burn patients, focusing on topical strategies. Numerous potential therapies for treating odorous wounds after burn injuries are suggested.

First characterization of toxic alkaloids and volatile organic compounds (VOCs) in the cryptic dendrobatid Silverstoneia punctiventris

Background

Poison frogs are known for the outstanding diversity of alkaloid-based chemical defences with promising therapeutic applications. However, current knowledge about chemical defences in Dendrobatoidea superfamily has two sources of bias. First, cryptic, brown-colored species have been neglected in comparison to those conspicuously colored, and second, there has been little interest in characterizing metabolites other than alkaloids mediating defensive functions. In an effort to contribute to fill the gap of knowledge about cryptic species and broadening the spectrum of compounds analyzed we have applied head-space solid phase microextraction coupled to gas chromatography and mass spectrometry (HS-SPME/GC-MS) for extracting amphibian alkaloids and volatile organic compounds (VOCs) from Silverstoneia punctiventris.

Results

Using the skin from 8 specimens in 4 biological replicates we have found 33 different compounds. Twenty of them were classified as VOCs into 15 chemical classes including alkanes, alcohols, carbonyl compounds, methylpyridines, benzothiazoles, N-alkylpyrrolidines, pyrazines, and sesquiterpenoids, some of which were previously reported as repellents, defence compounds or defence pheromones in other organisms, and as sex pheromones in a treefrog. Interestingly, six of the remaining compounds were identified as alkaloids previously reported in other toxic/unpalatable dendrobatid frogs.

Conclusions

This is the first report of alkaloids and VOCs found in the Silverstoneia genus, which has been assumed for decades as non-chemically defended. This study establishes HS-SPME/GC-MS as a new application for a simultaneous approach to amphibian alkaloids and VOCs in poison frogs while opens up new research questions to assess the co-occurrence of both type of compounds and to investigate the evolutionary significance of a defence gradient that includes olfactory avoidance, unpalatability, and toxicity in dendrobatids. In addition, our results show that amphibian alkaloids could have a dual function (olfactory at distance, taste by contact) never explored before neither in Silverstonaeia nor in any other dendrobatid species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-021-00420-1.

Development of a chimeric odour blend for attracting gravid malaria vectors

Background

Odour-based tools targeting gravid malaria vectors may complement existing intervention strategies. Anopheles arabiensis are attracted to, and stimulated to oviposit by, natural and synthetic odours of wild and domesticated grasses associated with mosquito breeding sites. While such synthetic odour lures may be used for vector control, these may have limited efficacy when placed in direct competition with the natural source. In this study, workflows developed for plant-feeding pests was used to design and evaluate a chimeric odour blend based on shared attractive compounds found in domesticated grass odours.

Methods

Variants of a synthetic odour blend, composed of shared bioactive compounds previously identified in domesticated grasses, was evaluated sequentially in a two-choice olfactometer to identify a ratio-optimized attractive blend for malaria vectors. During this process, blends with ratios that were significantly more attractive than the previously identified synthetic rice blend were compared to determine which was most attractive in the two-choice olfactometer. To determine whether all volatile components of the most attractive blend were necessary for maximal attraction, subtractive assays were then conducted, in which individual components were removed for the most attractive blend, to define the final composition of the chimeric blend. Binary logistic regression models were used to determine significance in all two-choice assays. The chimeric blend was then assessed under field conditions in malaria endemic villages in Ethiopia, to assess the effect of dose, trap type, and placement relative to ground level. Field data were analyzed both descriptively and using a Welch-corrected t-test.

Results

A ratio-optimized chimeric blend was identified that significantly attracted gravid An. arabiensis under laboratory conditions. In the field, trap captures of An. arabiensis and Anopheles pharoensis were dependent on the presence of the lure, trap type (CDC, BG Sentinel and Suna traps), placement relevant to ground level, with low release rates generally luring more mosquitoes.

Conclusions

The workflow designed for the development of chimeric lures provides an innovative strategy to target odour-mediated behaviours. The chimeric lure identified here can be used in existing trapping systems, and be customized to increase sustainability, in line with goals of the Global Vector Control Response Group.

Spatial information from the odour environment in mammalian olfaction

The sense of smell is an essential modality for many species, in particular nocturnal and crepuscular mammals, to gather information about their environment. Olfactory cues provide information over a large range of distances, allowing behaviours ranging from simple detection and recognition of objects, to tracking trails and navigating using odour plumes from afar. In this review, we discuss the features of the natural olfactory environment and provide a brief overview of how odour information can be sampled and might be represented and processed by the mammalian olfactory system. Finally, we discuss recent behavioural approaches that address how mammals extract spatial information from the environment in three different contexts: odour trail tracking, odour plume tracking and, more general, olfactory-guided navigation. Recent technological developments have seen the spatiotemporal aspect of mammalian olfaction gain significant attention, and we discuss both the promising aspects of rapidly developing paradigms and stimulus control technologies as well as their limitations. We conclude that, while still in its beginnings, research on the odour environment offers an entry point into understanding the mechanisms how mammals extract information about space.

Odour impact assessment by considering short-term ambient concentrations: A multi-model and two-site comparison

Short-term events are one of the specific aspects that differentiate odour nuisance problems from conventional air quality pollutants. Atmospheric dispersion modelling has been considered the gold standard to realise odour impact assessments and to calculate separation distances. Most of these models provide predictions of concentrations of a pollutant in ambient air on an hourly basis. Even when the hourly mean odour concentration is lower than the perception threshold, concentration peaks above the threshold may occur during this period. The constant peak-to-mean factor is nowadays the most widespread method for evaluating short-term concentrations from the long-term ones. Different approaches have been proposed in the scientific literature to consider non-constant peak-to-mean factors. Two prominent approaches to do so are the i) variable peak-to-mean factor which considers the distance from the source and atmospheric stability and the ii) concentration-variance transport. In this sense, the aim of this work is to compare the results of three different freely available dispersion models (namely, CALPUFF, LAPMOD and GRAL), which implement three distinct ways to evaluate the short-term concentration values. Two sites, one in Austria and the other in Italy, were selected for the investigation. Dispersion model results were compared and discussed both in terms of long-term (hourly) concentrations and short-term. An important outcome of this work is that the dispersion models provided more equivalent results for hourly mean concentrations, in particular in the far-field. On the contrary, the method to evaluate short-term concentrations can deliver disparate results, thereby revealing a potential risk of poor assessment conclusions. The utilistion of a multiangle methodological approach (dispersion models, study site locations, algorithms to incorporate short-term concentrations) allowed providing useful information for future studies and policymaking in this field. Accordingly, our findings call for awareness on how the use of a particular dispersion model and its sub-hourly peak calculation method can affect odour impact assessment conclusions and compliance demonstrations.

