Sensory Characterization of Emissions from Materials

Abstract The exposure-response relationship between the concentration of air pollutants and perceived air quality was studied for eight materials often found indoors and for a mixture of three of the materials. Samples of the materials were placed in a ventilated test chamber. The exhaust air from the test chamber was diluted with different rates of unpolluted air to obtain five different concentrations of polluted air. A sensory panel assessed the perceived quality of the five concentrations of polluted air. The exposure-response relationship differed between the materials and also from the corresponding relationship for human bioeffluents. The exposure-response relationships can be described by straight lines in a log-probit plot and be defined by two constants characteristic for each material. Determination of the two constants characterizing each material requires sensory assessments at least at two pollution concentrations. The sensory pollution load for a material may change with the pollution concentration in the air. The use of a simple measurement method based on a dilution system connected to a ventilated small-scale test chamber is proposed to characterize the emissions from materials in sensory and chemical terms.     

Impact of Temperature and Humidity on Chemical and Sensory Emissions from Building Materials

Abstract The chemical and sensory emissions from five building materials (carpet, polyvinyl chloride (PVC) flooring, sealant, floor varnish and wall paint) were tested under different combinations of temperature and relative humidity in the ranges 18–28°C and 30–70% relative humidity (RH). The experiment was performed in a climate chamber where a specially designed test system was built to study emissions from the five materials. The test system could provide different temperatures and humidities of air around the materials, while the air, after being polluted by the emissions from the materials, could be reconditioned to 23°C and 50% RH for sensory assessments. The experiment was designed to separate the direct impact of temperature and humidity on perception from the impact on sensory emission. The study found little influence of temperature on the emissions from the five materials whether expressed in chemical or sensory terms. The effect of humidity was found to be significant only for the waterborne materials – floor varnish and wall paint. Compared with the direct impact of temperature and humidity on the perception of air quality, the impact of temperature and humidity on sensory emissions from the building materials has a secondary influence on perceived air quality.     

Impact of varying area of polluting surface materials on perceived air quality

A laboratory study was performed to investigate the impact of the concentration of pollutants in the air on emissions from building materials. Building materials were placed in ventilated test chambers. The experimental set-up allowed the concentration of pollution in the exhaust air to be changed either by diluting exhaust air with clean air (changing the dilution factor) or by varying the area of the material inside the chamber when keeping the ventilation rate constant (changing the area factor). Four different building materials and three combinations of two or three building materials were studied in ventilated small-scale test chambers. Each individual material and three of their combinations were examined at four different dilution factors and four different area factors. An untrained panel of 23 subjects assessed the air quality from the chambers. The results show that a certain increase in dilution improves the perceived air quality more than a similar decrease in area. The reason for this may be that the emission rate of odorous pollutants increases when the concentration in the chamber decreases. The results demonstrate that, in some cases the effect of increased ventilation on the air quality may be less than expected from a simple dilution model.     

Sensory and chemical evaluation of odorous emissions from building products with and without linseed oil

Natural materials of biological origin degrade over time and may emit odorous chemical compounds that can influence the perceived indoor air quality. The objective of this study was to investigate how the perceived air quality is influenced by emissions from building products with linseed oil compared with similar conventional synthetic products without linseed oil. Two types of linoleum, two types of wall paint and two types of floor oil were selected as examples of natural products containing linseed oil. The selected synthetic products were PVC floor covering, a water-based paint, and a synthetic floor oil. The emissions from the products were monitored over a one-year period in small ventilated test chambers. The odorous emissions were evaluated by sensory panel assessments of odour intensity and acceptability and by chemical analysis of the odour-active volatile organic compounds (VOCs) and carbonyl compounds. Odour-active VOCs in the emissions from one floor oil with linseed oil and two pure linseed oils were detected by gas chromatography combined with olfactometry (GC-O) and attempted identified with mass spectrometry (MS). The products with linseed oil influenced the perceived air quality more negatively than the similar synthetic products and the odour was persistent over time. It was found that the products with linseed oil did not qualify for the Danish Indoor Climate Label, because of the persistency of the odour. The results of the GC-O/MS investigations and VOC measurements indicated that an almost constant emission of odour-active VOCs with low odour thresholds resulted in the persistency of the odour. The VOCs probably originated from oxidation products from the linseed oil used as raw material. The study indicates that the acceptability of the emissions from the floor oil was influenced by the linseed oil used as raw material. It is therefore suggested that systematic use of less odorous linseed oils may improve the acceptability of the emission from products with linseed oils. The applied combination of sensory assessment of perceived air quality and GC-O/MS seems to be a useful approach in the effort to eliminate unwanted odours from building products.     

