Building-related Symptoms Research Articles

Outdoor Ozone Modifies Effects of Air Filter Medium on Building-Related Symptoms in the Base Study

ISEE-782 Objective: Used (particle-loaded) ventilation air filters have been shown to reduce indoor environmental quality and worker performance and to increase symptoms, with effects stronger after reaction of filters with ozone. We analyzed data from the US EPA Building Assessment Survey and Evaluation (BASE) study to determine if ozone interacts with specific filter materials in affecting building-related symptoms (BRS). Materials and Methods: We analyzed a 34-building subset (with only 1 filter material) from the 100-building BASE study, to determine the separate and joint associations of filter material [polyester/synthetic (PS) or fiberglass (FG)] and outdoor ozone concentration (above/below the median, 67.6 μg/m3) with BRS. Using logistic regression models and general estimating equations adjusting for environmental, building, and personal confounders, we estimated adjusted odds ratios (ORs) and 95% confidence intervals for the association of filter material, ozone, and filter material ozone with BRS. Results: Relative to FG+low ozone, PS alone or high ozone alone each had significant (P < 0.05) associations with fatigue/difficulty concentrating (ORs = 1.93, 1.54, respectively). However, joint exposure to both PS+high ozone, relative to FG+low ozone, had significant relationships with lower and upper respiratory, cough, eye, fatigue, and headache BRS (ORs ranged from 2.26–5.90). Joint ORs for PS+high ozone for lower and upper respiratory and headache BRS were much greater than multiplicative, with interaction P-values <0.10. Estimates of attributable risk proportions suggest that, assuming the associations found represented unbiased, directly causal relationships, removing both risk factors (PR and high ozone) could reduce specific BRS by approximately 26% to 62%. Conclusions: These findings suggest possible adverse health consequences from chemical interactions between outdoor ozone and PS filters in building. Results need confirmation before recommending changes in building operation. However, if additional research confirms causality, estimates indicate that appropriate filter selection may substantially reduce BRS in buildings, especially in high ozone areas.

Ventilation Rate and Building-Related Symptoms in 100 US Office Buildings—The US EPA Base Study

Ventilation Rate and Building-Related Symptoms in 100 US Office Buildings—The US EPA Base Study

Application of artificial neural networks to predict prevalence of building-related symptoms in office buildings

Artificial neural networks (ANN) were constructed to predict prevalence of building-related symptoms (BRS) of office building occupants. Six indoor air pollutants and four indoor comfort variables were used as input variables to the networks. A symptom metric was used as the measure of BRS prevalence, and employed as the output variable. Pollutant concentration, comfort variable, and occupant symptom data were obtained from the Building Assessment and Survey Evaluation study conducted by the US Environmental Protection Agency, in which all were measured concurrently. Feed-forward networks that employ back-propagation algorithm with momentum term and variable learning rate were used in ANN modeling. Root mean square error and R 2 value of the simple linear regression between observed and predicted output were used as performance measures. Among the constructed networks, the best prediction performance was observed in a one-hidden-layered network with an R 2 value of 0.56 for the test set. All constructed networks except one showed a better performance than the multiple linear regression analysis.

Perceived health and comfort in relation to energy use and building characteristics

