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.     

Comparison of three small chamber test methods for the measurement of VOC emission rates from paint

The aim of this study was to demonstrate a correlation between the measurement of emission rates of volatile organic compounds (VOCs) in three different climate chambers. In order to achieve this aim, the early state of the emission process in the three chambers was investigated and the effects of some important factors on the emission rates from paint were determined. The paper presents results of measurements in three different climate chambers. For the study, a 1-m3 chamber, a field and laboratory emission cell (FLEC), and a chamber for laboratory investigation of materials pollution and air quality (CLIMPAQ) were used. The airflow and surface area were selected so that the area-specific ventilation rates were identical in the three chambers. Temperature and relative humidity were identical during all the measurements. The paint examined was a solvent-based alkyd paint intended for indoor, which use contained between 30 and 60% of white spirit in wet condition. The paint was applied to electropolished and cleaned stainless steel plates. After application, the test material was stored for 14 days for drying in a well-ventilated conditioning room before the measurements were made. After 2 weeks storage, the most pronounced emissions were pentanal, hexanal, octanal, and decanol. The period before the emission rate stabilized differed for the three chambers studied. However, all chambers gave similar emission rates within the overall uncertainty used in these experiments.     

Formaldehyde and acetaldehyde exposure mitigation in US residences: in‐home measurements of ventilation control and source control

Measurements were taken in new US residences to assess the extent to which ventilation and source control can mitigate formaldehyde exposure. Increasing ventilation consistently lowered indoor formaldehyde concentrations. However, at a reference air exchange rate of 0.35 h^?1, increasing ventilation was up to 60% less effective than would be predicted if the emission rate were constant. This is consistent with formaldehyde emission rates decreasing as air concentrations increase, as observed in chamber studies. In contrast, measurements suggest acetaldehyde emission was independent of ventilation rate. To evaluate the effectiveness of source control, formaldehyde concentrations were measured in Leadership in Energy and Environmental Design (LEED)‐certified/Indoor airPLUS homes constructed with materials certified to have low emission rates of volatile organic compounds (VOC). At a reference air exchange rate of 0.35 h^?1, and adjusting for home age, temperature and relative humidity, formaldehyde concentrations in homes built with low‐VOC materials were 42% lower on average than in reference new homes with conventional building materials. Without adjustment, concentrations were 27% lower in the low‐VOC homes. The mean and standard deviation of formaldehyde concentration was 33 μg/m³ and 22 μg/m³ for low‐VOC homes and 45 μg/m³ and 30 μg/m³ for conventional.     

Emissions of volatile organic compounds from polymer-based consumer products: Comparison of three emission chamber sizes

The ISO 16000 standard series provide guidelines for emission measurements of volatile organic compounds (VOCs) from building materials. However, polymer-based consumer products such as toys may also release harmful substances into indoor air. In such cases, the existing standard procedures are unsuitable for official control laboratories due to high costs for large emission testing chambers. This paper aims at developing and comparing alternative and more competitive methods for the emission testing of consumer products. The influence of the emission chamber size was investigated as smaller chambers are more suited to the common size of consumer products and may help to reduce the costs of testing. Comparison of the performance of a 203 L emission test chamber with two smaller chambers with the capacity of 24 L and 44 mL, respectively, was carried out by using a polyurethane reference material spiked with 14 VOCs during the course of 28 days. The area-specific emission rates obtained in the small chambers were always similar to those of the 203 L reference chamber after a few hours. This implies that smaller chambers can provide at least useful numbers on the extent of polymer-based consumer product emissions into indoor air, thereby supporting meaningful exposure assessments.     

Testing of Household Products and Materials for Emission of Toluene Diisocyanate

Abstract Polyurethane products were subjected to chamber testing to determine their emission rates of 2,4- and 2,6-toluene diisocyanate (TDI). The polyurethane (PU) products included carpet padding, furniture cushions, sheet foam, varnishes, and sealants, as well as a commercially-applied water sealant product for concrete that contained up to 4 percent TDI by weight. The PU products were screened in a 9-L glass chamber, under elevated temperature and chamber loading conditions, using both a time-integrated sampling and analysis method specific for TDI and a continuous but non-specific real-time monitor for isocyanates. None of the products normally found in residences showed a positive response in the screening tests, indicating that TDI emissions and consequently toxic effects from such products are negligible. However, the commercially-applied water sealant gave a positive response in the screening test. Further testing of that product at realistic temperatures showed initial TDI emission rates of about 300,000 μg/m²/hr, with emissions lasting only one hour or less. At 21 and 27°C, about 1 percent and 5 percent, respectively, of the TDI content of the product was released to the air. The emitted TDI was predominantly the 2,6-isomer, although the TDI originally present in the product was predominantly the 2,4-isomer.     

