Evaluation Of Indoor Air Quality Research Articles

Experimental and Modelling Investigations of Air Exchange and Infection Transfer due to Hinged-Door Motion in Office and Hospital Settings

Occupants spend a significant amount of time indoors where temperature and air quality has an important impact on their comfort, health and work performance. Understanding the role of airflow exchange between spaces is crucial to describe the processes of mixing and transport of substances driven by air motion and therefore essential for evaluating indoor air quality. This work presents the results of field measurements and laboratory experiments designed to characterise door operation and to quantify its influence on air volumes exchanged between rooms due to door motion. The field study was conducted to identify typical total door cycle times in single person offices. The laboratory experiments were conducted in a scale model to investigate the exchange flow between two generic rooms. The model consisted of a water filled tank divided into two equal rooms, which were connected by a computer-controlled hinged door. Flow visualisations were used to describe flow patterns and concentration measurements of Rhodamine WT were performed to quantify exchange volumes. With hold open times of between 0s and 26.67s the total fluid volume exchanged was found to be between 67% and 98% of the total volume swept. Based on the exchange volume found in these experiments combined with the Wells-Riley equation the effect of ventilation rate on the probability of occupants in an adjacent room becoming infected was investigated. With ventilation rates for a medium air quality the risk of infection is low (<0.05). However, the probability of infection quickly rises with lower ventilation rates.

Indoor air quality and thermal comfort evaluation in a Spanish modern low-energy office with thermally activated building systems

In the current context of a world energy situation that demands high-quality indoor environments compatible with rational energy use, the purpose of this work is to present a successful case study of a comfortable low-energy office building in Madrid, Spain. An exhaustive indoor air quality and thermal comfort field measurement survey was carried out during the summer period. The main global and local thermal comfort parameters in several workplaces, as well as CO2 concentration in supply air, exhaust air, and occupied space, were registered. Correct operation of the demand-controlled ventilation system and air distribution is observed. Also, thermally activated building systems and shading design make it possible to get high levels of indoor thermal comfort, as derived from measurements. This proves that the integration of novel energy-efficient concepts in office building design can not only contribute to a minimization of the energy use but can simultaneously favor the achievement of high indoor environmental quality.

A surface acoustic wave bio-electronic nose for detection of volatile odorant molecules.

In this work, a "bio-electronic nose" for vapour phase detection of odorant molecules based on surface acoustic wave (SAW) resonators is presented. The biosensor system is composed of an array of five SAW resonators coated with three types of odorant-binding proteins (OBPs): the wild-type OBP from bovine (wtbOBP), a double-mutant of the OBP from bovine (dmbOBP), and the wild-type OBP from pig (wtpOBP). High resolution deposition of OBPs onto the active area of SAW resonators was implemented through laser-induced forward transfer (LIFT). The resonant frequency shifts of the SAW resonators after the deposition of the biomolecules confirmed the immobilisation of the proteins onto the Al/Au inter-digital transducers (IDTs). In addition, a low increase of insertion losses with a limited degradation of Q-factors is reported. The "bio-electronic nose" fabricated by LIFT is tested in nitrogen upon exposure to separated concentrations of R-(-)-1-octen-3-ol (octenol) and R-(-)-carvone (carvone) vapours. The "bio-electronic nose" showed low detection limits for the tested compounds (i.e. 0.48 ppm for the detection of octenol, and 0.74 ppm for the detection of carvone). In addition, the bio-sensing system was able to discriminate the octenol molecules from the carvone molecules, making it pertinent for the assessment of food contamination by moulds, or for the evaluation of indoor air quality in buildings.

Measurement and prediction of the indoor airflow in a room ventilated with a commercial wind tower

This paper introduces a method for a full assessment of the internal air movement characteristics in a room ventilated with a commercial wind tower using scaled wind tunnel and computational fluid dynamics (CFD) analysis. An accurate geometrical representation of the experimental situation was recreated in the CFD simulation. The experimental investigation was carried out using a closed-loop low speed wind tunnel and the indoor air flow distribution was measured and compared with the CFD analysis. Good correlation between the numerical and experimental results was observed (10% average error). Flow visualisation was also conducted to further analyse the airflow structure within the room. The work assessed several ventilation parameters to describe the indoor airflow characteristics such as the mean age of air (MAA), air change rate, and air change effectiveness (ACE). The MAA was calculated using the steady-state method, by solving an additional partial differential equation describing the transport of the scalar “age of air”. The numerical analysis of the MAA allowed to detect less or insufficiently ventilated areas. The CFD code could be useful for the calculation of the MAA and ACE, allowing reduction in time and cost in the evaluation of indoor air quality in buildings ventilated with wind tower or similar device.