Within the European research project Health Optimisation Protocol for Energy-efficient Building (HOPE), 96 apartment buildings and 64 office buildings (of which approximately 75% have been designed to be energy-efficient) were investigated. The building characteristics were assessed according to a checklist during a walk-through survey. Occupant questionnaires were used to determine satisfaction about comfort (thermal visual, acoustical and indoor air quality (IAQ)) and their health (Sick Building Syndrome and allergies). Building-averaged collected data are compared, looking for correlations between building characteristics on one hand, and perceived comfort and health on the other hand. Strong correlations are found between perceived IAQ, thermal, acoustic and lighting comfort, confirming results from other studies. Significant correlations between the perceived comfort and building related symptoms were also found, comfortable and healthier buildings being well distinct from uncomfortable ones. Differences of perceived comfort or health between low- and high-energy buildings show that it is possible to design buildings that are healthy, comfortable and energy efficient. Le projet de recherche européen HOPE a servi de cadre à une enquête qui a porté sur 96 immeubles d'habitation et 64 immeubles de bureaux (dont environ 75% avaient été conçus pour être économes en énergie). Les caractéristiques de ces immeubles ont été évaluées en fonction d'une liste de contrôle au cours d'une étude sur le terrain. Les questionnaires remplis par les occupants ont servi à déterminer leur satisfaction en ce qui concerne le confort (confort thermique, visuel, acoustique et IAQ) et aussi leur santé (syndrome du bâtiment malade et allergies). Les données recueillies ont servi à calculer une moyenne pour les bâtiments et ont été comparées; il s'agissait d'établir des corrélations entre les caractéristiques des bâtiments d'une part et, d'autre part, le confort perçu et la santé. On a constaté de fortes corrélations entre la qualité de l'air intérieur perçu, le confort thermique, acoustique et l'éclairage, ce qui a confirmé les résultats obtenus lors d'autres études. On a également constaté des corrélations significatives entre le confort perçu et des symptômes liés aux bâtiments, des bâtiments plus confortables et plus sains étant bien distincts des bâtiments sans confort. Les différences de confort perçu ou de santé entre bâtiments à faible et à haut rendement énergétique montrent qu'il est possible de concevoir des bâtiments qui sont sains, confortables et efficaces sur le plan de l'énergie. Mots clés: évaluation des bâtiments, confort, efficacité énergétique, environnement intérieur, perception de l'occupant, satisfaction

Prevalence of building‐related symptoms as an indicator of health and productivity

The prevalence of building-related symptoms (BRS) is commonly used to characterize the indoor air quality in office buildings. To analyze the costs of building renovation and the improvement of the indoor environment, it is useful to quantitatively relate the prevalence or intensity of BRS to productivity. The intent of this study is to summarize the links between the BRS and productivity, and demonstrate this linkage in two case buildings. A literature was surveyed for studies that measured simultaneously the prevalence or intensity of BRS and subjectively reported or objectively measured productivity. Case studies in two office environments were performed. An association between the prevalence of BRS and productivity of workers in a call center and in an insurance office were investigated. In the first case study, the productivity was expressed using the direct productivity metrics, namely the number of telephone contacts during active working hours while in the second case, the productivity was assessed by using the data concerning sick leave rates. Employees who report more BRS also have more often absences which relate to indoor environment quality (IEQ). Their productivity is lower than those who have better IEQ in their offices. Despite uncertainties related to the data concerning recorded sick leave and self-reported productivity, the number of studies showing an association between BRS and productivity or sick leave suggests that such a relationship exists. The present case studies also demonstrated an association between the BRS and the direct productivity. Based on the data from the call center, a reduction of 10%-units in the prevalence of general symptoms (such as fatigue, headache, nausea, etc.) corresponded with a gain of 1.5% in performance. Based on the findings in the insurance company, a reduction of 10%-units in the prevalence of irritation symptoms corresponded with a decrease of 0.7% in the short-term absenteeism. A review of 23 studies suggests that a linkage exists between typical BRS and productivity indicators such as task or work performance or absence from work. Quantitative associations between BRS and productivity were demonstrated in two office environments. Quantitative associations between BRS and economic metrics enable cost-benefits analysis.

Multivariate evaluation of VOCs in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not

Volatile organic compounds (VOCs) were sampled in buildings where people with non-specific building-related symptoms perceive health problems and in buildings where they do not. In total, nine persons and 34 buildings were included in the study. The obtained VOC data was evaluated using multivariate methods, to investigate possible systematic differences in air quality of 'problem' and 'non-problem' buildings. All individual compounds were included as variables in a multivariate partial least squares (PLS) data analysis. 'Problem' and 'non-problem' buildings separated into two distinct groups, showing that air samples of the two groups of building were chemically different. The study showed that there was an identifiable systematic difference in the collected VOC data between buildings causing and not causing problems for people with non-specific building-related symptoms (also called sick building syndrome, SBS). This is an important indication that even such volatile organic compounds that can be sampled by commonly used adsorbents are of importance for the presence of such symptoms. By coordination of procedures for sampling and analysis of VOCs in buildings between laboratories, to get large datasets and more general models, the method can become a useful diagnostic measure in evaluating indoor air and to identify chemical compounds and sources that contribute to SBS problems.

