Odor Assessment Research Articles

Odour assessment of school toilets in Gauteng, South Africa – before and after bioremediation

Sanitation in school toilets is often considered peripheral to the academic project, yet has a significant impact on productivity and the school experience. A micro-study, pilot project to quantify the perception of odours in toilets at two schools in Gauteng Province, South Africa, using olfactory tests, reveals the presence of select odour-forming compounds. The compounds of butyric acid, indole, p-cresol and dimethyl trisulfide, reconstituted faecal odour and stale urine odour were presented to staff at the two schools in the form of ‘Sniffin’ Sticks’. All the odours were identified in the toilets at levels of unbearable in School A which has a septic tank system, and tolerable in School B which uses a flush system, during the pre-test. A post-test was conducted after an effective bioremediation treatment product was applied. We found that 100% of the participants noted a marked improvement in the odours in the toilets after the treatments were combined with efficient cleaning regimes.

Prediction of human odour assessments based on hedonic tone method using instrument measurements and multi-sensor data fusion integrated neural networks

A Cyranose 320 (eNose) and a Fast Gas Chromatograph (CG) analyser (zNose™) were used to measure the headspace odour of solid samples from dairy operations. The measurements of both sensors were trained by Levenberg–Marquardt Back-propagation Neural Network (LMBNN) to match human assessments. A trained human panel was used to assess the odours based on hedonic tone method and provide the model targets. A multi-sensor data fusion approach was developed and applied to integrate the eNose and zNose readings for higher predictive accuracy compared to each sensor alone. Principle Component Analysis, Forward Selection, and Gamma Test were applied to reduce the model input dimensions. Measurement fusion models and information fusion model approaches were applied. The information fusion prediction models were shown to be more accurate than all other models, including single instrument models. The information fusion model based on eNose with Gamma Test data reduction + zNose showed the best results of all cases in validation mean square error (0.34 odour units), R value (0.92), probability of the prediction falling within 10% of the target (96%), and probability of the prediction falling within 5% of the target (63%).

Odour assessment of school toilets in Gauteng, South Africa – before and after bioremediation

Sanitation in school toilets is often considered peripheral to the academic project, yet has a significant impact on productivity and the school experience. A micro-study, pilot project to quantify the perception of odours in toilets at two schools in Gauteng Province, South Africa, using olfactory tests, reveals the presence of select odour-forming compounds. The compounds of butyric acid, indole, p-cresol and dimethyl trisulfide, reconstituted faecal odour and stale urine odour were presented to staff at the two schools in the form of ‘Sniffin’ Sticks’. All the odours were identified in the toilets at levels of unbearable in School A which has a septic tank system, and tolerable in School B which uses a flush system, during the pre-test. A post-test was conducted after an effective bioremediation treatment product was applied. We found that 100% of the participants noted a marked improvement in the odours in the toilets after the treatments were combined with efficient cleaning regimes.

Assessment, monitoring, and regulation of odors of any origin in industrial enterprises

Virtually any enterprise in the food and chemical industries, as well as in treatment facilities, has waste with a distinctive unpleasant smell. Elimination of odors is becoming an urgent task for ensuring safety and labor protection at enterprises, as well as public health protection. Olga Malykh, junior research associate at the company "Odor Laboratory N 1", speaks about the experience of smell research at enterprises, the possibilities of olfactometric research, and modern methods and equipment.