Mitigation of diffuse CH4 and H2S emissions from the liquid phase of UASB-based sewage treatment plants: challenges, techniques, and perspectives

Upflow anaerobic sludge blanket (UASB) reactors are considered to be a sustainable and well-established technology for sewage treatment in warm climate countries. However, gases dissolved in the effluent of these reactors, CH₄ and H₂S in some instances, are a major drawback. These dissolved gases can be emitted into the atmosphere downstream of the anaerobic reactors, resulting in odour nuisance and, in the case of H₂S, corrosion, while in the case of CH₄, increasing greenhouse gas emissions with a significant loss of potentially recoverable energy. In this sense, this study aims to provide a critical review of the recent efforts to control CH₄ and H₂S dissolved in UASB reactor effluents, with a focus on the different available techniques. Different desorption techniques have been tested for the removal/recovery of dissolved CH₄ and H₂S: diffused aeration, simplified desorption chamber, packed desorption chamber, closed downflow hanging sponge reactor, membrane contactor, and vacuum desorption chamber. Other recent publications addressing the oxidation of these compounds in biological posttreatments with simultaneous nitrification/denitrification of ammonia were also discussed. Additionally, the rationale of CH₄ recovery was determined by energy balance and carbon footprint approaches, and the H₂S removal was examined by modelling its emission and atmospheric dispersion.

Characterising the sensory quality and volatile aroma profile of clean-label sucrose reduced sponge cakes

The sensory and aroma quality of 30% (w/w) sucrose reduced sponge cakes incorporating clean-label replacers were investigated. The sensory quality of the reformulated sponge cakes varied, with those containing apple pomace powder (APP) showing the greatest difference to the control (SC100). Volatile profiles mainly differed in relation to compounds derived from the Maillard reaction, caramelisation and lipid oxidation. Thrity six aroma active volatile compounds were identified in the SC100, APP and oligofructose (OLIGO) sponge cakes by olfactometry. Furfural 'spicy bready' contributed most to the overall aroma of all samples, with factor dilution values differing the most for heptanal 'fatty cake crust', methional 'potato damp', and 2,5-dimethylpyrazine 'cake crust, nutty'. This study provides an in-depth insight into the impact of sugar reduction reformulation on the sensory perception of sponge cakes and demonstrates how this approach can be used to improve the sensory perception of reduced sucrose sponge cakes.

Importance of 2,4,6-Trichloroanisole (TCA) as an odorant in the emissions from anaerobically stabilized dewatered biosolids

Odours from stabilized biosolids after anaerobic digestion of wastewater sludge can cause local community impact. Apart from the well-known odorants such as sulfur compounds, contributions from other volatile organic compounds (VOCs) to nuisance odours is limited. The presence of compounds with low odour detection thresholds (ODTs) at low concentrations, can present challenges for analytical identification. Thirty-six biosolids samples were taken after anaerobic stabilisation and dewatering at a wastewater treatment plant, Sydney, Australia. Biosolid cake samples were stored outside in loosely covered trays under aerobic conditions, however without interactions with soil microorganisms as it would be in reality. All biosolids cake samples were analysed over a period of 35 days. Emissions were collected onto Tenax TA sorbent tubes using a U.S. EPA flux hood method at storage days 1, 3, 7, 10, 14, 21 and 35. Gas chromatography (GC) coupled with mass spectrometer detector (MSD) and an olfactory detection port (ODP) was used to identify a musty/moldy/earthy type odorant in the biosolids emissions as 2,4,6-trichloroanisole (TCA). Measured odour intensities, classified on a scale from 1 to 4, and odour characters were specified by three ODP assessors. TCA was identified in all biosolid cake emissions. The measured odour intensities of the TCA did not significantly alter as the biosolids were aged, however varied between biosolids cakes. Due to its odour intensity, 85% frequency of detection and its low ODT, which is orders of magnitudes lower than sulfur compounds, TCA should be considered as a potential odorant of concern in biosolids emissions.

Sniffing animals as a diagnostic tool in infectious diseases

BACKGROUND

Scents and odours characterize some microbes when grown in the laboratory, and experienced clinicians can diagnose patients with some infectious diseases based on their smell. Animal sniffing is an innate behaviour, and animals' olfactory acuity is used for detecting people, weapons, bombs, narcotics and food.

OBJECTIVES

We briefly summarized current knowledge regarding the use of sniffing animals to diagnose some infectious diseases and the potential use of scent-based diagnostic instruments in microbiology.

SOURCES

Information was sought through PubMed and extracted from peer-reviewed literature published between January 2000 and September 2019 and from reliable online news. The search terms 'odour', 'scent', 'bacteria', 'diagnostics', 'tuberculosis', 'malaria' and 'volatile compounds' were used.

CONTENT

Four major areas of using sniffing animals are summarized. Dogs have been used to reliably detect stool associated with toxigenic Clostridioides difficile and for surveillance. Dogs showed high sensitivity and moderate specificity for detecting urinary tract infections in comparison to culture, especially for Escherichia coli. African giant pouched rats showed superiority for diagnosing tuberculosis over microscopy, but inferiority to culture/molecular methods. Several approaches for detecting malaria by analysing host skin odour or exhaled breath have been explored successfully. Some microbial infections produce specific volatile organic compounds (VOCs), which can be analysed by spectrometry, metabolomics or other analytical approaches to replace animal sniffing.

IMPLICATIONS

The results of sniffing animal studies are fascinating, and animal sniffing can provide intermediate diagnostic solutions for some infectious diseases. Lack of reproducibility, and cost of animal training and housing are major drawbacks for wider implementation of sniffing animals. The ultimate goal is to understand the biological background of this animal ability and to characterize the specific VOCs that animals are recognizing. VOC identification, improvement of odour sampling methods and development of point-of-care instruments could allow implementation of scent-based tests for major human pathogens.