Determination of Exposure-Response Relationships for Emissions from Building Products

Abstract Building products have been shown to affect the perceived indoor air quality in buildings. Consequently, there is a need for characterizing the emissions from building products in sensory terms to evaluate their impact on the perceived air quality. Determining the exposure-response relationship between concentration of the emission from a building product and human response is recommended. A practical method is proposed based on an air-dilution system connected to the exhaust of a ventilated small-scale test chamber. The method was used to determine the exposure-response relationships for eight building products. For each building product, samples were placed in a test chamber. A typical room was used as a reference to calculate a building-realistic area-specific ventilation rate in the test chamber. A sensory panel assessed the immediate acceptability of polluted air at four different concentrations 3, 10 and 29 days after samples of the building products were placed in the test chambers. The exposure-response relationships show that the impact of dilution of polluted air on the perceived air quality varies between building products. For some building products it may only be possible in practice to improve the perceived air quality marginally by increasing dilution. The results of the present study suggest that for such building products, source control is recommended as the remedy for poor indoor air quality, rather than an increase of the ventilation rate.     

Sensory pollution loads in six office buildings and a department store

Sensory pollution loads were measured in six non-smoking office buildings with mechanical ventilation without recirculation, and in a non-smoking department store with an air-conditioning system and recirculation. Untrained panels assessed the air quality on normal weekdays with occupants in the buildings, and in the case of office buildings, also on weekends without occupants present. On both occasions the ventilation system was in operation as on a normal working day. Outdoor airflow rate, air temperature, relative humidity and concentration of carbon dioxide were measured. The sensory pollution load from the building (without occupants) was found in offices to be 0.11 ± 0.09 olf/m² floor, which agrees well with the load recommended for low-polluting buildings in CEN CR 1752. This load is only half of the sensory pollution load found in previous investigations in offices and assembly halls where smoking was allowed. The load from building and merchandise in the department store was 0.15 olf/m² floor. A table is provided listing the mean sensory pollution load of the buildings measured in the present and in previous studies carried out in the period from 1988 to 2001 in different types of buildings in Europe. The table covers 120 buildings including offices and assembly halls (with and without previous smoking), schools, kindergartens and a department store.     

Volatile organic compounds from building products—Results from six round robin tests with emission test chambers conducted between 2008 and 2018

Emission testing of volatile organic compounds (VOC) from materials and products is commonly based on emission test chamber measurements. To ensure the comparability of results from different testing laboratories, their measurement performance must be verified. For this purpose, Bundesanstalt für Materialforschung und -prüfung (BAM) organizes an international proficiency test (round robin test, RRT) every two years using well-characterized test materials (one sealant, one furniture board, and four times a lacquer) with defined VOC emissions. The materials fulfilled the requirements of homogeneity, reproducibility, and stability. Altogether, 36 VOCs were included of which 33 gave test chamber air concentrations between 13 and 83 µg/m³. This is the typical concentration range to be expected and to be quantified when performing chamber tests. Three compounds had higher concentrations between 326 and 1105 µg/m³. In this paper, the relative standard deviations (RSD) of BAM round robin tests since 2008 are compared and the improvement of the comparability of the emission chamber testing is shown by the decrease of the mean RSD down to 28% in 2018. In contrast, the first large European interlaboratory comparison in 1999 showed a mean RSD of 51%.     

The Danish Twin Apartment Study – Part II: Mathematical modeling of the relative strength of sources of indoor air pollution

Abstract This study deals with the modeling of air pollution in apartments from laboratory measurements of source strengths, using formaldehyde and Total Volatile Organic Compounds (TVOCs) as model pollutants. The sources in two test apartments were grouped into two: building-related sources and occupant-related sources. The measured source strengths and ventilation rates were used for the prediction of concentrations expected in the apartments. These predictions were compared to measurements in the apartment over 12 months. The conclusions were that the model predictions based on emission rates measured in the laboratory can be used to predict the long-term concentration of the two model pollutants in the apartments. Considering the measured differences in ventilation between the apartments, an occupant emission rate of between 0.2 and 0.3 mg/h/kg body weight could be estimated. Based on previous suggested limits of acceptable exposures of humans to VOCs, an acceptable average emission rate of VOCs from building materials in general was estimated to be about 30 (μ/m²/h. The modeling showed that during the first 200 days, building materials dominated the emissions. After this, sources relating to the occupants dominated. On average about half of the VOC pollution originated from the building materials.     

