Showing papers in "Indoor Air in 1997"

Estimates of Improved Productivity and Health from Better Indoor Environments

Abstract: The existing literature contains strong evidence that characteristics of buildings and indoor environments significantly influence rates of respiratory disease, allergy and asthma symptoms, sick building symptoms, and worker performance. Theoretical considerations, and limited empirical data, suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases health and productivity. At present, we can develop only crude estimates of the magnitude of productivity gains that may be obtained by providing better indoor environments; however, the projected gains are very large. For the U.S., we estimate potential annual savings and productivity gains of $6 billion to $19 billion from reduced respiratory disease; $1 billion to $4 billion from reduced allergies and asthma, $10 billion to $20 billion from reduced sick building syndrome symptoms, and $12 billion to $125 billion from direct improvements in worker performance that are unrelated to health. Sample calculations indicate that the potential financial benefits of improving indoor environments exceed costs by a factor of 18 to 47. The policy implications of the findings are discussed and include a recommendation for additional research.

Total Volatile Organic Compounds (TVOC) in Indoor Air Quality Investigations

Abstract: The amount of volatile organic compounds (VOCs) in indoor air, usually called TVOC (total volatile organic compounds), has been measured using different definitions and techniques which yield different results. This report recommends a definition of TVOC referring to a specified range of VOCs and it proposes a method for the measurement of this TVOC entity. Within the specified range, the measured concentrations of identified VOCs (including 64 target compounds) are summed up, concentrations of non-identified compounds in toluene equivalents are added and, together with the identified VOCs, they give the TVOC value. The report reviews the TVOC concept with respect to its usefulness for exposure assessment and control and for the prediction of health or comfort effects. Although the report concludes that at present it is not possible to use TVOC as an effect predictor, it affirms the usefulness of TVOC for characterizing indoor pollution and for improving source control as required from the points of view of health, comfort, energy efficiency and sustainability.

TVOC and Health in Non-industrial Indoor Environments

Abstract: TVOC and health in non-industrial indoor environments. Report from a Nordic scientific consensus meeting at Langholmen in Stockholm

Are We Measuring the Relevant Indoor Pollutants

Abstract: Concentrations of volatile organic compounds (VOCs) measured indoors may exceed their odor thresholds, but are usually far below TLV estimates. Even applying additivity to eye and airway irritation effects, it is difficult to rationalize increased sick building syndrome (SBS) symptoms by exposure to generally chemically inert VOCs in the indoor environment. Several studies suggest that chemical reactions in indoor air are linked with SBS symptoms and the examination of these reactions may be necessary in order to understand the role of VOCs as causative agents of SBS symptoms. The usual evaluation of odor annoyance of VOCs based on odor thresholds should be modified, taking into account the large vari- ation of individual human odor thresholds for single substances, and specific additivity phenomena even at subthreshold levels of VOCs. The conclusion of this review is that chemical reactions between oxidizable VOCs and oxidants, such as ozone and possibly nitro- gen oxides, can form irritants which may be responsible for the reported symptoms. Compounds adsorbed to particles may also contribute to SBS symptoms. The individual effects of indoor pol- lutants may act in concert with temperature and relative hu- midity. New analytical methods are required to measure the oxi- dative and reactive species or specific markers thereof in indoor air.

Subjective Indoor Air Quality in Schools in Relation to Exposure

Abstract: This paper presents data on indoor air quality in schools as perceived by those working in them and relates these data to exposure measurements. Data on subjective air quality, domestic exposures and health aspects were gathered by means of a questionnaire which was sent to all personnel in 38 schools; it was completed by 1410 persons (85’4 of the total). Data on exposure were gathered by exposure measurements in classrooms. The results indicate that 53% of the personnel perceived the indoor air quality as bad or very bad. It was perceived as worse by those who were younger, those who were dissatisfied with their psychosocial work climate and those who were not exposed to tobacco smoke at home. In older school buildings and buildings with displacement ventilation there was less dissatisfaction with the air quality. There were no significant relations between complaints and air exchange rate or concentration of carbon dioxide. The air quality was perceived as worse at higher levels of exposure to a number of airborne compounds including volatile organic compounds, moulds, bacteria and respirable dust. It was concluded that exposure to indoor pollutants affects perception even at the low concentrations normally found indoors in nonindustrial buildings.