Evaluation of smell disorders after radiotherapy in patients with laryngeal neoplasm

Abstract BACKGROUND. Smell disorders may be classified in quantitative and qualitative. The literature shows that the main causes of odour disorders, both qualitative and quantitative, are due to aging, viral infections and tumors of the upper respiratory tract, craniocerebral trauma, neurodegenerative diseases of the nervous system, drug use or exposure to various toxic substances. Total laryngectomy and oncologic treatment causes smell disorders. OBJECTIVE. The aim of this study is to evaluate the aspects related to the patient’s smell disorders after total laryngectomy, during the oncological treatment represented by radiotherapy. MATERIAL AND METHODS. A prospective observational study was performed on a group of 52 patients, over a period of one year (2016-2017), who benefited from total laryngectomy and who underwent oncological treatment, represented by radiotherapy. Patients were evaluated before starting radiotherapy and during radiotherapy sessions. All patients underwent quantitative and qualitative smell assessment. RESULTS. At the end of week 7 of radiotherapy, none of the patients was considered normosmic, 10 patients were considered to be suffering from hyposmia and 42 from anosmia. Statistically significant changes in the quantitative determination of odour occurred in the fourth week, respectively at the radiation dose of 40Gy. Qualitative odour assessment in this study showed a statistically significant decrease starting with the fifth week of radiotherapy, respectively with a radiation dose of 50Gy. CONCLUSION. Radiation therapy has a major impact on the quality of life of patients with laryngeal cancer, which has the lowest scores at the beginning and end of the treatment.

VOCs released from municipal solid waste at the initial decomposition stage: Emission characteristics and an odor impact assessment

The nuisance from odor caused by municipal solid waste (MSW) is resulting in a growing number of public complaints and concerns. Odor pollution occurs in the initial decomposition stage of MSW, including waste collection, transportation and early pre-treatment. Furthermore, decomposition takes place in waste facilities that are often close to living areas, which can result in odor impacts on local inhabitants. However, this aspect of odor impact from MSW has not been well studied. In the current study, lab-scale waste cells were designed to simulate MSW storage conditions in the early stage. The characteristics of VOCs emissions with different waste compositions were analyzed. The odor concentration (CO, non-dimensional) method and odor intensity were used for the assessment of odor. Ethanol was the substance with highest emission rate. The release rate of VOCs increased with the growth easily biodegradable waste (EBW). VOCs emissions was reduced by 25% when the proportion of EBW decreased from 60% to 45%. Methyl sulfide, ethanol, dimethyl disulfide and ethyl acetate were identified as typical odorants. The EBW proportion in waste is the main factor significantly influencing odor pollution. The CO was 244.51 for the 60% EBW condition, which was only 61.46 for 15% EBW condition. These study results provide important information for the implementation of a garbage sorting policy and the monitoring of odor pollution from waste management.

A Flexible and Printable Chemiresistor Sensor Array for Detection and Recognition of Aging-Associated Human Body Odor