Inflammatory potency of dust from the indoor environment and correlation to content of NAGase and fungi

The aim of this study was to analyse the contribution of microbial factors to the inflammatory potency of dust (PD). Floor dust was sampled three times from 12 rooms in two schools. The potency of floor dust was measured as interleukin-8 secretion from the lung epithelial cell line A549 after exposure to dust. Measurements of endotoxin, NAGase activity and cultivable fungi in the dust were made. For endotoxin a difference was found between sampling days and for NAGase a difference was found between the schools. The carpeted staff rooms of the two schools had a significantly higher amount of dust/m 2 and endotoxin/m 2, and the PD/m 2 and NAGase activity/m 2 were also higher than in the classrooms with smooth flooring. The PD/m 2 correlated with all fungal parameters except total cultivable fungi. NAGase/m 2 correlated with PD, endotoxin and cultivable Cladosporium sp. per rarea, and was nearly significantly correlated to total cultivable fungi and Penicillium spp. Therefore; microbiological activity especially from fungi may contribute to the inflammatory potency of floor dust. Carpet flooring may act as a “sink” for microorganisms resulting in a higher inflammatory potency of floor dust, which may reflect building-related symptoms in occupants.

Indicators of Moisture and Ventilation System Contamination in U.S. Office Buildings as Risk Factors for Respiratory and Mucous Membrane Symptoms: Analyses of the EPA BASE Data

We assessed associations between indicators for moisture in office buildings and weekly, building-related lower respiratory and mucous membrane symptoms in office workers, using the U.S. EPA BASE data, collected in a representative sample of 100 U.S. office buildings. We estimated the strength of associations between the symptom outcomes and moisture indicators in multivariate logistic regression models as odds ratios (ORs) and 95% confidence intervals (CI), controlling for potential confounding factors and adjusting for correlation among workers in buildings. This analysis identified associations between building-related symptoms and several indicators of moisture or contamination in office buildings. One set of models showed almost a tripling of weekly building-related lower respiratory symptoms in association with lack of cleaning of the drip pans under air-conditioning cooling coils (OR [CI] = 2.8 (1.2–6.5)). Other models found that lack of cleaning of either drip pans or cooling coils was associated with increased mucous membrane symptoms (OR [CI] = 1.4 (1.1–1.9)). Slightly increased symptoms were also associated with other moisture indicators, especially mucous membrane symptoms and past water damage to building mechanical rooms (OR [CI] = 1.3 (1.0–1.7)). Overall, these findings suggest that the presence of moisture or contamination in ventilation systems or occupied spaces in office buildings may have adverse respiratory or irritant effects on workers. The analysis, however, failed to confirm several risks identified in a previous study, such as condition of drain pans or outdoor air intakes, and other hypothesized moisture risks. Studies with more rigorous measurement of environmental risks and health outcomes will be necessary to define moisture-related risks in buildings.

Influence of Indoor Carbon Dioxide and Volatile Organic Compounds on Building-Related Non-Specific Symptoms

Influence of Indoor Carbon Dioxide and Volatile Organic Compounds on Building-Related Non-Specific Symptoms

Fungal and endotoxin measurements in dust associated with respiratory symptoms in a water-damaged office building

We investigated the associations of fungal and endotoxin levels in office dust with respiratory health in 888 (67% participation) occupants of a water-damaged building. We analyzed floor and chair dusts from 338 workstations for culturable fungi and endotoxin. Based on averages, we ranked each floor of the building as low, medium, or high for occupants' exposure to each of these agents. Multivariate logistic regression models for building-related symptoms included this ranking of fungi and endotoxin, age, gender, race, smoking status, and duration of occupancy. Using floor dust measures, we found significantly increased odds for lower respiratory symptoms [wheeze, chest tightness, attacks of shortness of breath, and attacks of cough: odds ratios (OR) = 1.7 (95% confidence interval (CI): 1.02-2.77) to 2.4 (95% CI: 1.29-4.59)], throat irritation [OR = 1.7, (95% CI: 1.06-2.82)], and rash/itchy skin [OR = 3.0, (95% CI: 1.47-6.19)] in the highest fungal exposure group compared to the lowest, with generally linear exposure-response relationships. Nonlinear relationships were observed for many of these symptoms and endotoxin in floor dust. Interaction models showed that endotoxin modified effects of fungi on respiratory symptoms. Our findings of exposure interactions and exposure-response relationships of fungal and endotoxin with increased risk of building-related symptoms contribute to an understanding of the role of microbial agents in building-related asthma and respiratory and systemic symptoms. Our demonstration of exposure-response relationships between measurements of fungi and/or endotoxin in floor dusts and building-related symptoms implies that microbial agents in floor dust may be a good surrogate measure for dampness-related bioaerosol exposure, considering that measurements of microbial agents in air often fail to demonstrate the associations between exposure and health. In addition, our finding that endotoxin exposure may change the effect of fungal exposure (and vice versa) on respiratory heath suggests that exposure to both fungi and endotoxin should be assessed in epidemiological investigations examining the effect of fungal or endotoxin exposure on respiratory health in indoor environments.