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

The Influence of Temperature on the Emission of Volatile Organic Compounds from PVC flooring, Carpet, and Paint

Abstract: The influence of temperature on the emission rate of volatile organic compounds (VOC) from four indoor materials was investigated in a small dynamic test chamber The materials investigated were two carpets, a PVC flooring and a paint; the temperature range investigated was 23-50°C The general trend was an increased initial emission rate and an increased decay rate with increasing temperature The total emitted mass from paint is independent of temperature which means that bake-out is expected to be successful The total emitted mass of the carpets and the PVC flooring increased with temperature, which suggests an influence of chemical reactions In these cases, bake-out periods of a few days may be unsuccessful and the exposure of the population may be underestimated when using data from experiments performed at the (lower) standard temperature © Indoor Air (1997)

Substrate Effects on VOC Emissions from a Latex Paint

Abstract: The effects of two substrates - a stainless steel plate and a gypsum board - on the volatile organic compound (VOC) emissions from a latex paint were evaluated by environmental chamber tests. It was found that the amount of VOCs emitted from the painted stainless steel was 2 to 10 times more than that from the painted gypsum board during the 2-week test period. The dominant chemical species emitted were also different between the two substrates. Data analysis indicated that most VOC emissions from the painted stainless steel occurred in the first 100 h via a fast, evaporation-like process. On the other hand, the majority of the gypsum board VOCs were emitted in a later stage via a slow, diffusion-controlled process. There were measurable emissions of VOCs 11 months after paint application on the gypsum board. It is suggested that, instead of the routinely used substrates such as stainless steel plates, real substrates such as wood or gypsum board should be used for the evaluation of emissions in indoor environments.

Air Change Effectiveness and Pollutant Removal Efficiency During Adverse Mixing Conditions

Abstract: The air change effectiveness (ACE), an indicator of the indoor airflow pattern, was measured in twenty-six laboratory experiments. Ventilation air was supplied through inductiontype diffusers located in the ceiling and removed through a ceiling-mounted return grille. The tracer gas stepup measurement procedure was employed. In five of the experiments, pollutant removal efficiencies were also measured for simulated pollutant emissions from the floor covering and for simulated emissions from occupants. In experiments with heated supply air, supply air flow rates typical of the minimum supply flow rates of VAV ventilation systems, and 100% outside air, the ACE ranged from 0.69 to 0.89. These results indicate that significant short circuiting of ventilation air between the supply air diffuser and return air grille does occur under these adverse conditions. Mechanical recirculation of air, such that the supply air contained approximately 50% outside air, increased the ACE by about 0.05. When the supply air was cooled, the ACE ranged from 0.99 to 1.15, adding to existing evidence that short circuiting is rarely a problem when the building is being cooled. The pollutant removal efficiency for simulated pollutant emissions from the floor covering (PREfloor)was strongly correlated with ACE (R 2 = 0.98) and the values of PREfloor were within approximately 0.1 of the values of ACE. The pollutant removal efficiency for simulated pollutant emissions by occupants varied between workstations and was not as well correlated with the ACE.

Patterns in Volatile Organic Compounds in Dust from Moldy Buildings

Abstract: Of the ca. 80 volatile organic compounds (VOCs) identified from moldy building materials, 40 were identified as possible microbial metabolites or their derivatives. Thermal desorption of dust from visibly mold-contaminated rooms resulted in the identification of 55 tentative microbial VOCs (MVOCs). Principal component analysis of peak areas for 20 W O C s from dust samples allowed the classification of rooms according to their contamination by mold growth. Bacterial flora in the dust was similar for mold-contaminated and control rooms and only a few actinomycete colonies were observed. Mold flora in dust from moldy rooms was dominated by Penicillium commune(palitans), P. chrysogenum and Aspergillus versicolor. Some MVOCs (or their derivatives) from moldy building materials were also identified in dust from mold-infested rooms and from pure cultures of the three dominant mold species grown on a rich laboratory substrate.

