1. ^aDepartment of Environmental Sciences, Rutgers University, 14 College Farm Rd, New Brunswick, New Jersey 08901, USA
2. ^bEnvironmental and Occupational Health Sciences Institute, 170 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
3. ^cSchool of Public Health, Houston Health Sciences Center, University of Texas, 1200 Hermann Pressler, Houston, Texas 77030, USA
4. ^dIntegrated Environmental Sciences, 5319 University Drive #430, Irvine, California 92612, USA
5. ^eEnvironmental Science and Engineering Program, School of Public Health, University of California, Los Angeles, 650 Charles E. Young Drive, 46-081 CHS, Los Angeles, California 90095, USA
6. ^fRand Co., 1700 Main St., Santa Monica, California 90401, USA

Correspondence: Dr. B.J. Turpin, Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA. Tel.: +1-732-932-9540; Fax: +1-732-932-8644; E-mail: Turpin@aesop.rutgers.edu

Received 1 October 2002; Accepted 2 February 2004; Published online 12 May 2004.

Abstract

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to investigate residential indoor, outdoor and personal exposures to several classes of air pollutants, including volatile organic compounds, carbonyls and fine particles (PM_2.5). Samples were collected from summer, 1999 to spring, 2001 in Houston (TX), Los Angeles (CA) and Elizabeth (NJ). Indoor, outdoor and personal PM_2.5 samples were collected at 212 nonsmoking residences, 162 of which were sampled twice. Some homes were chosen due to close proximity to ambient sources of one or more target analytes, while others were farther from sources. Median indoor, outdoor and personal PM_2.5 mass concentrations for these three sites were 14.4, 15.5 and 31.4 g/m³, respectively. The contributions of ambient (outdoor) and nonambient sources to indoor and personal concentrations were quantified using a single compartment box model with measured air exchange rate and a random component superposition (RCS) statistical model. The median contribution of ambient sources to indoor PM_2.5 concentrations using the mass balance approach was estimated to be 56% for all study homes (63%, 52% and 33% for California, New Jersey and Texas study homes, respectively). Reasonable variations in model assumptions alter median ambient contributions by less than 20%. The mean of the distribution of ambient contributions across study homes agreed well for the mass balance and RCS models, but the distribution was somewhat broader when calculated using the mass balance model with measured air exchange rates.