Modeling the Dispersion of a Tracer Gas in a Model Room: Comparison Between the Large Eddy Simulation Method and a Euler Approach

Abstract In this paper, indoor tracer-gas concentration and temperature profiles obtained by a large-eddy simulation (LES) and an inviscid model based on Euler equations are presented. The numerical results from these two approaches are compared with experimental results, available in the literature, for both mixing jet and displacement ventilation strategies. The numerical results reveal that the ventilation strategy changes the dispersion of the tracer gas in the model room to a significant degree. Comparison between LES, Euler, and experimental data shows that the LES model can simulate the tracer-gas concentration and temperature distribution relatively well. Comparison between LES models, Euler, and experimental data show that the LES models simulate the concentration of the tracer gas and the temperature distribution reasonably well. The results of this model coincide well with the experimental results. The same finding was observed by the Euler model. Performance of this approach for evaluation of indoor air quality has been verified for two ventilation strategies. Differences from 3 to 4.7 % were observed between the Euler model and experimental results. The efficiency of ventilation obtained from the Euler model is almost identical to the experimental values with a calculation time less than that obtained by the LES model. The Euler model has its limits only when it comes to high velocities (near air outlets). Generally, a room's air flows are low so in this case, the Euler model can predict the concentration of pollutants effectively.

Evaluation of Thermal Environment and Indoor Air Quality in University Libraries in Vienna

This contribution presents the results of an indoor environmental study of university libraries in Vienna. Indoor climatic parameters (air temperature, relative humidity, and CO2 levels) in the main spaces of four different library buildings (two historic buildings from the 19th century, two buildings from the late 20th century) were monitored over a period of ten months. Furthermore, to obtain a general impression of the quality of the visual environment in these buildings, illuminance levels at selected locations were measured. The measured data was analyzed and enriched with additional calculated indicators (e.g., PMV/PPD). To put the monitored data in the proper context, recorded outdoor climate data was also taken into consideration. The findings point to a certain overheating risk during the summer period as well as increased CO2 levels during the winter period.

Reducing the Indoor Odorous Charge in Waste Treatment Facilities

Characterising and determining the odorous charge of indoor air through Odour Units (OU) is an advantageous approach to evaluate indoor air quality and discomfort inside municipal solid waste facilities. The assessment of the OU can be done through the determination of Volatile Organic Compounds (VOC) concentrations and their odour thresholds. The aim of the study was to evaluate the differences in the odorous charge in the organic matter pit of a mechanical-biological waste treatment plant with a processing capacity of 287,500 tons year-1. The sampling was carried out during the months of September 2012 (original situation) and October 2012 (after emptying the organic matter pit drain pipe). 150 chemical compounds were determined qualitatively in the studied location, from which 102 were quantified due to their odorous characteristics as well as their potentiality of having negative health effects. The results obtained demonstrated that after a maintenance cleaning operation such as draining the organic matter pit pipe, the odorous charge inside the facility can be diminished in a great way, up to a 95%.

Indoor air quality audit and evaluation on thermal comfort in a school in Portugal

Given the Portuguese national programme for rehabilitation of school buildings and the new regulations for thermal comfort and air quality in Portugal, whose demands contribute to increase energy costs, it became relevant to study a case before any refurbishment intervention, in order to assess the potential of different methods of actions and to improve results. It was also intended with this study to evaluate the indoor thermal quality and the indoor air quality experienced by the school occupants. From a practical case, a school in Coimbra, the procedure passed through the measurement of some environmental physical parameters [dry bulb temperature and relative humidity and the concentrations of chemical indicators, such as carbon monoxide and carbon dioxide]. Contributing to the indoor environment characterization, it was developed a survey directed to the occupants, in parallel with the measurements taken inside a classroom during a period in the heating season and another period in the ‘pre-cooling’ season. An estimation of the predicted percentage of dissatisfied and predicted mean vote comfort indices was done based on the school measured data. The results were compared with those obtained from the questionnaire. In the end, an analysis was also done based on CO2 concentration values.