The Behaviour of Pyrethroids Indoors: A Model Study

Abstract: Pest control agents containing three different formulations of the pyrethroids permethrin and deltamethrin and/or pyrethrines and the synergist piperonyl butoxide were applied in a model house simulating indoor pest control. The concentrations of the agents were monitored in the gas phase, on suspended particles, house dust and on furniture surfaces over a period of 24 months. Permethrin and deltamethrin were detected only in the gas phase immediately after application of the agents. High concentrations of deltamethrin (˜2 μg/m3) and permethrin (˜40 μg/m3) were found on suspended particles directly after application. This concentration decreased rapidly within two days (deltamethrin ˜5 ng/m3, permethrin −100 ng/m3) but much more slowly during the following 24 months. In house dust, deltamethrin was observed with initial concentrations of ˜50 mg/kg and permethrin at initial concentrations of 150–800 mg/ kg (depending on the formulation). The concentration levels of both compounds decreased by a factor of ˜10 within the first 12 months but remained almost constant thereafter. Decontamination of the rooms using a commercially available household cleanser has little effect on the pyrethroid concentration found on suspended particles, but leads to a substantial reduction of the contamination level in house dust and on furniture surfaces.

Residential Kitchen Range Hoods – Buoyancy-Capture Principle and Capture Efficiency Revisited

Abstract: A buoyancy-capture principle is firstly revisited as the most important fluid dynamics mechanism in kitchen range hoods. A recent new derivation of the capture efficiency of a kitchen range hood, which eliminates the inconsistencies and inadequacies of existing derivations, shows that the capture efficiency equals the ratio of capture flow rate to total plume flow rate in a confined space. The result is applied here, together with the buoyancy-capture principle, to derive a simple formula for determining capture efficiency. A computational fluid dynamics (CFD) program is adapted to study the capture efficiency of range hoods in a residential kitchen and the predicted results are used to evaluate the accuracy of the simple formula. It is shown that the simple capture efficiency model performs reasonably well for the range hoods considered in this paper.

Nonlinear Least‐Squares Minimization Applied to Tracer Gas Decay for Determining Airflow Rates in a Two‐Zone Building

Abstract: We developed a method based on tracer gas decay measurements to quantify the airflow rates, including the interzonal airflows, in a two-zone building: different tracer gases were simultaneously pulse-injected into each of the two zones and the evolution of the gas concentrations in each zone was measured; theoretical concentration profiles obtained by solving dynamic material-balance equations for two coupled, well-mixed zones were fit to the experimental data using nonlinear least-squares minimization; and estimates of the airflow rates were iteratively refined until a best fit was achieved between the model and the data. We conducted experiments validating the method in two full-sized rooms of a test house. Airflows were controlled using blowers, and mixing was ensured by the use of fans. Airflow rates inferred by the tracer gas technique agreed with imposed airflow rates within an average absolute error of 8%. Results are also reported for two experiments conducted in the same structure under uncontrolled conditions. Goodness-of-fit tests revealed no statistically significant differences between measured tracer gas concentrations and theoretical concentration profiles constructed using the least-squares parameter estimates.

Two Moldy Day‐care Centers: a Follow‐up Study of Respiratory Symptoms and Infections

Abstract: The aim was to study the respiratory symptoms among children exposed to indoor air molds in a day-care environment in Finland. Two day-care centers with a mold problem and two reference day-care centers were included in the study and the health data of the children were collected with a follow-up study of two periods. A total of 229 children 3-7 years old attended the day-care centers. During the first follow-up period, the children in the two day-care centers with mold problems had a significantly increased risk of sore throat, purulent and non-purulent nasal discharge, nasal congestion, hoarseness and common cold. During the second follow-up period, a significantly increased risk of purulent nasal discharge, nasal congestion, hoarseness and cough was observed. Upper respiratory tract symptoms, at least once during the study period, were more prevalent among the children attending mold-problem day-care centers. The mold-exposed children had such symptoms repeatedly or the symptoms were prolonged. In conclusion, in the mold-problem day-care centers, overall morbidity for respiratory symptoms and for common cold increased in comparison with the reference day-care centers.

Growth‐Phase‐Related Production of Potential Volatile‐Organic Tracer Compounds by Moulds on Wood

Abstract: The growth-dependent production of known and new potential tracer compounds for moulds of the genus Penicillium on pine wood is shown. The analytical method used involves diffusive sampling by an adsorbent tube (Tenax-TA), thermal desorption, gas chromatography and a mass selective detector. Mass spectra of identified and unidentified potential tracer compounds are presented. Identified compounds are l-Octene-3-ol, 2-Heptanone, 4-Allylanisole and 3-Methyl-l-butanol. In addition, several other compounds were tentatively identified or recognized in different samples by their retention time and mass spectra. The microbiologically produced volatile organic compounds (MVOC) are produced during different time periods of the mould growth cycle. The impact of these results on screening measurements for houses with mould problems is discussed together with the applicability and need for new and more tracer compounds for mould growth in buildings.

