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

Abstract

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.