Evaluation of indoor air quality in a museum (Bait Al Zubair) and residential homes

This study was conducted with an aim to know the extent to which artefacts displayed in a museum could be affected due to raised levels of indoor air pollutants. The other objective of this work was to identify whether the quality of air in the residential homes is acceptable for the residents or not. In order to fulfil these objectives, the levels of air quality parameters were recorded at various locations of the museum and residential homes. The determined values of these parameters were compared with the permitted values defined in international standards/guidelines. Results showed that the levels of nitrogen dioxide, relative humidity and temperature in the museum were within the allowable limits while that of ozone, sulphur dioxide and total particulate matters were above the thresholds, which could cause damage to the exhibits in the museum. Furthermore, the results obtained from the residential homes indicated that the elevated levels of carbon dioxide, total volatile organic compounds and temperature in the indoor environment of these homes could cause unhealthy effects to the residents.

Correlation of symptoms of sick-building syndrome to chemical and odor concentration levels

[Background] Sick-building syndrome (SBS) is a range of symptoms such as eye irritation, sore throat and headaches that occur when entering a newly constructed or remodelled building.Volatile organic compounds (VOCs) are suspected to be one of the major causes of SBS. In addition, there are reports that when people complain of symptoms of SBS, most of them also claim to smell an odour. [Aims] The aims of this study were (1) to quantify the odour in indoor air, (2) to examine the correlation between the concentration levels of total VOCs (TVOC) and SBS symptoms, and (3) to examine the correlation between odour and SBS symptoms. [Methods] The concentration levels of chemicals in indoor air of the 13 study sites in Chiba University were measured and analyzed.The odour threshold ratio (OTR) was developed to quantify odour by using odour threshold and concentration values for each VOC in indoor air.Next, for the evaluation of indoor air quality by human sensory perception, 218 healthy volunteers stayed for 15 minutes at the 13 study sites and answered questionnaires which inquired about the odour and symptoms. Then correlations of SBS symptoms to TVOC andtotal odour threshold ratio (TOTR) values were examinedstatistically among sensitive and insensitive groups. [Results] There were 218 subjects,of which 134 were female and 84 were male. 35.8% of females and 34.5% of males were classified as being sensitive to chemicals. The percentage of participants who complained of symptoms was 36.7%. It was found that TVOC and TOTR values were significantly correlated with SBS symptoms, especially among the sensitive group when the concentration level of TVOCs was greater than about 400 ?g/m3 (95%CI 1.06-14.33) and the level of TOTR was greater than about 40 (95%CI 1.03-20.35). [Conclusion] This study revealed the baseline level of TVOC that may cause SBS symptoms to be about 400 ?g/m3and a TOTR value of about 40.It also suggests that TOTR could be used asa new indicator forevaluating the effects ofindoor air quality on human health.

NADH-Fluorometric Biochemical Gas Sensor (Bio-Sniffer) for Evaluation of Indoor Air Quality

A fiber-optic biochemical gas sensor (bio-sniffer) for assessment of indoor formaldehyde (FA) is fabricated and tested in monitoring of FA degradation by TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The biosniffer measures FA vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of enzymatic reaction of FA dehydrogenase (FALDH). Usually, an enzyme loses its specific activity in the gas phase. This makes biochemical gas monitoring difficult. We employ a microflow-cell with a FALDHimmobilized membrane to prevent the FALDH from deactivation at the optode. An ultraviolet light-emitting diode (UV-LED) with peak emission of 335 nm is employed as an excitation light source. Emission of the UV-LED is introduced to the optode through an optical fiber and fluorescence of NADH is picked up coaxially at the optode. To improve the sensitivity, a multi-LED light source is introduced instead of the previously reported system. A photomultiplier tube is utilized as a photodetector. Continuous FA monitoring with biochemical method is successfully conducted with high selectivity at subppb level. Owing to the improved excitation source, the detection limit is improved to 750 ppt. A real-sample test is also carried out using a photocatalytic titania. A standard gas is flowed into a cell, in which photocatalyst glasses are located, and the FA level is measured using the biosniffer. Therefore, degradation of FA by the catalytic reaction of titania is monitored as reduction of FA in real time. According to the results, it is expected to be useful in fast and convenient monitoring of indoor FA.