Culturable and Total Fungi in Dust Accumulated in Air Ducts in Single‐Family Houses

Abstract: Fungal spore content in dust accumulated in air ducts was investigated in 24 mechanically ventilated single-family houses of which 15 had also a central air heating system. Dust was collected from the ducts simultaneously with cleaning of the ventilation systems. Besides spore concentrations and flora of culturable fungi, total fungal spore concentrations were determined in dust samples by the aqueous two-phase technique and spore counting with epifluorescence microscopy. Culturable spore concentrations in the dust varied from 104 to 107 CFU/g and total spore concentrations from 107 to 108 spores/g. Total spore concentrations in the duct dust were significantly higher in the air heated houses than in the other mechanically ventilated houses. The difference resulted mainly from a higher proportion of recirculation air and a higher age of the air heated houses. Cladosporium, Penicillium, Aspergillus and yeasts consisted of >90% of fungal flora in the dust. Although total spore concentrations were at the same level both in the exhaust and in the supply ducts in both types of house, culturable fungal spore concentrations were slightly higher in the exhaust ducts than in the supply ducts. The proportion of culturable spores was <5% of total spores in dust accumulated in the ducts.

Perceptual and Psychophysiological Responses of Non-smokers to a Range of Environmental Tobacco Smoke Concentrations

Abstract: To estimate the perceptual, psychophysiological and cognitive impact of environmental tobacco smoke (ETS) on non-smokers, seventeen male never-smokers, ages 21–33, were exposed to five concentrations yielding mean ETS-respirable suspended particles (RSP) levels of 58, 113, 217, 368, and 765 μg/m3. During each 90-minute session, four smokers were seated behind a partition and smoked, when cued, to generate 70-minute exposures. For control exposures, smokers “puffed” on unlit cigarettes. Odor Strength, Annoyance, Overall Acceptance and Eye Irritation at the lowest level were significantly different from control values and the degree of change generally increased monotonically with ETS level. Fatigue was not affected by any ETS level. Odor Strength (rated highest of all attributes at all levels) at the 217 μg/m3 ETS-RSP level was 12.5% of the maximum odor intensity experienced prior to the study. No effect of ETS on information processing was observed. Psychological state and eye blink rate were affected at only the 765 μg/m3 ETS-RSP level. During times when the participants were not completing a questionnaire or test, all ETS levels resulted in a 5–8% decrease in respiratory rate, due largely to an increase in expiratory duration, but no change in minute ventilation. The breathing changes may represent a psychophysiological response mediated by the olfactory system. Non-smokers are aware of ETS at ETS-RSP concentrations as low as 58 μg/m3 (˜80-fold higher than the level typical of current U.S. workplace environments where smoking is permitted) but its sensory impact remains relatively small until ETS-RSP concentrations above 217 μg/m3 are encountered.

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 12420 Bq m-3 and 0.16-0.96 h-l, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated un- certainty is discussed. It was found that differences in radon con- centrations 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 in- door 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-' on average had an indoor radon concentration that was only 50% (0.520.1) of that of the group of houses with air change rates below 0.5 h-l. 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.

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.

Chemical and Biological Evaluation of Building Material Emissions

Abstract: The impact on air quality of the emission of pollutants from freshly conditioned sealant and waterborne paint, and a new carpet was investigated by means of a closed emission system and a high loading factor, i.e. “maximized” test conditions. VOCs were measured. Speciated TVOC values obtained by summation of single VOCs and TVOC (cyclohexane equivalents) values determined by IR spectroscopy were of the same order of magnitude for the carpet and for the sealant. Biological evaluation of the effects of the VOCs was undertaken from the concentrations and the odour and irritation thresholds of each substance. The overall agreements and the mutual supplementation of the results from the TVOC and biological evaluations were apparent, suggesting that both approaches should be part of the evaluation of emissions from building materials. Also the mouse bioassay (ASTM, 1984) was used for evaluation of the irritants emitted. Chemical emission testing and the use of established lists of irritation thresholds appear to be more cost-effective, due to the low sensitivity of the bioassay. This approach was demonstrated with 2-butanone oxime (emitted from the sealant). The same type of approach may be used in relation to odour and hazard identification. However, human and animal tests are necessary in cases where biological data are lacking or where the chemical emission is unknown.