Introduction Human skin emits a variety of volatile organic compounds that are perceived as unique body odor [1]. It has been believed human body odor contains a large amount of information related to body chemistry of individuals. During recent years, there has been great interest in aging-associated body odors since some compounds have been identified existing in specific age groups [2]. For example, diacetyl has been found is a key contributor for middle-aged male odor [3]. 2-nonenal has been detected only in people over the age of 40 (old person smell) [4]. Organic acids (such as hexanoic acid and its derivatives) are characteristic odor of young ages due to their active activity of eccrine sweat glands [2]. The detection and recognition of aging-associated body odor may suggest many potential applications. However, the assessment of body odor at present mainly depends on human panelist and lack of effective sensing approaches. In this work, a flexible and printable chemiresistor sensor is developed for the detection and recognition of aging-associated odor compounds. The fabrication process of the sensor, the selection method of sensitive materials, and the pattern recognition of an optimized sensor array on three typical odor substances (hexanoic acid, diacetyl and 2-nonenal) are introduced. Materials and Method The chemiresistor sensor was prepared by using conductive composites of carbon black (CB) with various sensing materials. Many materials have been reported that can be used in the fabrication of CB-based chemiresistor sensors including polymers, lipopolymers, low volatility organic molecules, intrinsic conducting polymers, gas chromatography stationary materials, and so on. How to select those materials that are suitable for the sensing of body odor is a problem. In this work we investigated and compared the performance of about fifty materials commercially available. The chemiresistor sensors were prepared by mixing CB and the sensitive materials in tetrahydrofuran (or chloroform) with appropriate critical concentrations. Interdigitated array (IDA) electrode was prepared by a commercial inkjet printer using Ag conductive ink and polyethylene terephthalate (PET) film. The CB suspensions of different sensing materials were dropcast automatically by a digital dispenser on the IDA electrode to fabricate the array sensors. The performance of the sensitive materials was evaluated by their response on five McReynolds test probes (benzene, 1-butanol, 2-pentanone, nitropropane and pyridine). The selectivity of sensor channels were analysis by principle component analysis (PCA) as well as multivariate analysis of covariance (MANCOVA). A 6-channel sensor array optimized according to F-values of Wilk’s Λ statistic was used for pattern recognition of hexanoic acid, diacetyl and 2-nonenal. Vapors with standard concentration (from several ppm to several tens of ppm) were generated by a calibration gas generation system (GASTEC, Japan). The response of chemresistor sensor was recorded by a home-made multiple channel sensing device and control software system. Results and Conclusions Figure 1 shows the illustrated experimental setup used for the generation and sensing of odor samples with standard concentrations. The flexible IDA electrode with 8 channels basically was prepared by a low cost inkjet printing process. The McReynolds probe compounds are generally used in gas chromatography to assess the separation capability of gas chromatography stationary phase. Here we use them as a reference to select the sensitive materials for the fabrication of sensor array. Figure 2a shows the response characteristics of twenty-four materials on the five McReynolds probes (The details of these materials was not disclosed in view of business consideration). Figure 2b shows the ordered F-value of the above 24 materials by analysis of MANCOVA. A large F-value means that the variable has high selectivity [5]. That is to say, the materials holds high discrimination ability in the array. The chemiresistor sensor array can be then optimized by comprehensive consideration both the selectivity (F-value) and sensitivity (response intensity over 5 ‰). For example, the red mark in figure 2b lists an optimized sensor array including 6 channels ( No.13, 34, 32, 20, 23 and 16). Figure 3 shows the PCA result of the optimized sensor array on the McReynolds probes. The five compounds are well separated in the PCA plot which demonstrates that the optimized sensor array may exhibit a broad range of ability to discriminate odorant molecules. This result provides us a guiding principle to design sensor arrays for different sensing targets. The sensor array is then used for sensing of hexanoic acid, diacetyl and 2-nonenal. The PCA plot shown in figure 4 demonstrates that it succeeds in the detection and recognition of aging-associated human body odors. Considering the excellent body odor sensing performance as well as printable and flexible characteristics, it is promising that the chemiresistor sensor array can be further developed as a wearable device and applied for body odor-related biomedical and health application.

Identification candidate for odour assessment and evaluate validity and reliability among wound care nurses

This study aims to identify a candidate for odour assessment and evaluate the validity and reliability among wound care nurses. The first stage used the Delphi method to obtain an agreement of candidate odour assessment. The second stage used cross-sectional to evaluate the reliability of selected odour assessment among wound care nurses. The Delphi study recommends the usage of odour assessment scoring tools in clinical practice. The concurrent validity of odour assessment scoring tool based on bacterial burden (p=0.042) with (r=0.43). Interrater Reliability Test by Cronbach alpha confirmed robust correlation (r=0.91), of the odour assessment scoring tools between rater A and rater B. The odour assessment scoring tools are valid and reliable to be applied.

Odour Assessment for a Pig Farm Through Dynamic Olfactometry and Air Dispersion Modelling in Order to Reduce the Odour Pollution Using Biotechnologies

Odour represents one the most actual topics in terms of industrial pig farming pollution effects, mainly because of the increasing number of settlements build in traditional farming areas but also because of the overpopulation of pigsties. The odour impact assessment was requested by a big pig farm in order to comply to the request of the Environmental Agency to reduce the odour impact on nearby settlements. Odour assessment was done using dynamic olfactometry, mathematical modelling of dispersion and FIDOL factors. The initial assessment was used to elaborate and apply an odour management plan based on biotechnologies which consisted mainly in biological treatments applied to the floor of the pigsties, the slurry transportation channels and the slurry tanks with specific products designed to reduce the Ammonia level, break down her sulphurous compounds in the slurry and increase the quality of the slurry as fertilizer, with the final target of reducing the odour emissions. Results indicate a considerable decrease of odour concentrations in the closest settlements, around the farm and inside pigsties. Further measures must be taken as the concentrations are still over the limit values from most European countries.

