Odor Assessment Research Articles

Odor assessment of NH3 and volatile sulfide compounds in a full-scale municipal sludge aerobic composting plant

Methods for assessing odors in municipal sewage sludge aerobic composting plants (MSSACPs) have been ineffective. This study identified the emission amount of typical odor-producing compounds, including NH3 and volatile sulfide compounds from a full-scale MSSACP, and evaluated risks of odor emissions based on odor intensity and odor active value. Results revealed all sampling sites (i.e. sludge stacking yard, composting workshop, and screening workshop) produced serious odors, especially in the composting workshop. In the composting workshop, the amounts of DMDS (174.59 μg·dry kg−1) and DMS (71.64 μg·dry kg−1) emitted were far lower than that of NH3 (6062.56 μg·dry kg−1). However, DMDS and DMS showed a similar intensity as NH3 according to odor intensity assessment. Furthermore, both of their odor active values were higher than that of NH3. Using results from both odor intensity and odor active value were more reliable for the assessment of odors from MSSACPs.

An evaluation of a Lagrangian stochastic model for the assessment of odours

In this work, we propose and evaluate a one-particle Lagrangian stochastic model for the assessment of the concentration-fluctuation variance, which is often used to predict odour hours for example. The main challenge is to provide a suitable parameterisation for the concentration-variance dissipation time scale. While the particle mass is conserved along the particle trajectory, the concentration variance dissipates. The concentration variance in a Lagrangian particle model evolves according to the same Langevin equation used for the simulation of the turbulent dispersion resulting in a mean concentration field. The variance dissipation is taken into account via a decay term with a finite time scale. We herein discuss and compare different parameterisations of the variance-dissipation time scale against observations from a field experiment. It was found that best results are obtained prescribing the ratio between the concentration-variance dissipation time scale and the Lagrangian time scale, which depends on the travel time.

The Nose Knows… or Does it? Olfactory Reference Syndrome in Patients Presenting for Assessment of Unusual Body Odor.

Olfactory reference syndrome (ORS) is a rarely diagnosed psychiatric disorder in which individuals falsely believe that they emit an offensive body odor. This retrospective cohort study characterizes the clinical and demographic features of 54 individuals who presented to a Canadian genetics clinic for query trimethylaminuria (TMAU), an inherited disorder in which a pungent fishy odor is produced. The majority (83%) were found to have a likely diagnosis of ORS and a high rate (73.3%) of concomitant psychiatric disorders; only two patients were diagnosed with TMAU. This study highlights the genetics clinic as an unexpected and major ascertainment point for ORS, and shows that ORS can be differentiated from TMAU by age of onset (~28 years), odor characterization (refuse-related), and the presence of associated comorbid psychiatric diagnoses. There is a low diagnostic rate of ORS, attesting to the need for improved education and awareness.

Efficacy of chlorhexidine, hydrogen peroxide and tulsi extract mouthwash in reducing halitosis using spectrophotometric analysis: A randomized controlled trial.

BackgroundTo evaluate the efficacy of tulsi extract mouthrinse in reducing halitosis as compared to chlorhexidine and hydrogen peroxide mouthrinses using spectrophotometric analysis.Material and MethodsIt was a parallel, single center, double blinded randomized controlled trial of 15 days duration. A total of 300 participants were screened, out of which 45 subjects those fulfilled inclusion criteria of age range 17-35 years were included in the trial. The participants were randomly provided with tulsi, hydrogen peroxide or chlorhexidine mouthwashes (control group) to use 10 ml twice daily for 15 days. Clinical measurements were taken at baseline and 15 days using arbitrary 0-5 scale for organoleptic odor assessments, spectrophotometric analysis for Volatile Sulphide Compounds (VSCs) from saliva samples, Löe & Silness gingival index and Silness & Löe plaque index.ResultsAfter intervention, organoleptic, VSCs, gingival and plaque scores showed statistically significant decrease in all the three study groups. The mean percentage reduction in VSC and organoleptic scores was significantly greater in chlorhexidine and hydrogen peroxide groups than in the tulsi group and the mean percentage reduction in plaque and gingival scores was significantly greater in chlorhexidine group than in hydrogen peroxide and tulsi group.ConclusionsTulsi may not have the efficacy of chlorhexidine and hydrogen peroxide mouthrinses. But, Tulsi is effective in reducing halitosis, plaque and gingivitis and with its lack of side effects & cost effectiveness, can be an effective & economic tool to deal with halitosis. The spectrophotometric technique appears to be a promising method for evaluation of oral malodor. Key words:Halitosis, tulsi mouthwash, chlorhexidine, hydrogen peroxide, spectrophotometric analysis.