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.

Human Exposure to Airborne Pesticides in Homes Treated with Wood Preservatives

Abstract: In rooms where pesticides were applied, air was analysed for its biocide content. Inhabitants of investigated homes attributed their health complaints to pesticide exposure in their homes. Airborne pesticides originating from wood preservatives were sampled on polyurethane foams or Tenax TA and analysed after solvent desorption by HRGC with different types of detector. In investigated homes, concentrations of diazinon, phenthoate, phoxim, propoxur, dichlofluanid, endosulfan, permethrin and tributyltinoxide were found between ≤0.002 and 0.347 μg/m3. In one home, four years after pest control, chlorpyrifos amounted to 0.515 μg/m3. Permethrin emission from a wool carpet ranged between 0.013 and 0.060 μg/m3. Vacuum cleaning for ten minutes increased airborne permethrin up to 0.096 μg/m3. In house dust, diazinon, phenthoate and permethrin were determined in concentrations of 0.60 ≤g/g, 181.00 pg/g and 0.14 μg/g dust, respectively. Estimated inhaled pesticides ranged between ≤0.04 and 10.3 μg/day. Dust ingestion contributed to 0.03–36.2 μg/day. Pesticide intake through inhalation and dust ingestion was estimated to range between 4% and 120% of the ADI-value. Based on today's knowledge, toxic effects are not anticipated.

The Acute Effect of Environmental Tobacco Smoke Exposure on Asthmatics: Studies with a Dynamic Challenge Chamber

Abstract: To determine the acute effects of environmental tobacco smoke on respiratory tract lung function, 130 asthmatics and 28 non-asthmatics were exposed up to 4 hours to side stream environmental tobacco smoke (SS-ETS) in a dynamic challenge chamber. The vast majority of the subjects exposed to SS-ETS reported upper respiratory and ocular irritant symptoms; the prevalence of these symptoms was not significantly associated with any particular study groups analyzed, or with the self-perception of tobacco smoke allergy by the study subject. All 28 SS-ETS-exposed non-asthmatics had no significant change in lung function, while 26/130 asthmatics demonstrated a significant drop in pulmonary function (FEV1≥20% decline), generally within 90 to 240 minutes after start of exposure. Classical late phase bronchoconstriction was not observed up to 24 hours following the challenge. Six/26 reactors had a significant drop in lung function following a sham control challenge, indicating that 20/130 asthmatics had a specific bronchoconstrictive response to SS-ETS. Responses to diminishing levels of SS-ETS demonstrated that some asthmatics can react to levels as low as 0.0128 cigarette – min/m3 (comparable to ETS levels in the homes of many smokers).

The Possible Role of Indoor Radon Reduction Systems in Back-Drafting Residential Combustion Appliances

Abstract: A computational sensitivity analysis was conducted to identify the conditions under which residential active soil depressurization (ASD) systems for indoor radon reduction might most likely exacerbate or create back-drafting of natural-draft combustion appliances. Parameters varied included: house size; normalized leakage area; exhaust rate of exhaust appliances other than the ASD system; and the amount of house air exhausted by the ASD system. Even with a reasonably conservative set of assumptions, it is predicted that ASD systems should not exacerbate or create back- drafting in most of the U.S. housing stock. Only at normalized leakage areas lower than 3 to 4 cm2 (@ 4 Pa) per m2 of floor area should ASD contribute to back-drafting, even in small houses at high ASD exhaust rates (compared to a mean of over 10 cm2/m2 determined from data on over 12,000 U.S. houses). But on the other hand, even with a more forgiving set of assumptions, it is predicted that ASD systems could contribute to back-drafting in some fraction of the housing stock – houses tighter than about 1 to 2 cm2/m2– even in large houses at minimal ASD exhaust rates. It is not possible to use parameters such as house size or ASD system flow rate to estimate reliably the risk that an ASD system might contribute to back-drafting in a given house. Spillage/back-draft testing would be needed for essentially all installations.