Sensory evaluation in test chambers: Influences of direct and indirect assessment

The release of volatile organic compounds from building products may influence the perceived air quality in the indoor environment. Consequently, building products need to be assessed for the acceptability of emitted odors. The standard ISO 16000-28 describes the evaluation of perceived odor in test chambers with trained panelists, being calibrated with diluted acetone. For the direct odor assessment, ISO 16000-28 requires an air flow of 0.6–1.0 l/s at the chamber outlet. To meet these conditions under normal air exchange rates, the minimum chamber volume is about 3 m³. If smaller chambers are used, air must be collected into containers for an indirect assessment. Procedures for the handling of the containers are provided in the ISO standard. Nevertheless, the indirect assessment method has a number of pitfalls and drawbacks. Experiments with sampling-container materials such as Nalophan™ and Tedlar® and different sampling techniques (continuous vs. discontinuous) have shown that the composition of sampled air might be influenced by the container material due to sink effects and leakage. The recoveries of the target VOCs in the sampling container decreased in dependence of decreasing vapor pressure and increasing octanol/air distribution coefficient.1-butanol and 1-hexanol have high recovery rates in Nalophan™ containers. These substances therefore appeared to be suitable for investigations into the synergistic odor effect. It could be shown that mixtures of 1-butanol and 1-hexanol have no clear additive effect in the sensory evaluation. This calls into question the practical relevance of an odor guide-value concept based on individual substance evaluations.

The odour assessment of thyme essential oils in electrospun fibre mat with a virtual sensor array data and its relation to antibacterial activity

Aims: The ability of a single-sensor gas diagnosis device (SSGDD) as a virtual sensor array data to appraise thyme essential oils (TEO) based on its quantitatively release rate from nanofibres was aimed.Methods: To form nylon 6 fragrant electrospun nanofibre, TEO was added as a natural antibacterial substance under homogeniser to make a stable emulsion.Results: The optimised nanofibre inactivated against Escherichia Coli and Staphylococcus Aureus bacteria up to >75% at once and to > 41.9% over 2-weeks period. Moreover, large differences in sensor responses to samples with experimental variables (percent TEO and storage time) and different odour intensity exist which correctly classified by discriminant function analysis.Conclusions: Odour intensity as an accessible incubator evinces the nanofibres efficiency which correlated to the antibacterial activity. With applying SSGDD technique as a quantified subjective solution, carefully odour assessment is possible and prepared mats could be demonstrated as a face-masks’ promising candidate.

A review on the use of air dispersion models for odour assessment

A review on the use of air dispersion models for odour assessment

Quantification of Acrylonitrile Butadiene Styrene Odor Intensity Based on a Novel Odor Assessment System With a Sensor Array

As an engineering plastic, acrylonitrile butadiene styrene (ABS) has been widely used in the automobile trims. The odor intensity of ABS can be considered as an important reference for the quality of in-vehicle air. Currently, many automobile manufacturers employ their own testing methods to measure the odor intensity of the trims. Different rules lead that the market lacks a unified standard to evaluate the odor intensity. In this paper, a novel odor evaluation system was proposed to measure the odor intensity of ABS. According to coefficient of variation (CV), analysis of variance (ANOVA), and principal component analysis (PCA), eight sensors were selected to compose an array with stability, repeatability, and selectivity. By means of the pretreatment and the feature extraction, the odor features were quantified by grey relation analysis (GRA). Then, the regression models were constructed by extreme learning machine (ELM), random forest (RF), and support vector machine (SVM) to predict the odor intensity. The results indicated that the quantified data could describe the odor intensity accurately and be predicted well by three models. This study demonstrated that the system achieved perception and quantification of the odor intensity of ABS. In conclusion, a self-developed system was put forward, offering a new technique to evaluate the odor intensity, prospective to replace the manual testing.