Evaluation of indoor air quality based on qualitative, quantitative and olfactory analysis

In studying indoor atmospheric pollution, the concentration of air pollutants is considered to be the primary factor in judging indoor pollution level, while sensory effects accessed by olfactory analysis has not been paid enough attention. In this paper, twenty living rooms in Beijing including newly decorated, 3 months and 6 months after decoration were sampled once a day for 10 d, and qualitative analysis, quantitative analysis and olfactory analysis of volatile organic compounds were carried out. The results showed the concentrations of the 6 main compounds surpassed the limitation values released by World Health Organization; the pollutants with highest chemical concentrations were not the most odor active odorants. Olfactory analysis which measured the odor characters such as odor detection threshold (ODT), odor active value (OAV) and odor quality was a helpful tool to identify possible chemicals which cause indoor smelling issues, and it was necessary to access indoor air quality in combination with their chemical concentrations to give a comprehensive judgment on indoor air quality.

Screening indoor air quality evaluation in the Lithuanian theatre, music and cinema museum

Abstract Air pollution is a risk for human health and for the preservation of materials in particular cultural heritage objects. This paper presents the main results obtained in the project carried out by the Lithuanian Theatre, Music and Cinema Museum (LTMCM) and NILU-Norwegian Institute for Air Research. The main goal of the project was to perform a screening study and characterization of the indoor air pollution in the LTMCM. The results are used to assess the indoor air quality with regard to the preservation of cultural heritage objects therein. Measurement of NO2, organic acids (i.e. acetic and formic acids), photo-oxidant effects of the environment, climate (temperature and relative humidity) and particulate matter deposition were performed in different indoor locations. Low concentration of outdoor generated pollutants such as NO2 was found in storage rooms whereas higher concentrations were determined in the in the exhibition area. The results indicate that the building envelope does not protect ...

Characterization and determination of the odorous charge in the indoor air of a waste treatment facility through the evaluation of volatile organic compounds (VOCs) using TD–GC/MS

Municipal solid waste treatment facilities are generally faced with odorous nuisance problems. Characterizing and determining the odorous charge of indoor air through odour units (OU) is an advantageous approach to evaluate indoor air quality and discomfort. The assessment of the OU can be done through the determination of volatile organic compounds (VOCs) concentrations and the knowledge of their odour thresholds. The evaluation of the presented methodology was done in a mechanical–biological waste treatment plant with a processing capacity of 245.000tonsyear−1 of municipal residues. The sampling was carried out in five indoor selected locations of the plant (Platform of Rotating Biostabilizers, Shipping warehouse, Composting tunnels, Digest centrifugals, and Humid pre-treatment) during the month of July 2011. VOC and volatile sulphur compounds (VSCs) were sampled using multi-sorbent bed (Carbotrap, Carbopack X, Carboxen 569) and Tenax TA tubes, respectively, with SKC AirCheck 2000 pumps. The analysis was performed by automatic thermal desorption (ATD) coupled with a capillary gas chromatography (GC)/mass spectrometry detector (MSD). One hundred and thirty chemical compounds were determined qualitatively in all the studied points (mainly alkanes, aromatic hydrocarbons, alcohols, aldehydes, esters, and terpenes), from which 86 were quantified due to their odorous characteristics as well as their potentiality of having negative health effects. The application of the present methodology in a municipal solid waste treatment facility has proven to be useful in order to determine which type of VOC contribute substantially to the indoor air odorous charge, and thus it can be a helpful method to prevent the generation of these compounds during the treatment process, as well as to find a solution in order to suppress them.