A mathematical model of odor dispersion from a wastewater treatment plant

Smell is an important criterion of the quality of atmospheric air. The paper looks at quantitative and qualitative methods of odor assessment and describes the method of field olfactometry. Studies were carried out on the spread of odor from the WWTP OAO OKOS in the Kaliningrad region of Russia which resulted in 817 measurements. For each measurement, the following parameters were recorded: odor strength (D/T), odor character, atmospheric pressure (mmHg), temperature (°C), relative humidity (%), wind speed (m/s), wind direction and the the point where a measurement was taken. A mathematical model is given of the dependence of odor strength on the distance to two sources s1 (m) and s2 (m) and the wind direction from a straight line passing through a given point and a source 1 — a1 or a source 2 — a2.

Stages of Development of an Electronic Nose: Correlation Results Using a Dynamic Dilution Olfactometer in Conjunction with Human Experts

The different measurement techniques employed for gas and odor assessments are usually expensive, complex and time-consuming. Moreover, using these tools individually does not provide exhaustive information about odors under analyses. Therefore, this paper presents the development of a simple and low-cost odorant data logger as the second stage of the development of an electronic nose, combined with a classical technique as dynamic threshold olfactometry. The odorant data logger allows the estimation of odor concentration and odor intensity ratio of 1-butanol vapors, and it able to measure ethanol vapors. This instrument mainly comprises two commercial MOS sensors and an ATMEGA32 microcontroller. The odorant data logger showed an appropriate response to analytes' concentrations in parts per billion, detecting lower levels than reported by the sensors' manufacturer. Calibration curves were successfully adjusted to power-law functions, and the determination coefficients, R 2 , ranged from 93 to 99 %. An olfactometric analysis for 1-butanol vapors was performed, showing a suitable R 2 of 95.8 %. In order to estimate the odor concentration with the odorant data logger, a correlation with olfactometric values was also obtained. The values of R 2 were 97.9 % and 99.4 % for the TGS 2600 and TGS 2620 sensors, respectively. In addition, the odor intensity ratio was computed, as other estimated dimension of the odor. The results of this stage of the development are promising in terms of its future usage for several applications, which will be depending mainly on the sensors array and the processing tools.

Comparison of Field Inspections and Dispersion Modelling as a Tool to Estimate Odour Emission Rates from Landfill Surfaces

This study has the final purpose to estimate the odour impact of a landfill located in Southern Italy, in the region of Puglia, by means of a field inspection that involves the direct assessment of odours in the field by trained assessors, which was carried out following the “plume method” described in the EN 16841:2016, Part 2. The primary aim of this work is to compare different methods for the estimation of Odour Emission Rates from the landfill surface in order to evaluate the method that allows to maximize the correspondence between the simulated odour impact and the outcomes of the direct assessment by field investigations. The motivation of this combined activity relies in the necessity to experimentally verify the hypotheses proposed in recent research work, which highlight the different mechanism determining odour emissions from landfill surfaces compared to the typical volatilization mechanism from passive area source, i.e. natural convection. As a consequence of this different volatilization mechanism, in the case of landfill surfaces, the recalculation of the OER as a function of the wind speed as it is done for other passive area sources may result in significant overestimation of odour impact. This study shows how the correspondence between direct field odour assessments and simulated odour impact is maximized by considering a constant SOER (Specific Odour Emission Rate) in the range of 0.07-0.25 ouE/m2/s. On the other hand, a variable SOER proportional to the square root of the wind speed results in an overestimation of about one order of magnitude of the landfill odour impact. This in turn proves the need to treat landfill surfaces as a particular type of source, requiring specific techniques for the estimation of odour emissions, which must account for the peculiarity of the mechanisms that affect landfill gas emissions into the atmosphere.

