Indoor Source Apportionment in Boston, MA

MARIANTHI-ANNA KIOUMOURTZOGLOU (1), Helen Suh (1)

(1) Department of Environmental Health, Harvard School of Public Health, Boston, MA

     Abstract Number: 200
     Last modified: November 8, 2009

Abstract
Background. As people spend most of their time indoors, it is important to identify indoor sources of PM2.5 and determine the proportion of outdoor PM2.5 that infiltrates indoors in order to better characterize exposures to PM2.5 and its components.

Specific Aims. Our study examines the contribution of sources to indoor PM2.5 and examines the relation of these sources to markers of inflammation.

Methods. Seven-day integrated PM2.5, elemental carbon by reflectance, and elemental concentrations by XRF samples were measured in the homes of 149 participants of the Normative Aging Study (NAS). All homes were located within the greater Boston Area and were sampled between mid-July 2006 and May 2008. Corresponding outdoor concentrations were measured at our central monitoring site located at the Harvard Medical School in downtown Boston. In addition, markers of inflammation were measured at the end of the seven-day sampling period for each NAS subject participating in indoor monitoring. EPA’s Positive Matrix Factorization method (PMF) was used to apportion indoor and outdoor sources of PM2.5. The relation between indoor and outdoor concentrations and their sources was examined using Spearman correlation coefficients and linear regression models that controlled for season and that incorporated housing information. Findings will be related to markers of inflammation measured for this cohort.

Results. Indoor and outdoor concentrations were not correlated for any of the measured species, except for sulfur, for which the Spearman correlation coefficient equaled 0.70. Outdoor PM2.5 was apportioned into seven factors, consistent with secondary PM2.5 (10%), motor vehicles (28%), sea salt (5%), burning oil (4%), crystal dust (15%) and re-suspended dirt particles (~1%). These results are in accordance with results reported previously. Indoors, six factors for PM2.5 were identified, consistent with sources including crystal dust, secondary PM2.5 from outdoors, motor vehicles, re-suspended dust, and cleaning. Housing and personal factors that affect the indoor and outdoor source contributions will be identified, with their impacts on various markers of inflammation examined.