Dispersion modeling of odour, gases, and respirable dust using AERMOD for poultry and dairy barns in the Canadian Prairies

For determining setback distances considering multiple air pollutants, a comprehensive study was conducted to simulate the atmospheric dispersion of odour, ammonia (NH₃), hydrogen sulfide (H₂S), and respirable dust using an US EPA air dispersion model AERMOD for a commercial dairy, broiler, and cage-layer barn in the Canadian Prairies. The simulation was conducted using five years of meteorological data. Setback distances were determined with the input of varying monthly emission rates of all four air pollutants and odour impact criteria specifically developed for all three odour sources. Results showed the layer barn had the greatest odour impact area (maximum 3023 m for an annual average odour concentration of 0.01 OU m^-3) followed by the broiler and dairy barns. Due to the prevailing south wind for all three barns, odour traveled farthest in the north. Using the suggested odour impact criteria by the Government of Saskatchewan defined for all odour sources, maximum setback distances were decreasing from 1941 to 641 m for the layer barn and from 980 to 320 m for the broiler barn along with the increasing of odour concentration (OC) thresholds (1-6 OU m^-3), all in the north direction. While for the dairy barn, setback distances were determined only under an OC limit of 1 OU m^-3; maximum 205 m in the north and minimum 171 m in the south. Using the newly developed odour impact criteria specifically for the three odour sources, maximum setback distance of 558 m in the north was determined for the layer barn under an odour threshold of 9 OU m^-3. Additionally, the results suggest the use of odour impact criteria for determining setback distance rather than using gas/respirable threshold limits set in ambient air quality standards as the former always requires much greater setback distances than the latter.

Filling in sewage sludge biodrying gaps: Greenhouse gases, volatile organic compounds and odour emissions

In the present work, a complete study of the sewage sludge (SS) biodrying technology was conducted at bench-scale, aiming at assessing its performance and providing a valuable insight into the different gaseous emission patterns found for greenhouse gases (GHG) and odorant pollutants. As process key parameters, temperature, specific airflow, dynamic respiration index, final moisture content and Lower Calorific Value (LCV) were evaluated. At the end of the biodrying, a product with a 35.9% moisture content and a LCV of 7.1 MJ·kg^-1product was obtained. GHGs emission factor was 28.22 kgCO_2eq per Mg of initial mass of dry matter in the SS (DM₀-SS). During the biodrying process, maximum odour concentration measured was 3043 ou·m^-3 and the estimated odour emission factor of the biological treatment was 3.10E + 07 ou per Mg DM₀-SS. Finally, VOCs were completely identified and quantified. The most abundant VOCs found in the biodrying gaseous emissions were terpenes, sulphur-compounds and ketones.

Contaminants migrating from crossed-linked polyethylene pipes and their effect on drinking water odour

The formation potential of contaminants diffusing from cross-linked polyethylene (PE-X) pipes and their impact on the odour of drinking water was determined. Three types of PE-X material, Pe-Xa, PE-Xb and PE-Xc, were extensively assessed by performing migration tests following EN 1420 and EN 12873-1. Migration waters were analysed for their threshold odour number (TON). The same samples were investigated by two gas chromatography-mass spectrometry methods: screening and olfactometry. Most of the PE-X materials failed the German regulation of TON <2 for cold water and TON ≤4 for warm water. PE-Xb material caused the strongest odour and also released the highest amount of contaminants. Metilox, 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, 3,5-di-tert-butyl-4-hydroxybenzaldehyde and 2,6-di-tert-butyl-p-benzoquinone (2,6-DtBQ) were the most often detected substances leaching from the tested plastic materials. However, no odour was perceived for most of these substances. Methyl tert-butyl ether (MtBE) and 2-tert-butylphenol are believed to contribute to the sensory problem in the migration water among other substances such as tert-amyl methyl ether, 2,2,2,5-tetramethyltetrahydrofuran, toluene or xylene. In total ten specific descriptions characterized the odour of the individual contaminants: ethereal, fresh, solvent, sweet, fruity, floral, unsavoury, pungent, aromatic and chemical.

Establishing the extent of odour plumes and buffers for waste handling facilities

Odour is a significant challenge for regulators of waste handling facilities due to the increasing demand for land surrounding these facilities. Many sites, including landfills, composters, abattoirs and rendering plants, that were once isolated are now close to residential areas. In some cases, this has contributed to odour impacts on residents living in those areas. Authorities have been reliant on odour modelling and odour design criteria to predict or estimate the distance at which impacts are likely to occur on sensitive land use. However, it is increasingly evident that reliance on modelling tools, and the estimated odour emission rates used in modelling, are not reflecting ground level observations. Environment Protection Authority Victoria ("EPA") conducted six in-field odour monitoring campaigns between 2007 and 2017. We studied these six campaigns to understand the extent of odour plumes from waste handling facilities. The campaigns used odour surveillance methodology developed by EPA. They consisted of in-field odour assessments around common waste handling facilities such as composters, landfills, abattoirs and rendering plants. We used the results of surveillance in conjunction with reverse trajectory plotting to estimate the typical extent and frequency of odour plumes as a function of distance. The study showed that the application of consistent in-field odour assessment methodologies improved understanding of odour plumes, and hence increases the options available to manage impacts.

Odorous emission reduction from a waste landfill with an optimal protection system based on fuzzy logic

Effective landfill management and operation require an accurate evaluation of the occurrence and extent of odour emission events, which are among the main causes of resident complaints and concerns, in particular in densely urbanised areas. This paper proposes a fuzzy optimal protection system (FOPS) based on fuzzy logic to manage odour production from a municipal solid waste (MSW) landfill. The case study is a MSW landfill in an old quarry site located 6 km north-west of Naples city centre (Italy). The aim is to reduce the odour nuisance in the area surrounding the landfill where there are several sensitive receptors. FOPS is based on logical relationships between local atmospheric dynamics, number and intensity of odour pollution events detected by certain fixed receptors and odour emission rate via an optimal fuzzy approach. Such system allows to start, in real time, established mitigation actions required to further reduce the odorous emissions from the landfill itself (e.g. spraying of perfumed substances and activation of extraction wells), especially when weather conditions might not be favourable and cause by causing a higher odour perception. The fuzzy system was coupled with the air pollutant transport software CALPUFF to simulate the odour dispersion in the considered area taking into account both different odour emission rates and local weather conditions. FOPS results show that this approach can be very useful as, by measuring the odour concentrations, a significant reduction of the odour exceedances over the thresholds fixed, to minimise the olfactory harassment, was observed in the whole area studied.

Trickling filter technology for biotreatment of nitrogenous compounds emitted in exhaust gases from fishmeal plants

Odour emissions are a major environmental issue associated with fishmeal production. Laboratory-scale biotrickling filters (BTFs) were inoculated with microbial consortia derived from sewage sludge, with the goal to study the biotreatment of low-loads of methylamines and ammonia that are main components of odorous exhaust gases produced by fishmeal processing plants. A BTF packed with ceramic rings was subjected to a real fishmeal plant emission containing trimethylamine (TMA), dimethylamine (DMA) and monomethylamine (MMA). The highest elimination capacities (ECs) obtained were 372 mg TMA m^-3 h^-1, 5.518 mg DMA m^-3 h^-1 and 1.038 mg MMA m^-3 h^-1, with maximal removal efficiencies of 92% (TMA), 83% (DMA) and 95% (MMA) after 30 days operation. In a different experiment, a polyurethane foam packing was employed to treat ammonia (NH₃) at low inlet loads, reaching an EC of 47.19 mg N m^-3 h^-1 with 99.8% efficiency (inlet load of 47.27 mg N m^-3 h^-1). Likewise, the microbial community of the polyurethane-associated biofilm was diverse and stable during operation. These results suggested that elimination of volatile amino-compounds using BTFs inoculated with a methylotrophic microbial consortium holds potential for odour removal. In addition, sequencing analysis of 16S rDNA gene fragments allowed the identification of heterotrophic ammonia-oxidizing bacteria that are promising candidates to effectively maintain ammonia elimination in a biotreatment operation of nitrogenous compounds present in exhaust gases from fishmeal facilities.

