Characterization of Personal, Indoor, and Outdoor Exposures to Particulate Matter and Its Composition in New York City and Seattle

Abstract

WM2-O-06 Introduction: Few studies have investigated the composition of particulate matter (PM) in indoor microenvieonments and for personal exposures. Two COPD panel studies were conducted in New York City (NYC) and Seattle to characterize the interrelationship among outdoor, indoor and personal PM concentrations. Methods: In the NYC panel, subjects were followed for 12 consecutive days both in a summer and a winter season (July 2000 to January 2001), while in the Seattle panel, subjects were followed in a winter season (October 2002 to March 2003). Concentrations of PM10 and PM2.5 at their residential outdoor, their residential indoor, a central-monitoring-site, and at their personal breathing zones were measured during 24 hours each day. Elemental composition of the PM samples were measured using x-ray fluorescence (XRF), and elemental carbon contents were estimated using reflectance measurements. Indoor-outdoor-personal concentration correlations were investigated. Multivariate factor analysis-based source apportionment techniques were applied to identify contributing sources each day. Results: For NYC, 176 personal and 366 indoor-outdoor paired PM samples were collected from 9 subjects; for Seattle, 142 personal and 320 indoor-outdoor paired PM samples were collected from 15 subjects. Personal PM10 mass concentrations were 2 times higher for the NYC cohort than for the Seattle cohort (71.4, 52.9, and 23.3 μg/m3, for NYC summer, NYC winter and Seattle winter, respectively). Considerable intersubject variability of the indoor-outdoor correlations were found by season and by geographic locations (r = −0.4 to 0.9, r = 0.1 to 0.7, and r = 0 to 0.9, for NYC summer, NYC winter, and Seattle winter, respectively). In NYC, the identified outdoor sources included soil, oil combustion, transported aerosol, and incineration. In Seattle, soil, marine aerosol, and wood combustion were identified outdoors. In both cities, indoor PM was influenced by outdoor sources, such as oil combustion, and by personal activity sources, such as aerosol generated from inhalation therapy. Discussion: We found different outdoor sources in NYC and Seattle, and indoor PM was associated with outdoor sources and personal activities. The preliminary results suggest that using elemental contents data can provide better characterization of interrelationships of outdoor, indoor, and personal PM concentrations. The detailed quantitative contribution of each source to total PM mass and the contribution of outdoor and indoor sources to personal exposure, and their interrelationships at each city, will be presented at the meeting.