The Influence of Area-Specific Ventilation Rate on the Emissions from Construction Products

Abstract Experiments were performed using small-scale climate chambers, including the new Chamber for Laboratory Investigations of Materials Pollution and Air Quality (CLIMPAQ), to gain knowledge about the influence of ventilation rate per plane specimen area (specific ventilation rate) on emission rates. Emissions from pieces of linoleum, waterborne acrylic paint, nylon carpet, and sealant were quantified at different specific ventilation rates. A trained sensory panel used the decipol scale and chemical analysis quantified some major Volatile Organic Compounds (VOCs) after the specimens had been conditioned in the chambers for six days. The results showed that the specific ventilation rate (L/s m2) may influence the emission rates. In both sensory and chemical terms, emission rates increased when ventilation was increased. At low specific ventilation rates the emission rate was proportional to the specific ventilation rate. For higher ventilation rates the emission rates stabilized and became independent of ventilation. The chemical measurements showed that only the emissions from the tested paint were influenced by ventilation rates above those comparable to 0.5 h^?1 in a typical room. The emissions quantified by the sensory panel continued, however, to be influenced by ventilation even at rates higher than 5 h^-1.     

Sensory evaluation of emissions from selected building products exposed to ozone

The interaction of ozone with eight different building products was studied in test chambers. The products were plasterboard, two types of paints on plasterboard, two types of carpet, linoleum, pinewood, and melamine-covered particleboard. Four months of conditioning prior to the experiment had left the products with a low emission. The products' ability to remove ozone from the air covered a wide range. For three of the products (plasterboard with paint, carpet, and pinewood), it was shown that the removal was primarily due to interactions in the products' surfaces and only to a minor extent due to gas-phase reactions. Sensory evaluations were carried out for five of the products, with different ozone-removal potentials. A sensory panel assessed the emissions from sets of two specimens of each product; one specimen was exposed to a high, but realistic, ozone concentration (10 or 80 ppb) and one specimen was exposed to no ozone (background level < 3 ppb). The panel assessed odor intensity and was asked to choose which odor of the two specimens they preferred. The perceivable changes in emissions due to exposure of the products to ozone depended on the type of product. The greatest effect was seen for carpet. Carpet was the only product that showed significantly higher odor intensity when exposed to ozone. Besides, the effect of ozone on preference was strongest for carpet and resulted in a clear negative sensory evaluation. A similar but less pronounced effect was seen for pinewood and plasterboard with paint. No clear preference was seen for melamine and linoleum.     

Sensory Pollution and Microbial Contamination of Ventilation Filters

Abstract The sensory pollution load and microbial contamination of glass-fibre filters at high and low relative humidity were investigated in an experimental set-up in the laboratory. Dust and particles from the outdoor air were collected in two EU7 glass-fibre filters for a pre-conditioning period of 16–18 weeks during which there was a constant airflow with a velocity of 1.9 m/s through the filters. One of the filters was exposed to outdoor air of approximately 40% relative humidity and 10°C, the other to outdoor air of approximately 80% relative humidity and 5°C. The dust in ventilation filters can constitute a serious pollution source in the indoor environment, causing deterioration in the quality of the supply air even before it enters the ventilated spaces. The sensory pollution load from the used filters after the continuous operating time of 16–18 weeks was significantly higher than the sensory pollution load from new filters but the sensory load at 40% and 80% relative humidity did not differ. The microbial contamination of the supply air downstream of the filters, which on average had been exposed to outdoor air of 40% and 80% relative humidity, was negligible.     