Understanding the effect of ventilation, intermittent pumping and seasonality in hydrogen sulfide and methane concentrations in a coastal sewerage system

Gas pollutants emitted during wastewater transport contribute to atmospheric pollution, aggravated risks for utility workers, infrastructure corrosion, and odour nuisance. Field studies have shown that is difficult to effectively obtain reliable correlations between in-sewer air movement and gas pollutant concentrations. This study aimed at investigating the influence of different ventilation and operating conditions in H₂S and CH₄ horizontal and vertical movement in a section of a gravity sewer, downstream of a pumping station. Relevant liquid and gas phase quality parameters were monitored, and significant H₂S concentrations were measured (with lower contents of CH₄). Results evidenced that headspace temperature and ventilation played a key effect when analysing H₂S and CH₄ dynamics. Setups with a similar content of sulfide and chemical oxygen demand resulted in different H₂S and CH₄ headspace concentrations. It was also observed that an increase in ventilation resulted in a decrease of average headspace relative humidity of over 70%, with clear implications in corrosion potential estimates. Another interesting observation was that the wastewater drag induced by intermittent pumping, in absence of ingassing, originated pressure differences of up to 0.2 Pa m^-1 between studied manholes. This differential originated a wave pattern of gas moving upstream and downstream, thus resulting in several gas peaks per pumping event, at the same sections. In addition, in confined setups, full mixing was not observed along the manholes.

Formation of odorous and hazardous by-products from the chlorination of amino acids

The formation of odorous aldehydes and N-chloraldimines, and also nitriles, which are potentially hazardous to human health, was investigated in studies of the chlorination of amino acids (AAs) in both operational drinking water treatment plants and laboratory-based experiments. In the drinking water treatment plants studied, the concentration of total free AAs did not significantly change after treatment, even though good removal of DOC was observed. However, free AAs still contributed less than 3% of total nitrogen in the treated drinking waters, and no aldehydes, N-chloraldimines or nitriles of interest were detected in the treated waters, presumably due to the low concentrations of the precursor AAs in these water samples. Laboratory formation potential experiments showed that carboxylic acids can form from the degradation of aldehydes and nitriles. Volatile carboxylic acids could result in odour issues and some carboxylic acids may be of potential health concern. Therefore, carboxylic acids should also be considered as potential by-products of interest in distribution systems with long contact times of ≥ 7days. A higher proportion of nitrile formation, and promotion of carboxylic acid formation, was observed when the chlorine to AA ratio was greater than 4 compared to when this ratio was 2.8, indicating that the Cl:AA ratio is an important factor in DBP formation pathways. This suggests that results from laboratory formation studies undertaken at these low Cl:AA ratios cannot be directly applied to 'real' water systems, which typically have Cl:AA ratios that are orders of magnitude higher than 4. Laboratory formation potential experiments also showed that the short-term rate of formation of aldehydes and N-chloraldimines was reduced in the presence of ammonia, although formation over longer timescales (e.g. 7 days) was not significantly different between chlorination and chloramination experiments. Therefore, the use of chloramination instead of chlorination does not appear to reduce the formation of these by-products from AAs.

Host Decoy Trap (HDT) with cattle odour is highly effective for collection of exophagic malaria vectors

BACKGROUND

As currently implemented, malaria vector surveillance in sub-Saharan Africa targets endophagic and endophilic mosquitoes, leaving exophagic (outdoor blood-feeding) mosquitoes underrepresented. We evaluated the recently developed host decoy trap (HDT) and compared it to the gold standard, human landing catch (HLC), in a 3 × 3 Latin square study design outdoors in western Kenya. HLCs are considered to represent the natural range of Anopheles biting-behaviour compared to other sampling tools, and therefore, in principle, provide the most reliable profile of the biting population transmitting malaria. The HDT incorporates the main host stimuli that attract blood-meal seeking mosquitoes and can be baited with the odours of live hosts.

RESULTS

Numbers and species diversity of trapped mosquitoes varied significantly between HLCs and HDTs baited with human (HDT-H) or cattle (HDT-C) odour, revealing important differences in behaviour of Anopheles species. In the main study in Kisian, the HDT-C collected a nightly mean of 43.2 (95% CI: 26.7-69.8) Anopheles, compared to 5.8 (95% CI: 4.1-8.2) in HLC, while HDT-H collected 0.97 (95% CI: 0.4-2.1), significantly fewer than the HLC. Significantly higher proportions of An. arabiensis were caught in HDT-Cs (0.94 ± 0.01; SE) and HDT-Hs (0.76 ± 0.09; SE) than in HLCs (0.45 ± 0.05; SE) per trapping night. The proportion of An. gambiae (s.s.) was highest in HLC (0.55 ± 0.05; SE) followed by HDT-H (0.20 ± 0.09; SE) and least in HDT-C (0.06 ± 0.01; SE). An unbaited HDT placed beside locales where cattle are usually corralled overnight caught mostly An. arabiensis with proportions of 0.97 ± 0.02 and 0.80 ± 0.2 relative to the total anopheline catch in the presence and absence of cattle, respectively. A mean of 10.4 (95% CI: 2.0-55.0) Anopheles/night were trapped near cattle, compared to 0.4 (95% CI: 0.1-1.7) in unbaited HDT away from hosts.

CONCLUSIONS

The capability of HDTs to combine host odours, heat and visual stimuli to simulate a host provides the basis of a system to sample human- and cattle-biting mosquitoes. HDT-C is particularly effective for collecting An. arabiensis outdoors. The HDT offers the prospect of a system to monitor and potentially control An. arabiensis and other outdoor-biting mosquitoes more effectively.