The medical effects of mold exposure

Exposure to molds can cause human disease through several well-defined mechanisms. In addition, many new mold-related illnesses have been hypothesized in recent years that remain largely or completely unproved. Concerns about mold exposure and its effects are so common that all health care providers, particularly allergists and immunologists, are frequently faced with issues regarding these real and asserted mold-related illnesses. The purpose of this position paper is to provide a state-of-the-art review of the role that molds are known to play in human disease, including asthma, allergic rhinitis, allergic bronchopulmonary aspergillosis, sinusitis, and hypersensitivity pneumonitis. In addition, other purported mold-related illnesses and the data that currently exist to support them are carefully reviewed, as are the currently available approaches for the evaluation of both patients and the environment.

Double blind placebo controlled exposure to molds: exposure system and clinical results*

The objective was to develop an experimental setup for human exposure to mold spores, and to study the clinical effect of this exposure in sensitive subjects who had previously experienced potentially building-related symptoms (BRS) at work. From three water-damaged schools eight employees with a positive histamine release test to Penicillium chrysogenum were exposed double- blinded to either placebo, approximately 600,000 spores/m3 air of P. chrysogenum or approximately 350,000 spores/m3 of Trichoderma harzianum for 6 min on three separate days. A statistically significant rise in symptoms from mucous membranes appeared from the 9-graded symptom scale after exposure to T. harzianum or placebo. Dichotomizing the data, whether the participants experienced at least a two-step rise on the symptom scale or not, gave borderline increase in mucous membrane symptoms after exposure to P. chrysogenum. In conclusion this is, to our knowledge, the first study to successfully conduct a human exposure to a highly controlled dose of fungal material aerosolized directly from wet building materials. This short-term exposure to high concentrations of two different molds induced no more reactions than exposure to placebo in eight sensitive school employees. However, a statistical type II error cannot be excluded because of the small sample size. In this double blind, placebo controlled study of mold exposure changes in symptoms, objective measurements and blood samples were small and mostly non-significant, and at the same level as after placebo exposure. The developed exposure system based on the Particle-Field and Laboratory Emission Cell (P-FLEC) makes it possible to deliver a precise and highly controlled dose of mold spores from water-damaged building materials, imitating realistic field exposure conditions. The present experiment is too small to rule out an effect of mold exposure; long-term experimental exposure studies on larger number of subjects are needed.

Molds in floor dust and building-related symptoms among adolescent school children: a problem for boys only?

In this stratified cross-sectional study in eight 'wet' and seven 'dry' schools, 1024 adolescent school children reported potentially building-related symptoms (BRS) in self-administrated questionnaires. From their classrooms dust samples were collected from floors, ventilation ducts, and air; settled dust was collected in cardboard boxes over a period of 5 months. Measurements of temperature, relative humidity and CO2 were performed. BRS were strongly associated with personal factors like recent airway infections, hay fever, asthma and psycho-social work load, but also to molds in floor dust and presence of mechanical ventilation. The association between molds in floor dust and BRS has in stratified analyses shown a strong association among adolescent school boys, and no association among adolescent school girls using multivariable analyses controlling for relevant confounders. In contrast to the menstruating school girls, the symptoms among the small group of not yet menstruating girls were associated with the levels of molds in floor dust. Their symptom prevalences were very similar to those of the boys. This finding makes us suggest a new hypothesis: The higher endogenous estrogen levels of sexually matured adolescent females seems to protect them from the effects of molds in dust, despite their overall higher symptom prevalence. In this cross-sectional epidemiological study of adolescent school children we found independent significant positive associations between building-related symptoms and viable molds in floor dust in boys and non-menstruating girls. In contrast, no such associations were seen among menstruating girls. The identification of these two susceptible groups adds further support the relevance of minimizing sources of dust and mold exposure.