Towards a Harmonized Odour Guideline for Some Austrian Provinces

Currently some provinces in Austria attempt to set up a harmonized regulation for assessing odour nuisance. The Austrian laws do not stipulate that any nuisance is to be prevented, but only “unacceptable” nuisance. “Unacceptable” is not a scientific or medical term but needs to be interpreted in a legal context. In the new guideline different odour impact criteria (OIC) are set up with regard to the hedonic tone of odours. For each category a maximally allowed frequency is defined. Frequencies are to be assessed on the total number of hours of a year, where the computed 90th percentile within one hour is above a certain threshold concentration (e.g. 1 odour unit [ou] per m³). Such is termed an odour hour. Dispersion modelling is the major methodology for odour assessments. Unlike in Germany, no specific model is prescribed, but model developers need to prove the capability of their model to accurately simulate the 90th percentile odour concentration of an hour. For instance, the Lagrangian particle model GRAL, which is frequently used in Austria, offers a new module to compute the 90th percentile based on the work of Oettl and Ferrero (2017a). The 90th percentile is thereby a function of the three dimensional odour-concentration field and the atmospheric turbulence, thus, the model is able to take into account the effects of overlapping odour plumes, too. It could be demonstrated that modelled odour-hour frequencies using this novel approach are in very good agreement with observed odour hours assessed by field inspections following the new European standard EN 16841-1. Field inspections, therefore, may also be used for odour assessment, whenever modelling is not possible (e.g. unknown source strengths). OICs are derived upon dose-response relationships, which were established by evaluating historical citizen’s complaints using the dispersion model GRAL. Relationships between the percentage of annoyed residents and modelled odour-hour frequencies were found to be quite different for odorants having a very high potential of offensiveness and such with a moderate potential. Discontinuous odour sources are assessed by using OICs based on the 0.5th percentile evaluated for concentrations larger than 1 ou m-3. The corresponding concentration thresholds for the four distinguished hedonic tones were derived by matching the affected non-attainment areas resulting from the regulations for continuous sources with those resulting from the 0.5th percentile regulation.

Odour assessment in the vicinity of a pig-fatting farm using field inspections (EN 16841-1) and dispersion modelling

The assessment of odour annoyance varies vastly among countries even within the European Union. Using so-called odour-hour frequencies offers the distinct possibility for either applying dispersion models or field inspections, both generally assumed to be equivalent. In this study, odour-hours based on field inspections according to the European standard EN 16841-1 (2017) in the vicinity of a pig-fattening farm have been compared with modelled ones using the Lagrangian particle model GRAL, which uses odour-concentration variances for computing odour hours as recently proposed by Oettl and Ferrero (2017). Using a threshold of 1 ou m−3 (ou = odour units) for triggering odour hours in the model, as prescribed by the German guideline for odour assessment, led to reasonable agreements between the two different methodologies. It is pointed out that the individual odour sensitivity of qualified panel members, who carry out field inspections, is of crucial importance for selecting a proper odour-hour model. Statistical analysis of a large number of data stemming from dynamic olfactometry (EN 13725, 2003), that cover a wide range of odorants, suggests that the prescribed method in Germany for modelling odour hours may likely result in an overestimation, and hence, equivalence with field inspections is not given. The dataset is freely available on request.

Odor control map: Self organizing map built from electronic nose signals and integrated by different instrumental and sensorial data to obtain an assessment tool for real environmental scenarios

Olfactory nuisances are an issue of growing concern considering that people's awareness about the effect of pollution on health and environment is increasing and that the perception of odor is related to a possible warning situation. A recent review concluded that odor assessment has to be faced by an integrated multi-tool strategy. In this paper we discuss the building of a model by means of a chemometric approach based on artificial neural networks known as Self Organizing Maps. These are applied to data collected by electronic nose continuous monitoring. The Self Organizing Map output was subjected to a second level clusterization by k-means algorithm. The cluster interpretation (i.e. air types classification in terms of “malodor”/“odor free” attributes) is achieved by crosslinking data produced by different instrumental and sensorial approaches, allowing us to establish the Frequency-Intensity-Duration odor characteristics for every identified air type.In order to elucidate our approach we focused our work on a four months survey at a residential site close to an integral cycle steel plant in Trieste (Italy). Odor Control Map proved to be a promising tool to provide valuable visualization support for following the dynamic evolution of the system with time. It allowed us to, for example, identify the relationships among sensor responses in different air types; follow the changes of air types with time. identify possible malodor sources; experimentally evaluate the frequency and duration of air types classified as malodorous. Furthermore, this first application highlighted the possible method improvements that have to be tested in different real environmental scenarios to obtain more robust and refined models. Considering that different annoyances (e.g., odor, noise, presence of specific chemical compounds) can cause possible synergistic health effects, Odor Control Map is a suitable tool to integrate data deriving from different and independent analysis/monitoring to obtain a more comprehensive knowledge on complex environmental phenomena involving dwellings close to industrial plants.