Pilot-scale biofiltration at a materials recovery facility: The impact on bioaerosol control

This study investigated the performance of four pilot-scale biofilters for the removal of bioaerosols from waste airstreams in a materials recovery facility (MRF) based in Leeds, UK. A six-stage Andersen sampler was used to measure the concentrations of four groups of bioaerosols (Aspergillus fumigatus, total fungi, total mesophilic bacteria and Gram negative bacteria) in the airstream before and after passing through the biofilters over a period of 11 months. The biofilters achieved average removal efficiency (RE) of 70% (35 to 97%) for A. fumigatus, 71% (35 to 94%) for total fungi, 68% (47 to 86%) for total mesophilic bacteria and 50% (-4 to 85%) for Gram negative bacteria, provided that the inlet concentration was high (10³-10⁵ cfu m^-3), which is the case for most waste treatment facilities. The performance was highly variable at low inlet concentration with some cases showing an increase in outlet concentrations, suggesting that biofilters had the potential to be net emitters of bioaerosols. The gas phase residence time did not appear to have any statistically significant impact on bioaerosol removal efficiency. Particle size distribution varied between the inlet and outlet air, with the outlet having a greater proportion of smaller sized particles that represent a greater human health risk as they can penetrate deep into the respiratory system where gaseous exchange occurs. However, the outlet concentrations were low and would further be diluted by wind in full scale applications. In conclusion, this study shows that biofilters designed and operated for odour degradation can also achieve significant bioaerosol control in waste gas.

Alternating pure oxygen and air cycles for the biostabilization of unsorted fraction of municipal solid waste

Biostabilisation is a process of treating the unsorted fraction of municipal solid waste (UFMSW) mechanically pre-treated. Although concepts such as circular economy would seem to limit biostabilization, several authors have recently described the advantages of biostabilization in regions where recycling systems are inadequate. In this perspective, the development of new MBT technologies is of considerable importance. The objective of the study was to evaluate the effects of the use of alternating air and oxygen cycles on the treated waste stability as well as on the quality of leachate and process gaseous emissions. Two Herhof biocells were prepared for this purpose. One implemented the conventional process and the other the "Air + O₂" process. The biostabilization of the inlet UFMSW (3965 ± 1965 mgO₂/kgVS/h) resulted in a final product with a dynamic respirometric index almost equal in both processes. The mass balance indicated that of the 400 tons representing the input waste, 37.57% were biostabilized waste, 0.29% leachate and 62.14% CO₂ and odours. However, the biostabilized waste was lower than that of the conventional process (equal to 40.18%). The Air + O₂ system resulted in a shorter duration, increased production of leachate (although characterized by higher quality) and process gaseous emissions quality. The energy balance (20.3 kJ/kg per input waste) and cost analysis (80.0 €/ton per input waste) showed values equal or better to those of the conventional system. By contrast, weakness was in the O₂ diffusion system. Although a life cycle analysis is necessary, the results highlighted the feasibility of the proposal especially for emergency situations.

Odours and incontinence: What does the nose know?

The fear of producing malodours that can be detected by others is a daily cause of anxiety for millions of people with incontinence. For many, the risk-whether real or imagined-that leaked waste products will be detectable by odour is sufficiently concerning to result in limitations on many types of activities. However, worry about personal odours can sensitise our olfactory system and cause us to be more aware of odours that may otherwise not be perceptible. In addition, heightened olfactory attention can often lead to odour misattributions, such as when we erroneously identify our body as the source of an odour that may simply be present in the environment. Odours produced by our bodies (endogenous odours) do enjoy a greater access to emotional brain centers and are processed faster than general odours. Here we provide examples from both everyday life and laboratory studies to explain how and why the olfactory system is unique among our sensory systems and how this knowledge can provide insights to our concerns about smell and incontinence and inform the development of products and solutions for incontinence.

Human exposure to hydrogen sulphide concentrations near wastewater treatment plants

The hydrogen sulphide (H₂S) levels from wastewater treatment plants (WWTPs) in Curitiba, Brazil have been quantified for the first time. H₂S generated by anaerobic decomposition of organic matter in WWTPs is a cause for concern because it is an air pollutant, which can cause eye and respiratory irritation, headaches, and nausea. Considering the requirement for WWTPs in all communities, it is necessary to assess the concentrations and effects of gases such as H₂S on populations living and/or working near WWTPs. The primary objective of this study was to evaluate the indoor and outdoor concentration of H₂S in the neighbourhood of two WWTPs located in Curitiba, as well as its human health impacts. Between August 2013 and March 2014 eight sampling campaigns were performed using passive samplers and the analyses were carried out by spectrophotometry, presenting mean concentrations ranging from 0.14 to 32μgm^-3. Eleven points at WWTP-A reported H₂S average concentrations above the WHO recommendation of 10μgm^-3, and 15 points above the US EPA guideline of 2μgm^-3. At WWTP-B the H₂S concentration was above US EPA guideline at all the sampling points. The I/O ratio on the different sampling sites showed accumulation of indoor H₂S in some instances and result in exacerbating the exposure of the residents. The highest H₂S concentrations were recorded during the summer in houses located closest to the sewage treatment stations, and towards the main wind direction, showing the importance of these factors when planning a WWTP. Lifetime risk assessments of hydrogen sulphide exposure showed a significant non-carcinogenic adverse health risk for local residents and workers, especially those close to anaerobic WWTPs. The data indicated that WWTPs operated under these conditions should be recognized as a significant air pollution source, putting local populations at risk.

Survey of the effect of odour impact on communities

In the context of environmental malodour, surveys are valuable as they allow for the relatively detailed analysis of multiple factors pertaining to odour perception and subsequent reaction. However, the causes for an individual to experience odour impact while a neighbour will not are still not understood. The goal of this current survey design was to consolidate varying research paths for surveys within the environmental odour research space. This survey investigated the area of effect for wastewater treatment plants by using stratified random sampling techniques that radiated from the industrial areas. Additionally, this survey provided a "non-alerted" response to environmental malodour that represents a step forward for ecological validity. We found a small number of items relating to odour annoyance and home ownership that can be used in order to predict odour impact for individual community members. However, we also did not find any relationship with odour impact and perceived control. This survey design and analysis reconciles the varied approaches towards community surveys administered in prior literature, as well as providing information to improve future community engagement policies.

Characterisation of volatile organic compounds (VOCs) released by the composting of different waste matrices

The complaints arising from the problem of odorants released by composting plants may impede the construction of new composting facilities, preclude the proper activity of existing facilities or even lead to their closure, with negative implications for waste management and local economy. Improving the knowledge on VOC emissions from composting processes is of particular importance since different VOCs imply different odour impacts. To this purpose, three different organic matrices were studied in this work: dewatered sewage sludge (M1), digested organic fraction of municipal solid waste (M2) and untreated food waste (M3). The three matrices were aerobically biodegraded in a bench-scale bioreactor simulating composting conditions. A homemade device sampled the process air from each treatment at defined time intervals. The samples were analysed for VOC detection. The information on the concentrations of the detected VOCs was combined with the VOC-specific odour thresholds to estimate the relative weight of each biodegraded matrix in terms of odour impact. When the odour formation was at its maximum, the waste gas from the composting of M3 showed a total odour concentration about 60 and 15,000 times higher than those resulting from the composting of M1 and M2, respectively. Ethyl isovalerate showed the highest contribution to the total odour concentration (>99%). Terpenes (α-pinene, β-pinene, p-cymene and limonene) were abundantly present in M2 and M3, while sulphides (dimethyl sulphide and dimethyl disulphide) were the dominant components of M1.