Molds in floor dust, building-related symptoms, and lung function among male and female schoolteachers

Five hundred and twenty-two teachers from 15 public schools, eight 'water-damaged' schools, and seven 'non-damaged' schools with no visible water damage were included in a cross-sectional design. Mold growth was assessed by recording the amount of dust on the floor and in the air in classrooms and the content of a number of mold species in the dust (CFU/g dust). The evaluation of health symptoms included symptoms recorded by questionnaire and spirometry, bronchial challenge, and CO-diffusion capacity. Nasal lavage fluid was analyzed for IL-8 and ECP. Personal and psychosocial factors were included as confounders. In this study population mucus membrane irritation symptoms (MMI) and general symptoms were reported more frequently by women than by men with odds ratios ranging from 1.4 to 2.1. Women's reports of symptoms from mucous membranes and skin and general symptoms were positively associated with mold exposure. Odds ratio for 'difficult to concentrate' after adjustment for confounders was 11.2 (1.4-90.1, 95% CI) at high levels of mold exposure. None of the lung function tests performed in this study were associated with mold exposure, to the 'water damaged' vs. 'non-damaged' classification, or to the symptoms reported. IL-8 and ECP were not associated either. Psychosocial and personal reasons dominate in MMI and general symptoms. Headache and difficulties to concentrate associated with indoor mold exposure, mainly for women. No lung function impairment associated with indoor mold exposure.

Mucous membrane and lower respiratory building related symptoms in relation to indoor carbon dioxide concentrations in the 100-building BASE dataset

Indoor air pollutants are a potential cause of building related symptoms and can be reduced by increasing ventilation rates. Indoor carbon dioxide (CO(2)) concentration is an approximate surrogate for concentrations of occupant-generated pollutants and for ventilation rate per occupant. Using the US EPA 100 office-building BASE Study dataset, we conducted multivariate logistic regression analyses to quantify the relationship between indoor CO(2) concentrations (dCO(2)) and mucous membrane (MM) and lower respiratory system (LResp) building related symptoms, adjusting for age, sex, smoking status, presence of carpet in workspace, thermal exposure, relative humidity, and a marker for entrained automobile exhaust. In addition, we tested the hypothesis that certain environmentally mediated health conditions (e.g., allergies and asthma) confer increased susceptibility to building related symptoms. Adjusted odds ratios (ORs) for statistically significant, dose-dependent associations (P < 0.05) for combined mucous membrane, dry eyes, sore throat, nose/sinus congestion, sneeze, and wheeze symptoms with 100 p.p.m. increases in dCO(2) ranged from 1.1 to 1.2. Building occupants with certain environmentally mediated health conditions were more likely to report that they experience building related symptoms than those without these conditions (statistically significant ORs ranged from 1.5 to 11.1, P < 0.05). These results suggest that provision of sufficient per-person outdoor ventilation air, could significantly decrease prevalence of selected building related symptoms. The observed relationship between indoor minus outdoor CO(2) concentrations and mucous membrane and lower respiratory symptoms suggests that air contaminants are implicated in the etiology of building related symptoms. Levels of indoor air pollutants that are suspected to cause building related symptoms could be reduced by increasing ventilation rates, improving ventilation effectiveness, or reducing sources of indoor air pollutants, if known.

