title: Relationships of Indoor, Outdoor, and Personal Air (RIOPA). Part I. Collection methods and descriptive analyses.
abstract: This study on the relationships of indoor, outdoor, and personal air (RIOPA) was undertaken to collect data for use in evaluating the contribution of outdoor sources of air toxics and particulate matter (PM) to personal exposure. The study was not designed to obtain a population-based sample, but rather to provide matched indoor, outdoor, and personal concentrations in homes that varied in their proximity to outdoor pollution sources and had a wide range of air exchange rates (AERs). This design allowed examination of relations among indoor, outdoor, and personal concentrations of air toxics and PM across a wide range of environmental conditions; the resulting data set obtained for a wide range of environmental pollutants and AERs can be used to evaluate exposure models. Approximately 100 households with residents who do not smoke participated in each of three cities in distinct locations expected to have different climates and housing characteristics: Elizabeth, New Jersey; Houston, Texas; and Los Angeles County, California. Questionnaires were administered to characterize homes, neighborhoods, and personal activities that might affect exposures. The concentrations of a suite of volatile organic compounds (VOCs) and carbonyl compounds, as well as the fraction of airborne particulate matter with a mass median aerodynamic diameter < or = 2.5 microm (PM2.5), were measured during continuous 48-hour sessions in which indoor, outdoor, and personal air samples were collected simultaneously. During the same 48-hour period, the AER (exchanges/hr; x hr(-1)) was determined in each home, and carbonyl compounds were measured inside vehicle cabins driven by a subset of the participants. In most of the homes, measurements were made twice, during two different seasons, to obtain a wide distribution of AERs. This report presents in detail the data collection methods, quality control measures, and initial analyses of data distributions and relations among indoor, outdoor, and personal concentrations. The results show that indoor sources dominated personal and indoor air concentrations of many measured VOCs and carbonyl compounds. For several measured species, personal concentrations were higher than either indoor or outdoor concentrations, indicating the presence of some sources closely related to personal activities. For some species there were no significant indoor sources in the majority of the homes; thus indoor concentrations were mainly determined by outdoor concentrations in these homes. The range of distributions of air concentrations for the measured VOCs, formaldehyde and acetaldehyde, PM2.5, and AERs were generally consistent with values reported previously in the literature. Thus associations derived from or models based on this data set that may link the influence of outdoor sources with indoor air concentrations of air toxics and PM2.5 can be relevant to other urban settings. The simultaneous measurements of indoor concentrations, outdoor concentrations, AERs, and room volumes allowed the use of a mass balance model, under the steady-state approximation, to mechanistically examine the relative contributions of indoor and outdoor sources to measured indoor concentrations on a home-by-home basis. Estimated indoor source strengths for VOCs and carbonyl compounds varied widely from home to home, consistent with the indoor-outdoor concentration patterns, as shown in scatter plots. The indoor source estimations agreed with published values for PM2.5 and with the general understanding of sources of VOCs and carbonyl compounds. The source strengths reported here, derived from hundreds of homes, are an important contribution to the literature on exposure to air toxics. For the first time for many compounds, these estimates present a cohesive set of measurements across a range of air toxics in paired indoor, outdoor, and personal samples along with AER and questionnaire results that can be used for future analyses of indoor air quality. The estimation of outdoor contributions to measured indoor concentrations provides insights about the relative importance of indoor and outdoor sources in determining indoor concentrations, the main determinant of personal exposure for most of the measured compounds. In this report simple statistical tests mainly of the pooled data were used to analyze differences by sampling site, emission source type, season, home type, and home age. Paired adult-child personal concentrations within the same home were also compared using the pooled data set. These analyses generated some intriguing results that warrant more in-depth investigation in the future.
authors.affiliation: Environmental and Occupational Health Sciences Institute, Piscataway, NJ 08854, USA. weisel@eohsi.rutgers.edu
authors.forename: Clifford P
authors.initials: CP
authors.lastname: Weisel
authors.forename: Junfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Turpin
authors.forename: Maria T
authors.initials: MT
authors.lastname: Morandi
authors.forename: Steven
authors.initials: S
authors.lastname: Colome
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Stock
authors.forename: Dalia M
authors.initials: DM
authors.lastname: Spektor
authors.forename: Leo
authors.initials: L
authors.lastname: Korn
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Winer
authors.forename: Jaymin
authors.initials: J
authors.lastname: Kwon
authors.forename: Qing Yu
authors.initials: QY
authors.lastname: Meng
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Robert
authors.initials: R
authors.lastname: Harrington
authors.forename: Weili
authors.initials: W
authors.lastname: Liu
authors.forename: Adam
authors.initials: A
authors.lastname: Reff
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Alimokhtari
authors.forename: Kishan
authors.initials: K
authors.lastname: Mohan
authors.forename: Derek
authors.initials: D
authors.lastname: Shendell
authors.forename: Jennifer
authors.initials: J
authors.lastname: Jones
authors.forename: L
authors.initials: L
authors.lastname: Farrar
authors.forename: Slivia
authors.initials: S
authors.lastname: Maberti
authors.forename: Tina
authors.initials: T
authors.lastname: Fan
mesh_terms: D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D009930:Organic Chemicals / Q000032:analysis; D010316:Particle Size; D011786:Quality Control; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014481:United States; D014504:Urban Health; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D009930:Organic Chemicals