Impact of asthma,exposure period,and filters on human responses during exposures to ozone and its initiated chemistry products

The impact of asthma, exposure period, and filter condition downstream of the mixing box of air‐conditioning system on building occupants' perceptual response, work performance, and salivary α‐amylase secretion during exposures to ozone and its initiated chemistry products is studied. The experiments were conducted in a field environmental chamber (FEC) (240 m³) simulating an office environment. Experiments were conducted during periods when the air‐handling system operated with new or used pleated panel filters at constant recirculation (7/h) and ventilation (1/h) rates. Average ozone and secondary organic aerosols (ozone‐initiated chemistry products) measured during non‐asthmatic and asthmatic subjects' 3‐h exposures in the FEC were in the ranges approximately 20–37 ppb and approximately 1.6–3 μg/m³, respectively. Asthmatic subjects' perceived odor intensity and sensory (eye, nose, and throat) irritation ratings were generally lower than those of non‐asthmatic subjects, possibly explaining why asthmatic subjects accept perceived air quality more than non‐asthmatic subjects. However, asthmatic subjects' perceived physiological‐like symptom ratings (flu, chest tightness, and headache) and concentrations of secreted salivary α‐amylase were generally higher than those of non‐asthmatic subjects. Asthmatic subjects had significantly lower accuracy than non‐asthmatic subjects in a task that required higher concentration although they had higher work speed. Filter condition did not make any significant difference for subjects' responses.     

Investigation of volatile organic compounds in office buildings in Bangkok,Thailand: Concentrations,sources, and occupant symptoms

To conserve energy, office buildings with air-conditioning systems in Thailand are operated with a tight thermal envelope. This leads to low fresh-air ventilation rates and is thought to be partly responsible for the sick building syndrome symptoms reported by occupants. The objectives of this study are to measure concentrations and to determine sources of 13 volatile organic compounds (VOCs) in office buildings with air-conditioning systems in the business area of Bangkok. Indoor and outdoor air samples from 17 buildings were collected on Tenax-TA^™ sorbent tubes and analyzed for individual VOCs by thermal desorption-gas chromatography/mass spectrometry (TD–GC/MS). Building ventilation was measured with a constant injection technique using hexafluorobenzene as a tracer gas. The results show that the VOC concentrations varied significantly among the studied buildings. The two most dominant VOCs were toluene and limonene with average concentrations of 110 and 60.5 μg m⁻³, respectively. A Wilcoxon sum rank test indicated that the indoor concentrations of aromatic compounds and limonene were statistically higher than outdoor concentrations at the 0.05 level, while the indoor concentrations of chlorinated compounds were not. Indoor emission factors of toluene and limonene were found to be highest with the average values of 80.9 and 18.9 μg m⁻² h⁻¹, respectively. Principal component analysis was applied to the emission factors of 13 VOCs, producing three components based on source similarities. Furthermore, a questionnaire survey investigation and field measurements of building air exchange pointed to indoor air complaints related to inadequate ventilation.     

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.     

Outdoor Air Contaminants and Indoor Air Quality under Transient Conditions

The indoor concentrations of contaminants originating from outdoor sources have been measured and calculated under transient conditions. The results show that contaminants that are supplied to an office building via the ventilation system can reach considerably high concentration levels. The indoor/outdoor concentration ratio and time lag are dependent on the air change rate. In buildings with low air change rates the indoor concentration variations are smoothed out compared to buildings with high air change rates. The results from the theoretical model are compared to the results from both laboratory and field measurements and the model is verified for well mixed conditions in a 20 m³ test chamber. The model can be used to simulate different control strategies for reduction of indoor contaminant concentrations related to outdoor sources. One such control strategy is based on reduction of the outdoor air change rate during periods with peak outdoor contaminant concentrations.     

Scaling model study of the air distribution in a powerhouse under different ventilation conditions

In order to clarify the air temperature distribution and air velocity distribution of a hydroelectric generating powerhouse in the mechanical ventilation mode, detailed ventilation experiments were conducted using a 1:20 small-scale model of a pumped-storage hydroelectric power station. In this model, we arranged fifty-seven circular inlets in double and triple rows to simulate the air supply pattern in a typical powerhouse. Six combinations of the inlets, and three air supply rates (28 m³/h, 56 m³/h, and 112 m³/h) were selected to determine the effect of the inlets’ arrangement and the air supply rates on the air distribution in the occupied zone of the powerhouse. A dimensionless method was adopted to process the acquired data of the air temperature and air velocity. The results revealed that the inlets’ arrangements and the air supply velocity had a significant influence on the air distribution in the powerhouse. Simultaneously, the ventilation efficiency of four heat sources was studied in the optimum case, i.e. the most effective air supply rate is 112 m³/h among the three tested values. The results of the experiments revealed that the air distribution was nearly independent of adjustable heat release rates. Our findings in this work may offer a significant advance in the understanding of ventilation system designs for hydroelectric powerhouses.     