Distribution and sensorial relevance of volatile organic compounds emitted throughout wastewater biosolids processing

A diverse range of volatile organic compounds (VOCs) are emitted from wastewater biosolids processing. Odorous emissions are predominately made up of volatile sulfur compounds (VSCs) which are typically the only odorants measured. However, a range of VOCs are known to contribute to malodours yet previous studies often overlook the contribution of VOCs in comparison with VSCs. This study aims to evaluate how emissions are affected by different biosolids processing configurations, and if any non-sulfur VOCs should be included in odour measurement and management. Non-sulfur VOCs emitted from biosolids throughout six wastewater treatment plants in the Sydney, Australia region were measured at six locations on average twice each week over 2-3weeks at each site. Variations in types of VOCs emitted throughout and between the sites were assigned to differences in WWTP processing configurations, plant operation and variations in industrial and municipal flows to the sewer network, referred to as sewer catchments. The presence of VOCs is likely due to biotic generation as well as industrial or residential additions to the sewer network. The dewatered and stored biosolids samples had the highest levels of VOC emissions. Sensorially important odorants were p-cresol and butanoic acid, based on the frequency of detection and odour activity values. Other compounds with a high risk of nuisance impacts were trimethylamine, indole and phenol emitted from the dewatered and stored biosolids, and volatile fatty acids from the anaerobic digester inlet and outlet at one particular site. The findings show that non-sulfur VOCs should be added to odorant monitoring campaigns at WWTPs. Identification of VOCs as sensorially important odorants opens opportunities for the more efficient management of nuisance odours, through targeted odour control or process improvement.

Volatile compounds and odour characteristics of seven species of dehydrated edible seaweeds

The volatile fraction of dehydrated edible seaweeds belonging to seven species (Himanthalia elongata, Laminaria ochroleuca, Palmaria palmata, Porphyra umbilicalis, Saccharina latissima, Ulva lactuca and Undaria pinnatifida) was analyzed by gas chromatography-mass spectrometry, after solid-phase microextraction of samples. Thirty-six hydrocarbons, 34 ketones, 28 aldehydes, 23 alcohols, 8 carboxylic acids, 6 halogenated compounds, 4 furans, 3 esters, 2 sulphur compounds, 2 pyrazines, 1 pyridine and 1 amine were detected among the 151 volatile compounds found in seaweeds. There were significant differences between seaweed species for all the volatile compounds. Hydrocarbons reached their highest levels in U. pinnatifida, ketones in P. umbilicalis, aldehydes in P. palmata and P. umbilicalis, alcohols in P. umbilicalis, carboxylic acids in S. latissima, and halogenated compounds in L. ochroleuca and S. latissima. Sensory analysis revealed that P. palmata, U. lactuca and H. elongata were the seaweeds showing the most potent seafood odour and seaweed odour characteristics.

Vapor intrusion risk of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME) and ethyl tert-butyl ether (ETBE): A modeling study

Vapor intrusion of synthetic fuel additives represents a critical yet still neglected problem at sites contaminated by petroleum fuel releases. This study used an advanced numerical model to investigate the vapor intrusion potential of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and ethyl tert-butyl ether (ETBE). Simulated indoor air concentration of these compounds can exceed USEPA indoor air screening level for MTBE (110μg/m³). Our results also reveal that MTBE has much higher chance to cause vapor intrusion problems than TAME and ETBE. This study supports the statements made by USEPA in the Petroleum Vapor Intrusion (PVI) Guidance that the vertical screening criteria for petroleum hydrocarbons may not provide sufficient protectiveness for fuel additives, and ether oxygenates in particular. In addition to adverse impacts on human health, ether oxygenate vapor intrusion may also cause aesthetic problems (i.e., odour and flavour). Overall, this study points out that ether oxygenates can cause vapor intrusion problems. We recommend that USEPA consider including the field measurement data of synthetic fuel additives in the existing PVI database and possibly revising the PVI Guidance as necessary.

Continuous measurement of atmospheric reduced sulphur compounds as key tracers between odour complaints and source apportionment

Odour complaints are frequent nowadays, particularly nearby industrial facilities emitting odorous compounds. Among all compounds susceptible of causing odour annoyance, reduced sulphur compounds (RSC) were studied, due to their unpleasant odour and low odour threshold. RSC ambient air mixing ratios, meteorological conditions and population complaints were analysed in an area of complex topography in order to identify their potential sources. Mixing ratios of three compounds, dimethyl sulphide (DMS), carbon disulphide (CDS) and dimethyl disulphide (DMDS), were continuously monitored using an online gas chromatograph coupled with a mass spectrometer detector (GC-MSD), which was placed in a mobile air quality monitoring unit. Measurement campaigns were performed during 2012 and 2013 for periods of 7-25 days in an urban area (four campaigns, N = 1368) and an urban area surrounded by industrial activities (three campaigns, N = 564). During such campaigns, RSC mixing ratios were frequently above their odour thresholds, which did not always involve citizen complaints. Average RSC ambient air mixing ratios tended to be lower in the urban area (DMS 0.06-0.33, CDS 0.05-0.10, DMDS 0.07-0.30 μg m^-3) than in the industry surrounded one (DMS 0.30-2.39, 0.05-0.18, DMDS 0.09-0.62 μg m^-3). The DMS/DMDS mixing ratio was frequently above 1, being a paper mill one of the main sources of RSC in the area. DMS/DMDS ratios below 1 were also recorded, suggesting a waste treatment plant as the RSC source or older air masses coming from the paper mill.