Building-related respiratory symptoms can be predicted with semi-quantitative indices of exposure to dampness and mold

Using a semi-quantitative mold exposure index, the National Institute for Occupational Safety and Health (NIOSH) investigated 13 college buildings to examine whether building-related respiratory symptoms among employees are associated with environmental exposure to mold and dampness in buildings. We collected data on upper and lower respiratory symptoms and their building-relatedness, and time spent in specific rooms with a self-administered questionnaires. Trained NIOSH industrial hygienists classified rooms for water stains, visible mold, mold odor, and moisture using semi-quantitative scales and then estimated individual exposure indices weighted by the time spent in specific rooms. The semi-quantitative exposure indices significantly predicted building-related respiratory symptoms, including wheeze [odds ratio (OR) = 2.3; 95% confidence interval (CI) = 1.1-4.5], chest tightness (OR = 2.2; 95% CI = 1.1-4.6), shortness of breath (OR = 2.7; 95% CI = 1.2-6.1), nasal (OR = 2.5; 95% CI = 1.3-4.7) and sinus (OR = 2.2; 95% CI = 1.2-4.1) symptoms, with exposure-response relationships. We found that conditions suggestive of indoor mold exposure at work were associated with building-related respiratory symptoms. Our findings suggest that observational semi-quantitative indices of exposure to dampness and mold can support action to prevent building-related respiratory diseases. Current air sampling methods have major limitations in assessing exposure to mold and other biological agents that may prevent the demonstration of associations of bioaerosol exposure with health. Our study demonstrates that semi-quantitative dampness/mold exposure indices, based solely on visual and olfactory observation and weighted by time spent in specific rooms, can predict existence of excessive building-related respiratory symptoms and diseases. Relative extent of water stains, visible mold, mold odor, or moisture can be used to prioritize remediation to reduce potential risk of building-related respiratory diseases. From a public health perspective, these observational findings justify action to correct water leaks and repair water damage in order to prevent building-related respiratory diseases. This approach can also be a basis for developing practical building-diagnostic tools for water-incursion.

Performance of three air distribution systems in VOC removal from an area source

Building-related health complaints and symptoms represent a significant occupational health problem. Elevated concentrations of various types of indoor pollutants, frequently associated with inadequate ventilation, have been implicated as a potential cause. The objective of this research is to model and evaluate the performance of several ventilation methods in pollutant removal from indoor environments. Pollutant sources are assumed to be at the floor level, one with a constant emission rate and the other a fast decaying source (volatile organic compound emissions from a wood stain). Three ventilation methods, namely displacement ventilation and two mixing systems using a side grille and ceiling square diffuser respectively are studied. A computer model has been applied to simulate the distributions and the time history of the pollutant concentrations in a mockup office. Experimental data of velocity, temperature, and tracer gas concentration distributions in the chamber with the displacement diffuser are obtained to validate the airflow model. Simulation results show that different ventilation methods affect the pollutant distributions within the room. When the pollutant sources are distributed on the floor and not associated with a heat source or initial momentum, displacement ventilation behaves no worse than perfect mixing ventilation at the breathing zone. Conventional “mixing” diffusers, on the other hand, could perform better or worse than a perfect mixing system. The computer model could be used for selecting appropriate ventilation systems to maximize indoor air quality for occupants.

Molds in floor dust and building-related symptoms in adolescent school children

This stratified cross-sectional epidemiological study included 1053 school children aged 13-17 years. All pupils filled in a questionnaire on building-related symptoms and other relevant health aspects. The following exposure measurements were carried out: room temperature, CO2 level, and relative humidity; building characteristics including mold infestation were assessed, and dust was collected from floors, air, and ventilation ducts during a working day. Dust was examined for endotoxin level, and cultivated for viable molds. We did not find a positive association between building-related symptoms and extent of moisture and mold growth in the school buildings. Five of eight building-related symptoms were significantly and positively associated with the concentration of colony forming units of molds in floor dust: eye irritation, throat irritation, headache, concentration problems, and dizziness. After adjusting for different potentially confounding factors in separate analyses of each symptom, the above-mentioned associations between molds in dust and symptoms were still present, except for concentration problems. However, in none of the analyses was mold exposure the strongest covariate, being secondary to either asthma, hay fever, recent airway infection, or psychosocial factors.