Emission of Volatile Organic Compounds from Furniture Coatings

Abstract Emissions of volatile organic compounds (VOC) from different types of furniture coatings have been investigated by test chamber studies under dynamic conditions. A total of 150 VOCs could be identified in the chamber air. Compound groups occurring most often were aliphatic and aromatic aldehydes, ketones, aromatic hydrocarbons, glycols and esters. Special attention was paid to the detection of typical components of coating materials such as acrylic monomers, photoinitiators and other additives. The TVOC-values, measured after a preconditioning period of 20 days, ranged from 4 μg/m³ to 1288 μg/m³ with an arithmetic mean of 173.9 μg/m³ and a median 60.0 μg/m³. The highest chamber concentrations of individual components were found for some solvent residues such as n-butylacetate, butylgly-col, 1-butanol-3-methoxy-acetate and butyldiglycolacetate. The results have shown that furniture may contribute significantly to indoor air pollution. The calculated emission factors were comparable with data reported for other indoor materials.con     

Ventilation rates in schools

Research shows that poor indoor air quality (IAQ) in school buildings can cause a reduction in the students’ performance assessed by short-term computer-based tests; whereas good air quality in classrooms can enhance children's concentration and also teachers’ productivity. Investigation of air quality in classrooms helps us to characterise pollutant levels and implement corrective measures. Outdoor pollution, ventilation equipment, furnishings, and human activities affect IAQ. In school classrooms, the occupancy density is high (1.8–2.4 m²/person) compared to offices (10 m²/person). Ventilation systems expend energy and there is a trend to save energy by reducing ventilation rates. We need to establish the minimum acceptable level of fresh air required for the health of the occupants. This paper describes a project, which will aim to investigate the effect of IAQ and ventilation rates on pupils’ performance and health using psychological tests. The aim is to recommend suitable ventilation rates for classrooms and examine the suitability of the air quality guidelines for classrooms. The air quality, ventilation rates and pupils’ performance in classrooms will be evaluated in parallel measurements. In addition, Visual Analogue Scales will be used to assess subjective perception of the classroom environment and SBS symptoms. Pupil performance will be measured with Computerised Assessment Tests (CAT), and Pen and Paper Performance Tasks while physical parameters of the classroom environment will be recorded using an advanced data logging system. A total number of 20 primary schools in the Reading area are expected to participate in the present investigation, and the pupils participating in this study will be within the age group of 9–11 years. On completion of the project, based on the overall data recommendations for suitable ventilation rates for schools will be formulated.     

Plastics additives in the indoor environment--flame retardants and plasticizers

Phthalic acid esters and phosphororganic compounds (POC) are generally known as semivolatile organic compounds (SVOCs) and are frequently utilized as plasticizers and flame retardants in commercial products. In the indoor environment, both compound groups are released from a number of sources under normal living conditions and accumulate in air and dust. Therefore, inhalation of air and ingestion of house dust have to be considered as important pathways for the assessment of exposure in living habitats. Especially in the case of very young children, the oral and dermal uptake from house dust might be of relevance for risk assessment. A critical evaluation of indoor exposure to phthalates and POC requires the determination of the target compounds in indoor air and house dust as well as emission studies. The latter are usually carried out under controlled conditions in emission test chambers or cells. Furthermore, chamber testing enables the determination of condensable compounds by fogging sampling. In the case of automobiles, specific scenarios have been developed to study material emissions on a test stand or to evaluate the exposure of users while the vehicle is driving. In this review, results from several studies are summarized and compared for seven phthalic esters and eight POC. The available data for room air and dust differ widely depending on investigated compound and compartment. Room air studies mostly include only a limited number of measurements, which makes a statistical evaluation difficult. The situation is much better for house dust measurements. However, the composition of house dust is very inhomogeneous and the result is strongly dependent on the particle size distribution used for analysis. Results of emission studies are presented for building products, electronic equipment, and automobiles. Daily rates for inhalation and dust ingestion of phthalic esters and POC were calculated from 95-percentiles or maximum values. A comparison of the data with results from human biomonitoring studies reveals that only a small portion of intake takes place via the air and dust paths.     