Hedonic Assessment of Odors: A Comparison of Two Sensory Scales for Use with Alzheimer's Disease Patients and Elderly Individuals.

Several clinical studies concerning the olfactory function of patients with cognitive impairment have used sensory scales to investigate hedonic perception. However, no study has focused on the choice of the most appropriate sensory hedonic scale for the individuals with neurodegenerative disorders or other psychiatric diseases involving cognitive deficits. The aim of this study was to investigate the ability of patients with Alzheimer's disease (AD) to use two hedonic scales (category scale and linear scale) and compare their discriminatory capacity, repeatability, and ease of use. This should allow us to identify the most appropriate hedonic scale for patients with AD. We recruited 18 patients with mild to moderate AD, and 20 healthy volunteers matched for gender, age, smoking status, and educational level. The participants underwent a clinical assessment and hedonic evaluation of three odorants (pleasant, unpleasant, and neutral), using a five-point category scale and a 10-cm linear scale with a marked mid-point. AD patients were able to use hedonic scales as well as paired healthy elderly subjects. The linear scale performed slightly better in terms of ease of use for both patients and healthy controls and discriminatory capacity for AD patients. The results for AD patients and controls with both scales were repeatable. The linear scale may be more appropriate for AD patients pending further studies involving a larger population of patients, using several odorants.

Application of field inspections and odour observation diaries in the assessment of air quality and odour in urban areas

The choice of an odour nuisance assessment method depends on many factors, such as: the type and quantity of objects, the diversity and type of odour sources, the location of the object, the social situation and the number of complaints about odor nuisance, the type and physico-chemical parameters of the emitted gases and the conditions of dispersion of pollutants in the air. In most cases, in order to fully assess the situation and take integrated actions to reduce odour nuisance, both an instrumental/sensory analysis and a sociological research method should be used simultaneously. Such an approach enables researchers to get a real picture of the problem and develop the optimal and necessary minimization of odour impact solutions. The work presents the results of field and sociological research aimed at identifying odour sources and odour nuisance in a selected urban area located in the southern part of Poland. The studied area is complex in terms of the type and amount of odour emission sources, hence the use of several methods in the assessment of air quality was justified. The conducted research allowed the identification of emission sources and the extent of their impact on the area of the examined city and community.

Prediction of Human Responses to Dairy Odor Using an Electronic Nose and Neural Networks

Abstract. Odor emitted from dairy operations may cause negative reactions by farm neighbors. Identification and evaluation of such malodors is vital for better understanding of human response and methods for mitigating effects of odors. The human nose is a valuable tool for odor assessment, but using human panels can be costly and time-consuming, and human evaluation of odor is subjective. Sensing devices, such as an electronic nose, have been widely used to measure volatile emissions from different materials. The challenge, though, is connecting human assessment of odors with the quantitative measurements from instruments. In this work, a prediction system was designed and developed to use instruments to predict human assessment of odors from common dairy operations. The model targets are the human responses to odor samples evaluated using a general pleasantness scale ranging from -11 (extremely unpleasant) to +11 (extremely pleasant). The model inputs were the electronic nose measurements. Three different neural networks, a Levenberg-Marquardt back-propagation neural network (LMBNN), a scaled conjugate gradient back-propagation neural network (CGBNN), and a resilient back-propagation neural network (RPBNN), were applied to connect these two sources of information (human assessments and instrument measurements). The results showed that the LMBNN model can predict human assessments with accuracy as high as 78% within a 10% range and as high as 63% within a 5% range of the targets in independent validation. In addition, the LMBNN model performed with the best stability in both training and independent validation. Keywords: Animal production, Hedonic tone, Olfactometric models.