Evaluation of Indoor Air Quality in Classrooms Equipped with Cross-Flow Ventilation

In this work the evaluation of indoor air quality in a classroom equipped with cross-flow ventilation is presented. A numerical methodology, based on comparison with experimental data, used in the evaluation of the air exchange rate, airflow rate and the age of the air, was applied in the first phase of this work. The evolution of carbon dioxide inside spaces, with different airflow typologies, was then predicted in the second part. The study was based on a school located in the South of Portugal. In the experimental methodology the tracer gas decay method was applied. In order to reduce the experimental time, the first minutes of the test were measured, while the remaining decay was obtained using a numerical exponential regression. Natural and forced cross-flow ventilation topologies were analyzed. In the case of forced ventilation, fresh air from the external environment was driven into the classroom through an air inlet using a supply fan. An extract strategy was also used in which stale air was mechanically extracted from the classroom. Natural ventilation consisted of opening perimeter and above-door windows. The forecast of carbon dioxide evolution was made using software that evaluates the thermal response of and air quality in a building with complex topology. The numerical model used to evaluate internal air quality was based on energy and mass conservation integral equations. These were solved using the Runge-Kutta-Fehlberg method with error control.

Indoor Air Quality and Thermal Comfort Evaluation in Latvian Daycare Centers with Carbon Dioxide, Temperature and Humidity as Indicators

Latvian children under the age of 7 can spend up to 60 hours per week in daycare centers and therefore it is very important to establish a healthy and comfortable daycare environment that children will find pleasant and stimulating to stay in. This study investigates the indoor air quality and thermal comfort within six daycare centers (old, renovated and new-built) in moderate climate zone of Latvia. The measurements of carbon dioxide, air temperature and relative humidity were carried out, and the data regarding daycare center characteristics and maintenance activities were collected via combination of field visits, record analysis and interviews. It was found that the carbon dioxide concentrations exceeded 1000 ppm in 75% of the daycare centers studied, with the highest (1356 ppm) measured in a renovated facility with the natural ventilation system. Thus, installation of a more efficient ventilation system (mechanical) is recommended to provide acceptable indoor air quality, since opening of windows itself cannot provide the optimal conditions indoors. In all facilities the temperature was kept above 20°C and the average relative humidity was 40 ± 5%, creating comfortable thermal environment for children.

Comparative Study on Indoor Air Quality Evaluation Method

This paper reviewed six kinds of indoor air quality (IAQ) evaluation methods, by which the same IAQ status were evaluated. Besides, the relations and distinctions of six methods were also analyzed. The results indicate that the evaluation results of different methods on the same sample are not identical. Fuzzy comprehensive evaluation method, pollution loss rate method and comprehensive index method are relatively accurate, and improved grey relational analysis method has the largest error.

Single-Particle Analysis in An Indoor Working Environment in Valencia, Spain

Actually is recognized the importance of indoor air environment and associated health risks. In order to evaluate indoor air quality and to characterize the particles in terms of size, composition and shape were done measurements of the suspended particulate matter in a mechanical workshop of the Polytechnic University of Valencia (Spain). These measurements were performed using scanning electron microscope (SEM) with energy dispersive X-ray microanalysis (EDX) and image digital analysis. To differentiation of individual particles in the fine- ultrafine fraction, in some case, was used the atomic force microscopy (AFM). Multivariate statistics, such as hierarchical cluster analysis and factor analysis were appliqued and allowed to establish groups of elements and in this way to facilitate the identification of the natural and anthropogenic sources. It is confirmed that indoor air is influenced by outdoor surroundings and the anthropogenic sources due to the daily activity.

A finish material management system for indoor air quality of apartment buildings (FinIAQ)

With growing interest in the residential environment, the control of indoor air quality (IAQ) has become more important. When finish materials are selected considering pollutant source control in the design stage, the efficiency of IAQ control in the construction and use stages can be maximized. However, there have been little cases and researches of Database Management System (DBMS) establishment to choose interior finish materials with consideration of IAQ in the design stage. Thus, this study aims to carry out research on a system for selection of apartment house finish materials based on IAQ performance evaluation. For this, pollutants generated from interior finish materials and IAQ evaluation standards are looked into. Measures to apply to the selection system are presented considering comprehensive IAQ evaluation methods in the design stage. The outcome of this study can be utilized for building up a system to improve IAQ and material selection procedures.

Inspection and Analysis for IAQ of Public Buildings in Lingui

This paper conformed the indoor air quality evaluation of buildings in Lingui, using the designed evaluation system combined subjective assessment with objective evaluation. By calculating and analyzing the experiment data and survey data, the comfort and the main effecting factors of public buildings in Lingui was put forward herein. Eventually appropriate measures were proposed to improve the indoor air quality.