Emission of phthalates from PVC and other materials

The main objective of this study was to generate quantitative and qualitative emission data on phthalates from different materials. To achieve this the existing (Chamber for Laboratory Investigations of Materials, Pollution and Air Quality) Climpaq-based procedure for simplified measurements of emissions of plasticizer from PVC and other plasticized materials was modified. It was applied to a range of products. Some of them were suspected of contributing to the indoor concentration of plasticizers. The emissions from PVC flooring, polyolefine flooring, a refrigerator list, two electric cables, PVC skirting and floor wax were studied in separate Climpaqs. The emission from the PVC flooring in the Climpaq was compared with results from the ultra-small chamber Field and Laboratory Emission Cell (FLEC). Sampling and analysis methods were optimized to measure plasticizers. Samples were taken in exhaust air from the chambers after 6, 35, 62, 105, and 150 days from the start of the experiment. PVC flooring was tested for an additional 100 days. Polyolefine covered with wax resulted in an air concentration of 22 microg/m3 of dibutylphthalate (DBP), which is two orders of magnitude larger than any other materials, but did not emit di(2-ethylhexyl)phthalate (DEHP). The other materials resulted in max concentration of approximately 1 microg/m3 of DEHP and low emissions of DBP. The concentration of DEHP in each chamber increased slowly to a rather stable level which was reached after 150 days. DBP concentrations in the chambers with PVC skirting, PVC flooring, polyolefine and floor wax reached their quasi-static equilibrium after 60 days. The modified method did not create sufficient data for the calculation of emission rates. Adsorption of emission on chamber surfaces made it impossible to use the first part of the experiment for emission rate calculation. When the concentration had stabilized, it was found to be almost identical and independent of chamber and ventilation rate. Emission rates were reduced at high concentrations probably because the concentration in the material was near equilibrium with the concentration in the chamber air.     

Radon and Natural Ventilation in Newer Danish Single-Family Houses

Abstract To investigate the effect of ventilation on indoor radon (²²²Rn), simultaneous measurements of radon concentrations and air change rates were made in 117 Danish naturally ventilated slab-on-grade houses built during the period 1984–1989. Radon measurements (based on CR-39 alpha-track detectors) and air change rate measurements (based on the perfluorocarbon tracer technique; PFT) were in the ranges 12–620 Bq m^?3 and 0.16?0.96 h^?1, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated uncertainty is discussed. It was found that differences in radon concentrations from one house to another are primarily caused by differences in radon entry rates whereas differences in air change rates are much less important (accounting for only 80,0% of the house-to-house variation). In spite of the large house-to-house variability of radon entry rates it was demonstrated, however, that natural ventilation does have a significant effect on the indoor radon concentration. Most importantly, it was found that the group of houses with an air change rate above the required level of 0.5 h^?1 on average had an indoor radon concentration that was only 50% (0.5±0.1) of that of the group of houses with air change rates below 0.5 h^?1. The reducing effect of increased natural ventilation on the indoor radon concentration was found to be due mainly to dilution of indoor air. No effect could be seen regarding reduced radon entry rates.     

Exposure and Emission Evaluations of Methyl Ethyl Ketoxime (MEKO) in Alkyd Paints

Abstract Small environmental chamber tests were conducted to characterize the emissions of a toxic chemical compound – methyl ethyl ketoxime (MEKO) – from three different alkyd paints. It was found that MEKO emissions occurred almost immediately after each alkyd paint was applied to a pine board. Due to the fast emission pattern, more than 90% of the MEKO emitted was released within 10 hours after painting. The peak concentrations of MEKO in chamber air correlated well with the MEKO content in the paint. Material balance showed that good recovery (more than 68%) was achieved between the MEKO applied with the paint and the MEKO emitted. The chamber data were simulated by a first order decay emission model assuming the MEKO emissions were mostly gas-phase mass transfer controlled. The model was used to predict indoor MEKO concentrations during and after painting in a test house. It was found that the predicted test house MEKO concentrations during and after the painting exceeded a suggested indoor exposure limit of 0.1 mg/m³ for all three paints. The predicted MEKO concentrations exceeded even the lower limit of a suggested sensory irritation range of 4 to 18 mg/m3 with two of the three paints tested. The model was also used to evaluate and demonstrate the effectiveness of risk reduction options including selection of lower MEKO paints and higher ventilation during painting.