Assessment of the Health and Comfort Effects of Chemical Emissions from Building Materials: the State of the Art in the European Union*

Abstract The promotion of healthier indoor air requires the use of building materials whose chemical emissions are free of toxicity and unfavourable sensory properties. Testing and assessment of chemical emissions are essential in order to identify “safe” materials, and to encourage manufacturers to produce, and the market to adopt, such materials. Various testing and assessment procedures for building materials have been developed in European countries such as Germany, Denmark, Sweden, and Finland. Recently the European Collaborative Action “Indoor Air Quality and its Impact on Man” proposed criteria and a testing procedure for the assessment of VOC emissions from solid flooring materials. The innovative aspects of this proposal are: a procedure for the performance of chemical emissions testing; sensory testing coupled with toxicological evaluation; and a procedure to handle compounds for which toxicological information is scarce or absent. This procedure, after validation and experience from practical use, will probably be extended to other building materials.     

Evaluation of ozone emissions and exposures from consumer products and home appliances

Ground‐level ozone can cause serious adverse health effects and environmental impacts. This study measured ozone emissions and impacts on indoor ozone levels and associated exposures from 17 consumer products and home appliances that could emit ozone either intentionally or as a by‐product of their functions. Nine products were found to emit measurable ozone, one up to 6230 ppb at a distance of 5 cm (2 inches). One use of these products increased room ozone concentrations by levels up to 106 ppb (mean, from an ozone laundry system) and personal exposure concentrations of the user by 12–424 ppb (mean). Multiple cycles of use of one fruit and vegetable washer increased personal exposure concentrations by an average of 2550 ppb, over 28 times higher than the level of the 1‐h California Ambient Air Quality Standard for ozone (0.09 ppm). Ozone emission rates ranged from 1.6 mg/h for a refrigerator air purifier to 15.4 mg/h for a fruit and vegetable washer. The use of some products was estimated to contribute up to 87% of total daily exposures to ozone. The results show that the use of some products may result in potential health impacts.     

Building calibration for IAQ management

Demand Control System (DCV) is designed to optimise the energy consumption with respect to the demand of outdoor air quantity based on the number of people indoors. However, if significant indoor pollutant sources exist, which is not a function of the number of people, the DCV may cause the indoor air quality to be unacceptable. This paper discusses a procedure of calibrating the building in respect of managing the indoor air quality. The objective is to set the minimum fresh air quantity which is a function of the indoor pollutant concentrations rather than metabolic carbon dioxide. Radon is used as an example because it is a common pollutant embedded in the building materials of high-rise buildings in Hong Kong. This paper also presents a year-round record of the indoor air quality in a typical high-rise building which is very useful for building indoor air quality (IAQ) design.     

Location identification for indoor instantaneous point contaminant source by probability-based inverse Computational Fluid Dynamics modeling

Indoor pollutions jeopardize human health and welfare and may even cause serious morbidity and mortality under extreme conditions. To effectively control and improve indoor environment quality requires immediate interpretation of pollutant sensor readings and accurate identification of indoor pollution history and source characteristics (e.g. source location and release time). This procedure is complicated by non-uniform and dynamic contaminant indoor dispersion behaviors as well as diverse sensor network distributions. This paper introduces a probability concept based inverse modeling method that is able to identify the source location for an instantaneous point source placed in an enclosed environment with known source release time. The study presents the mathematical models that address three different sensing scenarios: sensors without concentration readings, sensors with spatial concentration readings, and sensors with temporal concentration readings. The paper demonstrates the inverse modeling method and algorithm with two case studies: air pollution in an office space and in an aircraft cabin. The predictions were successfully verified against the forward simulation settings, indicating good capability of the method in finding indoor pollutant sources. The research lays a solid ground for further study of the method for more complicated indoor contamination problems. PRACTICAL IMPLICATIONS: The method developed can help track indoor contaminant source location with limited sensor outputs. This will ensure an effective and prompt execution of building control strategies and thus achieve a healthy and safe indoor environment. The method can also assist the design of optimal sensor networks.     