A review on the use of air dispersion models for odour assessment

Only recently have unpleasant odours become an important environmental issue and a specific legislation is being developed and implemented. The assessment of odour impact involves several different aspects (large number of odorants, human sensitivity, different perception thresholds, etc.) and it is dealt with by the application of different techniques and methods. In this paper a review about the reliability of air dispersion models applied to odour impact assessment determined by different type of sources is presented, based on the analysis of 69 case studies published over the last 10 years. The Gaussian models were the most used technique (67% of case studies) often accompanied with results validation with experimental data. The analysis of the case studies and related validation processes highlighted the reliability of dispersion models if some critical issues, such as the presence of particular climate conditions, duration of averaging times and position of important receptors, are known and correctly managed.

ODOUR POLLUTION ASSESSMENT THROUGH INDIRECT METHODS BASED ON THE MONITORING OF TECHNOLOGICAL PARAMETERS - CASE STUDY

The odours in the ambient air, through the discomfort that they induce, represent an actual problem for the communities located nearby companies with technological processes that emit in the air different strong and unpleasant odorous substances. The standard method for odour assessment involves measuring the concentration through dynamic olfactometry according with SR EN 13725:2003, a very complex method that requires specialized working staff and expensive equipment. The paper presents an indirect method for odour assessment in the ambient air, based on monitoring the process and meteorological data - Predictive Emission Monitoring Systems (PEMS) and it is applied to a livestock farm. Using the multiple regression analysis of the monitoring data for the most important specific technological and meteorological parameters it can be developed a mathematical model that could be used for the calculation of odour concentration in air, without the necessity of direct measurement, after the initial step. For the case study presented in the paper, the distance between the slurry lagoon was identified as a significant statistical parameter that can determine in a proportion of 72% the concentration of odour in the ambient air nearby the farm; the margin of error for odour concentration assessment, according to the model validation tests, is ± 8%, acceptable value for an estimation method by mathematical modelling.

The influence of the basil on colour, odour and taste of frankfurters

Plants from the moderate climate zone are rarely used as seasoning in pasteurised sausages. Seasoning plants of the family Lamiaceae belong to this group (marjoram, basil, savory, sage, thyme). One of the reasons these herbs are rarely used to season meat products is the presence of the plant pigment, chlorophyll that can have undesirable influence on colour, odour and taste of meat products. The aim of this paper was to assess the influence of basil on colour, odour and taste of vacuum-packed frankfurters during 28 days of storage. Powdered, dried basil (0.1%, 0.3% and 0.5%) was added to frankfurters while control frankfurters were produced without herbs or spices. Assessment of colour, odour and taste acceptability of the frankfurters was performed by a panel of five assessors using a quantitative descriptive test, and the results of the ranking test were analysed statistically. When used at the level of 0.1% in the sausages, basil did not have negative influence on frankfurter colour, while larger quantities 0.3% and 0.5% adversely affected frankfurter colour. Basil in the smaller amounts of 0.1% and 0.3% stimulated development of a pleasant odour and taste in the frankfurters, while 0.5% basil had an undesirable effect on these sensory attributes.