Environmental Impact Assessment of Odours from Solid Waste Landfills Located in Highly Urbanized Areas

Urbanization and the rise in the standard of living generated both a higher quantity of waste and the expansion of cities with the incorporation of solid waste landfills located originally outside. In many cities across Romania, landfills are placed very close to settlements, and in some cases even inside cities. Beside landfill activities, other companies that deal with waste sorting, recycling and treatment operates nearby. All these activities generate odorous compounds that create odour nuisance. The current study was conducted in order to evaluate the impact of a landfill located in a highly urbanized area using dynamic olfactometry with the main objective to assess the level of odour concentration and the impact on the population. Samples were taken around the landfill always from a point opposite to the wind direction. Also, in parallel with odour sampling it was determined the concentration of two main chemical specific compounds, NH3 and H2S, in order to verify the compliance with environmental legislation, and the level of VOC to establish a correlation with the odour level. Measurement results indicate a high level of odour concentration in most of the samples, a good correlation with VOC and frequent exceeded values for the specific chemical compounds. Annoyance level was also high and it was evaluated using FIDOL factors, which are Frequency, Intensity, Duration, Offensiveness and Location.

Effect of chard powder on colour and aroma formation in cooked sausages

The use of nitrate-containing vegetable powders instead of sodium nitrite in meat products requires changes in technological production parameters in order to obtain traditional organoleptic characteristics in the finished products. The aim of this work was to study the effect of chard powder on colour and aroma formation in cooked sausages. Cooked sausage samples were: control with nitrite curing mixture; type 1 sausages with chard powder and ascorbic acid; type 2 sausages with chard powder and sodium ascorbate. To transform nitrate ions contained in the vegetable chard powder to nitrite ions using a denitrifying culture, preliminary thermal treatments were used: 30 and 60 min at 40±2°C, after which the sausages were cooked until a temperature of 72±2°C was achieved. The sausages were stored for 40 days at 0-6°C. When sausage meat was initially held at 40°C for 60 min, a homogenous pink colour formed in the sausages with the vegetable powder. The indicators of lightness, redness and yellowness in cooked sausages as well as the indicators of instrumental odour assessment did not differ significantly (p>0.05). The indicators of colour stability during storage were 1.1-3.0% higher in the sausages with the chard powder compared to the control. The mass fraction of sodium nitrite in the experimental sausages was 2.0-2.2 higher than in the control (p>0.05). As a result of cooked sausage storage, the differences in the sodium nitrite content in the control and types 1 and 2 sausages were similar. During storage, the mass fraction of sodium nitrite decreased in types 1 and 2 sausages by 55.6 and 54.8%, respectively (p<0.05). Cooked sausages with the chard powder contained 2.1-2.4 times more sodium nitrate than did control sausages (p<0.05). However, all tested sausage samples complied with legislative requirements in terms of their sodium nitrite and nitrate levels.

Odour assessment methods: appropriate uses to obtain the most accurate results

Odour assessment methods: appropriate uses to obtain the most accurate results

Dynamic olfactometry and sample toxicity. a case study for a MSW incinerator odour assessment project

The study reported in this paper is focused on occupational exposure to potential toxic compounds for employees working in dynamic olfactometry, following EN 13725:2003 standard procedures.Municipal solid waste (MSW) incineration plants, typically, have authorized stack emissions for primary pollutants (like CO, NOx, particulate), for selected trace organics (polycyclic aromatic hydrocarbons (PAHs) or dioxins), metals or for total organic compounds (TOC). Odour control is limited on recommendations of good practices for the waste receiving areas and storage, generally on the air management systems.In Italy there is an increasingly number of requests, to environmental inspection authorities, Agenzia Regionale per la Protezione Ambientale (ARPA), Regional Environment Agency, to quantitatively describe possible odour annoyance effects from different industrial plants, including MSW incineration plants. Recently ARPA Piemonte has been asked to perform one odour survey for the newly incinerator for the city of Torino, that burns 500,000 t/y of MSW recovering energy through cogeneration. The plant is equipped with a pollutant's automated measuring system (AMS) to assess the compliance with the emission limit values, but not to measure odour emissions. For this reason, it is necessary to assess odour emissions as well, in order to prepare an exhaustive environmental odour scenario for the whole area.We recently presented a risk assessment approach, to evaluate non-carcinogenic and carcinogenic compounds for different sample types, based on STEL or TWA data, or EPA slope factors values respectively. It has been decide to follow this approach to define potential sample toxicity (PT), using the different risk occupational scenarios proposed, before odour concentration analysis of stack emissions samples. Using emission limit values that are set in the permit, PT has been defined. Since samples are presented to assessors in an ascending concentration series, workers exposure has been limited to acceptable levels defining the specific minimum dilution value to be used in the ARPA Piemonte olfactometric laboratory standard procedures.