Cleaning for Improved Indoor Air Quality: an Initial Assessment of Effectiveness

Abstract A study was conducted to characterize the indoor environment of a multifloor, multiuse, nonproblem, noncompliant building through long-term monitoring for biological, chemical, and particulate pollutants. The study also assessed the effects of cleaning on indoor air quality by providing a program to monitor baseline levels, providing a rigorous (deep) cleaning of the building, and then continuing to monitor after implementation of a standardized, improved, cleaning program. To assess the effectiveness of the cleaning program, air, surface, and dust data from monitoring prior to the cleaning program were compared with those obtained while the improved housekeeping program was in place. Correlations between pollutants and other environmental factors were studied. The data suggest that the improved cleaning program contributed to indoor air quality through the reduction of airborne dust mass, total volatile organic compounds, and culturable bacteria and fungi.     

Case Study of Factors contributing to a Crisis Building

Abstract Employees of a communications firm experienced an acute outbreak of nonspecific illness related to the workplace. Symptoms consisted primarily of coughing, throat irritation, shortness of breath and disorientation. Fifty-one individuals sought emergency medical care, and the building was evacuated. A multidisciplinary team was assembled to investigate and resolve the problem. Investigation activities focused on three major areas: epidemiology; environmental measurement; and mechanical engineering. Results indicated that the outbreak was due to multiple factors working in concert. The inside of the air handling system was contaminated with microbial growth and particulate matter; chemical products were used throughout the building with little control over use patterns; and the HVAC system was not delivering acceptable quantities of outdoor air to the employees’ breathing zones. Two unusual events may have triggered the employees’ response. An unusual odor/taste was reported, and the outside air damper abruptly opened and closed, possibly dislodging particulate matter from inside the air handling system. It appeared that psychosocial factors played an important role. Prevention of similar crises could be achieved by implementation of a policy/procedure that addresses specific responsibilities, communications, preventive maintenance, acceptable outdoor air ventilation rates, and guidelines for reporting and investigation.     

Perceived Air Quality,Sick Building Syndrome (SBS) Symptoms and Productivity in an Office with Two Different Pollution Loads

Abstract Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P= 0.04) and significantly lower levels of reported effort (P=0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P=0.003), typing 6.5% less text than when the pollution source was absent from the office. Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.     

VOC Emissions from Cork Products for Indoor Use

Abstract Complaints about unpleasant odour from wall, ceiling and floor coverings made of composite cork, induced chamber tests to study the emissions of volatile organic compounds (VOC) from composite cork products for indoor use. Emissions of phenol and furfural were found to be high, particularly those from cork parquet. Emission factors after 1 week ranged from 150 to 650 μg m^?2 h^?1 and from 15 to 350 μg m^?2 h^?1 for phenol and furfural, respectively, and decreased only slowly over time, by a factor of approx. 10 for a 6-month period. The ranges of emission factors were found to be similar for some solvents such as cyclohexanone or toluene which are constituents of varnishes used to protect cork surfaces. The emission of furfural may result from chemical reactions in the cork during the production process or may be caused by additives such as binders.     