The Effectiveness of Gas Recovery Systems for Managing Odour from Conventional Effluent Treatment Ponds in Palm Oil Mills in Malaysia

Gas recovery systems at palm oil mills enable the curtailment of uncontrolled greenhouse gas emissions from open anaerobic pond, but can also reduce odour, an aspect which has not yet been substantiated. The objective of this study is to evaluate the odour emission from palm oil mill effluent and the effectiveness of covers and tank digester in reducing odour emission from the open lagoons. Odour samples were obtained from the cooling ponds in conjunction with in-field odour assessment performed on site. Results demonstrated that odour released from open ponding or covered lagoon were almost comparable, ranging from 33,150 – 162,000 OU/m<sup>3</sup>, and 68,705 – 102,000 OU/m<sup>3</sup>, respectively. In contrast, odour emission from cooling pond which used tank digester system seemed markedly lower, ranging between 13,000 – 76,000 OU/m<sup>3</sup>. In fact, the analysis of ambient air close to anaerobic tank digesters proved a reduction of odour emission to the surroundings (with 3.5 OU/m<sup>3</sup>, weak intensity) compared to open pond (with 2700 OU/m<sup>3</sup>, strong intensity) or covered lagoon (with 111 OU/m<sup>3</sup>, distinct intensity). In conclusion, gas recovery systems at palm oil mills should be promoted not only towards the management of greenhouse gaseous, but also as an odour impact management strategy.

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.

Measurement of Odour on Source of Drinking Water Using Threshold Odour Number and Modified Olfactometry

Concerns on odour of water have increased rapidly. However, odour measurement in water for drinking sources has yet to be established in Malaysia. More study is needed for an approach to quantify the odour incidences in water supply, one that is effective and applicable as a guideline towards the early identification of contamination occurrences. Thus, the objective of this study was to identify correlation (if any) between Threshold Odour Number (TON) test with a portable olfactometry plus odour wheel (POPOW) combination method for assessing odour in drinking water. Water samples collected from a drinking water supply system was tested for odour concentration as well as its character based on an odour wheel. Results from the Pearson correlation showed that the TON and POPOW gave the r-value of 0.833 which indicates that both method highly correlate with a level of confidence of 99 percent. Sample water that was taken near the main source of drinking water was given off as earthy smell, indicating geosmin as a likely contaminant. On the other hand, treated water samples taken directly at the treatment plant had a distinctive, chlorinous odour, which was expected from it use of chlorine as a disinfectant. This study has demonstrated the effectiveness of the portable olfactometer and odour wheel combination method for detecting odour in drinking water supply with at par results to the standard TON. More importantly, POPOW would enable the assessment of odour at site and at a shorter test preparation time, traits which are important especially for remotely located sites.

Do odour impact criteria of different jurisdictions ensure analogous separation distances for an equivalent level of protection?

Governments are increasingly introducing odour impact criteria (OIC) to determine separation distances between odour sources and residential areas. Previous studies have shown the wide range of OIC available for this purpose, depending on the desired level of protection against odour annoyance. However, it is unclear whether OIC with similar levels of protection can ensure analogous separation distances, which would reasonably be expected. This study presents a comparative analysis of separation distances calculated at two sites for different OIC, but all related to an equivalent level of protection. Here, the equivalent level of protection was defined for urban residential areas (land use), swine odour (hedonic tone) and new facilities (facility type). In this manner, the regulatory criteria currently enforced in Germany, Ireland, and Queensland (Australia) were selected as references for the investigation. The results clearly show that, even for an equivalent level of protection, disparate separation distances can be obtained. Differences in separation distances were found to be greater in prevailing wind directions compared to distances in additional wind directions. Overall, the results demonstrate a risk of poor conclusions in odour assessments. This means that care must be taken when adopting OIC for decision making, principally in those countries that have not yet established specific regulations to manage environmental odours. Concomitantly, the results stress the need for better harmonisation of the concept of the odour impact criterion and components thereof. By using perturbation analysis, it has also been found that the stack exit temperature influences the separation distances in a distinct way, reliant on the criteria used to determine the distances. This finding is of significance for input data collection in future odour modelling studies. Furthermore, approaches used to derive OIC, equivalence between dispersion modelling and field inspections (European standard EN 16841-1), as well as implications of the findings for regulatory practice are summarised and discussed.