Article

Source apportionment of indoor residential fine particulate matter using land use regression and constrained factor analysis.

Harvard School of Public Health, Department of Environmental Health, Boston, MA, USA.
Indoor Air (Impact Factor: 4.2). 09/2010; 21(1):53-66. DOI: 10.1111/j.1600-0668.2010.00682.x
Source: PubMed

ABSTRACT Source contributions to urban fine particulate matter (PM(2.5) ) have been modelled using land use regression (LUR) and factor analysis (FA). However, people spend more time indoors, where these methods are less explored. We collected 3-4- day samples of nitrogen dioxide and PM(2.5) inside and outside of 43 homes in summer and winter, 2003-2005, in and around Boston, Massachusetts. Particle filters were analysed for black carbon and trace element concentrations using reflectometry, X-ray fluorescence (XRF), and high-resolution inductively coupled mass spectrometry (ICP-MS). We regressed indoor against outdoor concentrations modified by ventilation, isolating the indoor-attributable fraction, and then applied constrained FA to identify source factors in indoor concentrations and residuals. Finally, we developed LUR predictive models using GIS-based outdoor source indicators and questionnaire data on indoor sources. FA using concentrations and residuals reasonably separated outdoor (long-range transport/meteorology, fuel oil/diesel, road dust) from indoor sources (combustion, smoking, cleaning). Multivariate LUR regression models for factors from concentrations and indoor residuals showed limited predictive power, but corroborated some indoor and outdoor factor interpretations. Our approach to validating source interpretations using LUR methods provides direction for studies characterizing indoor and outdoor source contributions to indoor cocentrations. PRACTICAL IMPLICATIONS: By merging indoor-outdoor modeling, factor analysis, and LUR-style predictive regression modeling, we have added to previous source apportionment studies by attempting to corroborate factor interpretations. Our methods and results support the possibility that indoor exposures may be modeled for epidemiologic studies, provided adequate sample size and variability to identify indoor and outdoor source contributions. Using these techniques, epidemiologic studies can more clearly examine exposures to indoor sources and indoor penetration of source-specific components, reduce exposure misclassification, and improve the characterization of the relationship between particle constituents and health effects.

Download full-text

Full-text

Available from: Jane Clougherty, Nov 24, 2014
0 Followers
 · 
90 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: This review offers the reader a wealth of information published between April 2010 and March 2011 concerning analytical endeavours using the range of conventional and hyphenated XRF techniques that encourage the user to ensure the potential for high spectral sensitivity and, where appropriate, spatial resolution is achieved. The development of advanced micro-beam set ups and new X-ray optics driven by third generation synchrotron based XRF techniques provide nano-imaging and the detection of nano-particles on single cells whilst TXRF coupled with GIXRF and GEXRF offer great potential for non-destructive investigations of thin layers on reflecting surfaces as well as depth profiling of implants. A new portable XRF system is described as an alternative for the traditionally applied K-X-ray fluorescence technology for in vivo measurements of lead in bone. Cryogenic cooling of heat sensitive biological samples is offered as a method to mitigate possible damage by the use of the more powerful μ-XRF technique. Other new preparation methods are also reviewed for the presentation and analysis of industrial, environmental and archaeological samples. One of the more unusual contributions available this year in the characterisation and use of industrial minerals showed that a semi-precious stone, amethyst, is more effective at shielding radiation than concrete.
    Journal of Analytical Atomic Spectrometry 10/2011; 26(10):1919-1963. DOI:10.1039/C1JA90038B · 3.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Aircraft departures emit multiple pollutants common to other near-airport sources, making it challenging to determine relative source contributions. While there may not be unique tracers of aircraft emissions, examination of multipollutant concentration patterns in combination with flight activity can facilitate source attribution. In this study, we examine concentrations of continuously monitored air pollutants measured in 2008 near a departure runway at Los Angeles International Airport (LAX), considering single-pollutant associations with landing and takeoff (LTO) of the aircraft (LTO activity, weighted by LTO cycle fuel burn), as well as multipollutant predictors of binary LTO activity. In the single-pollutant analyses, one-minute average concentrations of carbon monoxide, carbon dioxide, nitrogen oxides, and sulfur dioxide are positively associated with fuel burn-weighted departures on the runway proximate to the monitor, whereas ozone is negatively associated with fuel burn-weighted departures. In analyses in which the flight departure is predicted by pollutant concentrations, carbon dioxide and nitrogen oxides are the best individual predictors, but including all five pollutants greatly increases the power of prediction compared to single-pollutant models. Our results demonstrate that air pollution impacts from aircraft departures can be isolated using time-resolved monitoring data, and that combinations of simultaneously measured pollutants can best identify contributions from flight activity.
    Environmental Science & Technology 06/2012; 46(15):8229-35. DOI:10.1021/es3007172 · 5.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Indoor residence times of semivolatile organic compounds (SVOCs) are a major and mostly unavailable input for residential exposure assessment. We calculated residence times for a suite of SVOCs using a fugacity model applied to residential environments. Residence times depend on both the mass distribution of the compound between the "mobile phase" (air and dust particles settled on the carpet) and the "non-mobile phase" (carpet fibers and pad) and the removal rates resulting from air exchange and cleaning. We estimated dust removal rates from cleaning processes using an indoor-particle mass-balance model. Chemical properties determine both the mass distribution and relative importance of the two removal pathways, resulting in different residence times between compounds. We conducted a field study after chlorpyrifos was phased out for indoor use in the U.S. in 2001 to determine the decreases in chlorpyrifos air concentrations over a one year period. A measured average decrease of 18% in chlorpyrifos air concentrations indicates the residence time of chlorpyrifos is expected to be 6.9 years and compares well with model predictions. The estimates from this study provide the opportunity to make more reliable estimates of SVOCs exposure in the indoor residential environment.
    Environmental Science & Technology 12/2012; 47(2). DOI:10.1021/es303316d · 5.48 Impact Factor
Show more

Similar Publications