Small Chamber Tests and Headspace Analysis of Volatile Organic Compounds Emitted from Household Products

A chamber method for the characterization of the complex composition and time dependence of volatile organic compound (VOC) emissions from household products is described and the results obtained for five household products (two liquid floor detergents, one wax, a spray detergent for carpets, and a spray polish for furniture) are reported and compared to headspace measurements. An empirical mathematical model has been used to describe the time dependence of VOC concentrations in the chamber. The model allows characterization of complex emissions and their time dependence with relatively few parameters. Significant differences in the composition of emissions determined in the chamber and in headspace air have been observed and are discussed in terms of polarity and water solubility of the emitted compounds.     

Sensory pollution from bag filters, carbon filters and combinations

Used ventilation filters are a major source of sensory pollutants in air handling systems. The objective of the present study was to evaluate the net effect that different combinations of filters had on perceived air quality after 5 months of continuous filtration of outdoor suburban air. A panel of 32 subjects assessed different sets of used filters and identical sets consisting of new filters. Additionally, filter weights and pressure drops were measured at the beginning and end of the operation period. The filter sets included single EU5 and EU7 fiberglass filters, an EU7 filter protected by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC. Furthermore, its pressure drop changed very little during the 5 months of service, and it had the added benefit of removing a large fraction of ozone from the airstream. If similar results are obtained over a wider variety of soiling conditions, such filters may be a viable solution to a long recognized problem. PRACTICAL IMPLICATIONS: The present study was designed to address the emission of sensory offending pollutants from loaded ventilation filters. The goal was to find a low-polluting solution from commercially available products. The results indicate that the use of activated carbon (AC) filters downstream of fiberglass bag filters can reduce the degradation of air quality that occurs with increasing particle loading. A more practical solution, yet comparably effective, is a stand-alone particle filter that incorporates AC. In either case, further testing under a variety of conditions is recommended before making design decisions regarding the type of filters best suited to efficient building operation.     

Modelling of Emission and Re-emission of Volatile Organic Compounds from Building Materials with Indoor Air Applications

Polymer materials and their additives are today ever present in our daily surroundings. These materials have been found to emit a number of different volatile organic compounds (VOCs) into the ambient air, thus affecting the quality of the indoor air VOCs with detectable concentrations are exchanged between the different materials and indoor air. Materials present in the system act as sorbents as well as sources of emission, depending on the concentration of the VOCs in the air at a specific time. This work demonstrates a method of studying the phenomena of absorption/re-emission. A hypothetical room that resembles a furnished office has been studied. A PVC flooring material was used as a primary emission source in a system where materials such as wood, paint, cloth, chipboard, and cellulose were present. Mass transfer in the solid materials was assumed to be by diffusion. The results show that the mechanism of absorption/re-emission of volatiles may extend the time of residence in an indoor system considerably. A person working in this environment could risk longer exposure to toxic volatiles than if there were no absorption/re-emission effects.     

Design and Characterization of the CLIMPAQ,Chamber for Laboratory Investigations of Materials,Pollution and Air Quality*

A test chamber has been developed in order to provide a small and simple emission testing facility capable of testing construction products in a climate where the important climatic parameters such as temperature, ventilation rate and air velocity can be varied independently around typical indoor values. The test chamber CLIMPAQ is made of panes of window glass. Other main surface materials are stainless steel and eloxated aluminium. The chamber has a volume of 50.9 litres and is designed to meet the requirements for quantifying air pollution. In this investigation human subjects acted as air pollution judges, and chemical characterization of the air pollution was carried out. Carpet, linoleum, wall paint and seal- ant were tested simultaneously in the CLIMPAQ and in four other chambers ranging from a full-scale chamber of 28 m³ to a field and laboratory emission cell of 3.5· 10^?5m³. Product ranking is the same in all chambers for the sensory measurements. Emission rates based on sensory measurements differ for all products less than 100 % except for tests in a 3-litre chamber where emission rates were higher. Chemical measurements differ up to approximately 10 times for the same product in different chambers. Deviations appear to be the result of different environmental parameters in the various chambers. Low air concentrations or high specific ventilation rates seem to increase emissions, while differences in air velocities and sink properties may also be the cause of differences in emission rates.