Using Field Asymmetric Ion Mobility Spectrometry for Odor Assessment of Automobile Interior Components

The of the quality of odors emitted from automobile cabin interiors is an important element for the design of vehicles that meet prospective customers' expectations. Extending our previous work on machine-versus-human odor assessment for intact automobile cabin interiors, in this paper, we evaluated odors generated from individual interior parts using a human panel and field asymmetric ion mobility spectrometry (FAIMS). We used image processing techniques to extract geometric features from FAIMS dispersion fields, and built the predictive models for three odor assessment parameters (intensity, irritation, and pleasantness) by means of partial least squares regression. The best feature set was chosen by backward sequential feature selection. Using k -fold cross validation, we achieved statistically significant correlation 0.95 between human panel measured and machine olfaction predicted odor assessment scores with a sample set of 48 interior automobile parts. These results, generated using the geometric image processing methods demonstrated herein, further support the feasibility of replacing a human panel by machine olfaction for the assessment of odor quality of interior automobile parts.

Removal of Rancid-Acid Odor of Expeller-Pressed Virgin Coconut Oil by Gamma Irradiation: Evaluation by Sensory and Electronic Nose Technology

Expeller-pressed virgin coconut oil, known to have disagreeable rancid-acid odor due to the presence of octanoic acid, was subjected to gamma (γ) irradiation for removal of the same. Sensory evaluation in tandem with electronic nose (Heracles and ENOVISION) analyses established that the oil irradiated at 4.2 kGy had no rancid-acid odor (absence of octanoic acid) at the end of 28 days of storage at 23 ± 2 °C. Therefore, 4.2 kGy was established as the “appropriate irradiation dose” for removal of rancid-acid odor of virgin coconut oil. A “deodorization index” with respect to rancid-acid odor was also developed using electronic nose for confirmation of this “appropriate dose” and thereby provided possible means of preventing detrimental effects of high dose of γ-irradiation in oils. GC–MS analysis of hydrocarbons extracted from oil irradiated at 4.2 kGy by supercritical carbon dioxide extraction revealed radiolysis of octanoic acid resulting in elimination of rancid-acid odor. Further, γ-irradiation at 4.2 kGy did not affect the antioxidant potency of coconut oil rendering it a safe and healthy alternative to conventional deodorization techniques for oils. Development of methodology for assessment of rancid-acid odor of coconut oil using electronic nose has been reported for the first time in this work.

Neurobehavioral assessment of maternal odor in developing rat pups: implications for social buffering

ABSTRACTSocial support can attenuate the behavioral and stress hormone response to threat, a phenomenon called social buffering. The mother’s social buffering of the infant is one of the more robust examples; yet we understand little about the neurobiology. Using a rodent model, we explore the neurobiology of social buffering by assessing neural processing of the maternal odor, a major cue controlling social buffering in rat pups. We used pups before (postnatal day (PN) 7) and after (PN14, PN23) the functional emergence of social buffering. Pups were injected with 14C 2-deoxyglucose (2-DG) and presented with the maternal odor, a control preferred odor incapable of social buffering (acetophenone), or no odor. Brains were removed, processed for autoradiography and brain areas identified as important in adult social buffering were assessed, including the amygdala basolateral complex (Basolateral Amygdala [BLA]), medial prefrontal cortex (mPFC), and anterior cingulate cortex (ACC). Results suggest dramatic changes in the processing of maternal odor. PN7 pups show mPFC and ACC activation, although PN14 pups showed no activation of the mPFC, ACC, or BLA. All brain areas assessed were recruited by PN23. Additional analysis suggests substantial changes in functional connectivity across development. Together, these results imply complex nonlinear transitions in the neurobiology of social buffering in early life that may provide insight into the changing role of the mother in supporting social buffering.