A review of odour impact criteria in selected countries around the world

Exposure to environmental odour can result in annoyance, health effects and depreciation of property values. Therefore, many jurisdictions classify odour as an atmospheric pollutant and regulate emissions and/or impacts from odour generating activities at a national, state or municipal level. In this work, a critical review of odour regulations in selected jurisdictions of 28 countries is presented. Individual approaches were identified as: comparing ambient air odour concentration and individual chemicals statistics against impact criteria (maximum impact standard); using fixed and variable separation distances (separation distance standard); maximum emission rate for mixtures of odorants and individual chemical species (maximum emission standard); number of complaints received or annoyance level determined via community surveys (maximum annoyance standard); and requiring use of best available technologies (BAT) to minimize odour emissions (technology standard). The comparison of model-predicted odour concentration statistics against odour impact criteria (OIC) is identified as one of the most common tools used by regulators to evaluate the risk of odour impacts in planning stage assessments and is also used to inform assessment of odour impacts of existing facilities. Special emphasis is given to summarizing OIC (concentration percentile and threshold) and the manner in which they are applied. The way short term odour peak to model time-step mean (peak-to-mean) effects is also captured. Furthermore, the fundamentals of odorant properties, dimensions of nuisance odour, odour sampling and analysis methods and dispersion modelling guidance are provided. Common elements of mature and effective odour regulation frameworks are identified and an integrated multi-tool strategy is recommended.

Performance, litter quality and gaseous odour emissions of broilers fed phytase supplemented diets

The effect of graded levels of phytase on performance, bone characteristics, excreta/litter quality and odorant emissions was examined using 720 Ross 308 male d-old broilers. A 2 × 4 factorial arrangement of treatments was employed with 6 replicates of 15 birds per pen. Factors were: diets-positive and negative control (PC, NC); phytase – 0, 500, 1,000, 1,500 FTU/kg. The PC was formulated to meet the 2014 Ross 308 nutrient specifications, whereas the NC was formulated with lower Ca (−1.4 g/kg), available P (−1.5 g/kg), Na (−0.3 g/kg), dLys (−0.2 g/kg) and MEn (−0.28 MJ/kg) equivalent to nutrient matrix values for 500 FTU/kg phytase in the starter, grower and finisher periods (i.e., downspec diet). On d 24, phytase decreased FCR by 1.6, 4.3 and 4.6 points at inclusion levels of 500, 1,000 and 1,500 FTU/kg, respectively (P < 0.01) across all diets. Phytase by diet interactions on BW gain were observed on d 24 and 35 (P < 0.01). The effect of phytase was much more pronounced in the NC diet as compared with the PC diet. On d 24, phytase increased BW gain by 37, 55 and 68 g in the PC and 127, 233 and 173 g in the NC at 500, 1,000 and 1,500 FTU/kg, respectively. Diet by phytase interactions were also observed for tibia ash, litter quality and water to feed intake ratio (P < 0.01) with higher phytase effect in NC as compared with PC. Neither diet nor phytase impacted excreta moisture content on d 18 or 21 (P > 0.05). Solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS) analysis of gaseous emissions on d 39 indicated no difference in the emission of alcohols, aldehydes, ketones, volatile fatty acids and phenols between treatments (P > 0.05). The results indicate that phytase has greater benefits when formulated using nutrient matrix values as compared with adding it over the top in an already nutrient sufficient diet. The later method would be expected to increase feed costs without concomitant performance benefits.

Behavioural responses of Pacific salmon to chemical disturbance cues during the spawning migration

Many fish that are exposed to a threat release disturbance cues, which are chemicals that alert conspecifics to the presence of the threat. The release of disturbance cues has been well demonstrated in various species of laboratory-reared fish. Migratory fish species often exhibit increased cortisol levels and are exposed to numerous stressors during their migrations, which could trigger the release of disturbance cues. We tested the responses of wild migrating sockeye salmon (Oncorhynchus nerka) and pink salmon (O. gorbuscha) to the odours of disturbed and undisturbed conspecifics to determine whether these fish release disturbance cues following exposure to a simulated stressor. Furthermore, we tested the responses of sockeye salmon to water-borne cortisol, following evidence from past studies that this chemical is excreted through the gills of stressed fish, and speculation that endogenous correlates of stress might function as disturbance cues. We found that sockeye salmon avoid the odour of disturbed conspecifics, whereas pink salmon do not. Avoidance occurred in both female and male sockeye salmon, and was associated with an increase in plasma cortisol levels in females, but not in males. We also found no behavioural response to water-borne cortisol, which suggests this chemical does not act as an exogenous disturbance cue in sockeye salmon. Avoidance of disturbed conspecifics could limit exposure to risks during the sockeye salmon spawning migration, but could also delay the rate of migration and thereby accrue reproductive costs.

Effect of reuterin-producing Lactobacillus reuteri coupled with glycerol on the volatile fraction, odour and aroma of semi-hard ewe milk cheese

The effect of the biopreservation system formed by Lactobacillus reuteri INIA P572, a reuterin-producing strain, and glycerol (required for reuterin production), on the volatile fraction, aroma and odour of industrial sized semi-hard ewe milk cheese (Castellano type) was investigated over a 3-month ripening period. The volatile compounds were extracted and analyzed by SPME-GC-MS and cheese odour and aroma profiles were studied by descriptive sensory analysis. Control cheese was made only with a mesophilic starter and experimental cheeses with L. reuteri were made with and without glycerol. The addition of L. reuteri INIA P572 to milk enhanced the formation of six volatile compounds. Despite the changes in the volatile compounds profile, the use of L. reuteri INIA P572 did not noticeably affect the sensory characteristics of cheese. On the other hand, the addition of L. reuteri INIA P572 coupled with 30mM glycerol enhanced the formation of twelve volatile compounds, but decreased the formation of five ones. The use of the biopreservation system did not affect overall odour and aroma quality of cheese although it resulted in a significant decrease of the odour intensity scores. In addition, this cheese received significant higher scores for "cheesy" aroma and significant lower scores for the aroma attributes "milky", "caramel" and "yogurt-like". The first two axes of a principal component analysis (PCA) performed for selected volatile compounds and sensory characteristics, accounting for 75% of the variability between cheeses, separated cheeses made with L. reuteri INIA P572 and glycerol from the rest of cheeses, and also differentiated control cheese from cheeses made with L. reuteri INIA P572 from day 60 onward. Our results showed that the reuterin-producing L. reuteri INIA P572 strain, when coupled with glycerol, may be a suitable biopreservation system to use in cheese without affecting odour and aroma quality.

Olfactory Specific Satiety depends on degree of association between odour and food

The pleasantness of a food odour decreases when that food is eaten to satiety or even smelled for a brief period (Olfactory Specific Satiety, OSS), which suggests that odours signal food variety and encourage approach behaviour toward novel foods. In the study here, we aimed to extend this theory to understand the consequence of manipulating the food consumed and its degree of association to the evaluated odour. We also wished to clarify if these effects related to individual sensitivity to the target odour. In the study here, participants (n = 94) rated the pleasantness of a food odour (isoamyl acetate) and then consumed confectionary that had either Low or High association to that odour or a No food control. This was followed by final pleasantness ratings for the odour and a threshold sensitivity test. Results revealed that in line with OSS, pleasantness decreased in the High association group only. This effect was not dependent on any differences in sensitivity to the target odour. These findings are consistent with OSS, and that this effect likely depends on activation of brain areas related to odour hedonics rather than the degree to which the odour is detected.