INDOOR CONCENTRATIONS OF FINE AND COARSE PARTICLES AS RISKS FOR BUILDING-RELATED SYMPTOMS AMONG U.S. OFFICE WORKERS

Introduction Concentrations of fine outdoor particles have been associated with increased prevalence of acute symptoms in numerous studies. We assessed relationships between health symptoms in office workers and indoor concentrations of particles, using data collected from a representative sample of 100 U.S. office buildings in the U.S. EPA BASE study. Methods We assessed associations in these office buildings between two types of building-related symptoms (defined as occurring at least weekly and improving when away from the building)-lower respiratory and mucous membrane-and indoor concentrations of fine or coarse particles. Multivariate logistic regression models were used to estimate the odds ratios (ORs) for associations between the two outcomes and quartiles of particle concentrations, adjusted for a variety of person-related and environment-related variables, including potential confounding variables such as characteristics of filtration systems as well as other risk factors for the outcomes. Results Indoor concentrations of fine and coarse particles were very low for all buildings (minimum, median and maximum were, for fine particles, 1.0, 7.2, and 22.5 μg/m3, and for coarse particles, 0.2, 3.9, and 16.3 μg/m3). In unadjusted analyses, indoor fine particles were not associated with either outcome, but the higher quartiles of concentrations of indoor coarse particle were inconsistently associated with elevated risk for both outcomes. In multivariate adjusted models, neither indoor fine nor coarse particles were significantly associated with prevalence of building-related mucus membrane symptoms (p-values = 0.62, 0.52) or lower respiratory symptoms (p-values = 0.74, 0.66). Point estimates for quartiles of indoor fine particle concentrations and building-related lower respiratory symptoms, however, showed a monotonic increase in risk: ORs = 1.0. 1.2, 1.2, 1.4, despite all 95% confidence intervals including 1.0. Discussion The lack of clear associations in these buildings between indoor particle concentrations and building-related symptoms is not surprising, given the low concentrations of particles observed. The suggestion of a positive relationship for indoor fine particles, however, is intriguing. Future analyses will include refinement of models and assessment of relationships within potentially susceptible subgroups such as previously diagnosed asthmatics.

BUILDING-RELATED SYMPTOMS AMONG U.S. OFFICE WORKERS AND RISK FACTORS FOR MOISTURE AND CONTAMINATION

Introduction Moisture and other risks for indoor microbiologic growth have been associated with increased prevalence of symptoms in many studies. We assessed relationships between health symptoms in office workers and risk factors related to moisture and contamination, using data collected from a representative sample of 100 U.S. office buildings in the U.S. EPA BASE study. Methods Analyses assessed associations between three types of buildingrelated symptoms (defined as occurring at least weekly and improving when away from the building)-lower respiratory, mucous membrane, and neurologic-and risk factors for moisture or contamination in these office buildings. Multivariate logistic regression models were used to estimate the strength of associations for these risk factors as odds ratios (ORs) adjusted for personal-level potential confounding variables related to demographics, health, job, and workspace. Results A number of risk factors were associated significantly (e.g., 95% confidence limits excluded 1.0) in adjusted models with small to moderate increases in one or more symptom outcomes. Significantly elevated ORs for mucous membrane symptoms were associated with the following risk factors: presence of humidification system in good condition versus no system present (OR = 1.4); air handler inspection annually versus daily (OR = 1.6); current water damage in the building (OR = 1.2); and less than daily vacuuming in study space (OR = 1.2). Significantly elevated ORs for lower respiratory symptoms were associated with: air handler inspection annually versus daily (OR = 2.0); air handler inspection less than daily but at least semi-annually (OR = 1.6); less than daily cleaning of offices (1.7); and less than daily vacuuming of the study space (OR = 1.4). Only two statistically significant risk factors for neurologic symptoms were identified: presence of any humidification system versus none (OR = 1.3); and less than daily vacuuming of the study space (OR = 1.3). Dirty cooling coils, dirty or poorly draining drain pans, and standing water near outdoor air intakes were not identified as risk factors in these analyses, despite predictions based on previous findings elsewhere, except that very dirty cooling coils were associated with a statistically nonsignificant increase (OR = 1.3, 95% confidence interval = 0.9–2.1) in lower respiratory symptoms Conclusions These preliminary findings suggest that some factors indicating risks for moisture or contamination in office buildings may have adverse effects on respiratory or neurologic health of office workers. Expanded analyses are underway that will include in multivariate models additional potential confounders and risk factors, such as ventilation rate and indoor temperature. Future analyses will also assess risk in susceptible sub-groups such as previously diagnosed asthmatics.