Associations between respiratory health effects and allergens, fungal and endotoxin in settled dust: relevant units of potential exposure.
Am J Respir Crit Care Med 2003 Apr; 167(7):A501
Many indoor environmental studies analyze settled dust rather than airborne contaminants. These are often expressed per gram of dust. However, expressing concentration per unit area sampled is intuitively preferable as a metric of potential exposure. We investigated relationships between potential exposures to contaminants in settled dust reservoirs and lower respiratory symptoms to examine the relevance of these metrics. Floor and chair dusts were vacuumed from 23 locations in 2 hospitals. Dusts were analyzed for cat allergen (Feld1), extracellular polysaccharides (EPS) for Aspergillus and Penicillium, Beta3-glucans, endotoxin, and culturable fungi. Two potential exposure metrics were used: contaminant per unit mass and per unit area. A respiratory symptoms questionnaire was offered to employees (70% participation rate; N=600). There were moderate positive correlations (r=0.35-0.74) between the two potential exposure metrics for endotoxin, culturable fungi, Beta-glucans and EPS and a strong positive correlation (r=0.89) for Feld1. Feld1 per unit mass had very low correlation with total mass of dust while the other contaminants per unit mass were negatively correlated. In univariate logistic models, lower respiratory symptoms were more significantly associated with culturable fungi, Beta3-glucans and EPS concentrations when expressed per unit area than when expressed per unit mass. Both metrics for Feld1 were significantly associated with lower respiratory symptoms. Our findings indicate that settled dust measures of potential exposure in relation to lower respiratory health effects should be expressed per unit area rather than per unit mass.
Respiratory-system-disorders; Allergens; Fungi; Endotoxins; Dust-particles; Dusts; Particulate-dust; Particulates; Exposure-levels; Environmental-exposure; Airborne-dusts; Airborne-particles; Dust-measurement
Abstract; Conference/Symposia Proceedings
Disease and Injury: Asthma and Chronic Obstructive Pulmonary Disease
American Journal of Respiratory and Critical Care Medicine, 2003 International Conference, The American Thoracic Society, Seattle, WA, May 16-21, 2003