Analysis of odour compounds from scented consumer products using gas chromatography-mass spectrometry and gas chromatography-olfactometry

Scented consumer products are being bought in increasing amounts and gaining more popularity. There is, however, relatively little information available about their ingredients, emissions and allergenic potential. Frequently, a mixture of different fragrance substances and not solely an individual substance contributes to the overall desired smell. The aim of this study was to investigate the odorous volatile organic compounds (OVOCs) in consumer products containing fragrances. Over 44 products were selected: various scented candles, printing products with different scent types and other products types particularly meant to be used indoors. Measurements were carried out in a desiccator. Air samples were collected on thermal desorption tubes to determine the released fragrance substances by means of gas chromatography-mass spectrometry (GC-MS). Moreover, gas chromatography-olfactometry (GC-O) was used to obtain sensory data and to ensure no important odorant was overlooked. Using both methods it was possible to distinguish between odour active and inactive compounds and subsequently to identify almost 300 different odorants across all scented products. Besides the advantage of differentiation, as the human nose is a very sensitive detector, GC-O was found to be a useful tool for detecting traces and chosen target compounds. One focus in this study lay on the 26 EU-regulated fragrance allergens to prove their relevance in scented consumer goods. In total, 18 of them were identified, with at least one substance being present in almost every product. Benzyl alcohol, cinnamaldehyde, citronellol, eugenol, linalool and limonene were the prevalently detected allergens. Particularly linalool and limonene were observed in over 50% of the products. In addition, eugenol appeared to be one of the most frequently detected compounds in trace-level concentrations in the candle emissions.

Dietary composition affects odour emissions from meat chickens

Abatement of odour emissions has become an important consideration to agricultural industries, including poultry production. The link between diet and odour emissions was studied in two experiments using Ross 308 male meat chickens reared in specially designed chambers in a climate controlled room. In the first experiment, two treatments were compared using three replicates of two birds per chamber. Two wheat-soy based treatment diets were formulated with or without canola seed, an ingredient rich in sulfur amino acids. Treatment 1 (T1) had 13.39 MJ/kg ME (as fed) and used 60 g/kg canola seed without corn while Treatment 2 (T2) contained 12.90 MJ/kg ME (as fed) and used 150 g/kg corn without canola seed. In the second experiment, birds were assigned to three dietary treatments of five replicates with five birds per replicate (chamber). The basal starter, grower and finisher diets in the control group (SBM group) contained soybean meal in the range of 227-291 g/kg (as fed) as the main protein source. The other treatments (CM and MBM groups) contained either high levels of canola meal (174-190 g/kg) or meat meal (74-110 g/kg) at the expense of soybean meal. In both experiments, diets were isocaloric, isonitrogenous and contained similar digestible amino acid contents as per 2007 Aviagen Ross 308 guidelines. Emissions of odour were measured using Fourier transform infrared (FTIR) spectroscopy. In both experiments, major odorous compounds detected included 2,3-butanedione (diacetyl), 2-butanone, dimethyl disulfide, methyl mercaptan, ethyl mercaptan, 2-butanol, 3-methyl-butanal, phenol and m-cresol. In the first experiment, T1 (with canola seed) produced higher concentration of methyl mercaptan (P < 0.05) and lower diacetyl (P < 0.01) than T2. In the second experiment, methyl mercaptan emission was higher in SBM group (P = 0.01) and total elemental sulfur were higher in SBM and CM groups up to day 24 (P < 0.01). Results of these experiments indicated a direct link between diet and odour emissions from meat chickens.

Higher energy efficient homes are associated with increased risk of doctor diagnosed asthma in a UK subpopulation

INTRODUCTION

The United Kingdom (UK) has one of the highest prevalence of asthma in the world, which represents a significant economic and societal burden. Reduced ventilation resulting from increased energy efficiency measures acts as a modifier for mould contamination and risk of allergic diseases. To our knowledge no previous study has combined detailed asset management property and health data together to assess the impact of household energy efficiency (using the UK Government's Standard Assessment Procedure) on asthma outcomes in an adult population residing in social housing.

METHODS

Postal questionnaires were sent to 3867 social housing properties to collect demographic, health and environmental information on all occupants. Detailed property data, residency periods, indices of multiple deprivation (IMD) and household energy efficiency ratings were also investigated. Logistic regression was used to calculate odds ratios and confidence intervals while allowing for clustering of individuals coming from the same location.

RESULTS

Eighteen percent of our target social housing population were recruited into our study. Adults had a mean age of 59 (SD±17.3) years and there was a higher percentage of female (59%) and single occupancy (58%) respondents. Housing demographic characteristics were representative of the target homes. A unit increase in household Standard Assessment Procedure (SAP) rating was associated with a 2% increased risk of current asthma, with the greatest risk in homes with SAP >71. We assessed exposure to mould and found that the presence of a mouldy/musty odour was associated with a two-fold increased risk of asthma (OR 2.2 95%; CI 1.3-3.8). A unit increase in SAP led to a 4-5% reduction in the risk of visible mould growth and a mouldy/musty odour.

DISCUSSION

In contrast to previous research, we report that residing in energy efficient homes may increase the risk of adult asthma. We report that mould contamination increased the risk of asthma, which is in agreement with existing knowledge. Exposure to mould contamination could not fully explain the association between increased energy efficiency and asthma. Our findings may be explained by increased energy efficiency combined with the provision of inadequate heating, ventilation, and increased concentrations of other biological, chemical and physical contaminants. This is likely to be modified by a complex interaction between occupant behaviours and changes to the built environment. Our findings may also be confounded by our response rate, demographic and behavioural differences between those residing in low versus high energy efficient homes, and use of self-reported exposures and outcomes.

CONCLUSION

Energy efficiency may increase the risk of current adult asthma in a population residing in social housing. This association was not significantly modified by the presence of visible mould growth, although further research is needed to investigate the interaction between other demographic and housing characteristic risk factors, especially the impact of fuel poverty on indoor exposures and health outcomes.

STUDY IMPLICATIONS

A multidisciplinary approach is required to assess the interaction between energy efficiency measures and fuel poverty behaviours on health outcomes prior to the delivery of physical interventions aimed at improving the built environment. Policy incentives are required to address fuel poverty issues alongside measures to achieve SAP ratings of 71 or greater, which must be delivered with the provision of adequate heating and ventilation strategies to minimise indoor dampness. Changes in the built environment without changes in behaviour of domicile residents may lead to negative health outcomes.