Spatial Variability of PM<sub>2.5</sub> in Urban Areas in the United States

Pinto, Joseph P.; Lefohn, Allen S.; Shadwick, Douglas S.

doi:10.1080/10473289.2004.10470919

Cited by 191 publications

(120 citation statements)

References 8 publications

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“…However, correlation coefficients of similar value (>0.4) are associated with median COD values that are clearly heterogeneous (approximately 0.4) in the late evening. In general, the maximum COD values (up to 0.88) were associated with site pairs including one of the harbor background locations (either LB1 or SP1, not shown) where the paired number concentration data exhibit the largest difference as has been noted by others (Pinto et al 2004). Minimum COD values (<0.1) implying spatial homogeneity were associated with pairs located close together or with similar sources (the LB2-LB3 pair, Figure 11).…”

Section: Total Particle Number Concentrationsmentioning

confidence: 81%

“…Most maximum values reported in California and at other locations in the United States and the world were on the order about 0.2 and less (Pinto et al 2004;Kim et al 2005;Wilson et al 2006). Overall, these results imply a fair amount of spatial homogeneity between the mass concentrations measured.…”

Section: Discussionmentioning

confidence: 99%

“…CODs larger than 0.2 can be considered heterogeneous (Wilson et al 2005). CODs have been used to quantify the variability in PM 2.5 and PM 10 mass concentrations between specific site pairs in several studies-for example in the Los Angeles region where CODs varied from 0.07-0.48 (Pinto et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Further, the presumption that one measurement is representative of concentrations across the entire region of interest may not be valid (Wilson et al 2005;Pinto et al 2004). These two issues can lead to exposure misallocation and introduce bias and considerable uncertainty into exposure assessments (Wilson et al 2005;Wilson and Zawar-Reza 2006).…”

Section: Introductionmentioning

confidence: 99%

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Intra-Community Variability in Total Particle Number Concentrations in the San Pedro Harbor Area (Los Angeles, California)

Moore

Krudysz

Pakbin

et al. 2009

Aerosol Science and Technology

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Recent evidence links elevated ultrafine particle (UFP) concentrations with adverse health effects, but exposure assessments based upon PM 2.5 mass concentrations may be misleading. In order to better understand and quantify intra-community variability in UFP concentrations, a dense network of 14 monitoring sites Address correspondence to Constantinos Sioutas, Department of Civil and Environmental Engineering, University of Southern California, 3920 South Vermont Avenue, KAP 210 MC 2531, Los Angeles, CA 90089, USA. E-mail: sioutas@usc.edu cle number concentrations. For sites within a few km of each other, simultaneous particle number concentrations can vary up to a factor of 10 (<10,000 cm −3 up to 90,000 cm −3 for hourly averages calculated by month). The median hourly correlation coefficient (r) across all sites was modest and varied from 0.3 to 0.56. Specific site locations, particularly proximity to roadways used for goods movement, strongly affect observations. Clear diurnal and seasonal patterns are evident in the data. A diurnal pattern associated with high HDDV volumes and goods movement was identified. Coefficients of Divergence calculated for the site pairs suggest moderate heterogeneity overall (median study COD ≈ 0.35). The intra-urban variability observed in this study is comparable to and exceeds the inter-urban variability observed in a previous study in Los Angeles. UFP concentrations can vary considerably on short spatial scales in source-rich environments strongly influencing the accuracy of exposure assessments.

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Section: Total Particle Number Concentrationsmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Intra-Community Variability in Total Particle Number Concentrations in the San Pedro Harbor Area (Los Angeles, California)

Moore

Krudysz

Pakbin

et al. 2009

Aerosol Science and Technology

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“…The third type of error, which may be called ecologic-level exposure error, has to do with the spatial/temporal uniformity of temporal fluctuations of air pollution. A few past studies have previously examined this type of error (e.g., Ito et al, 2001Ito et al, , 2005Pinto et al, 2004). Examining the variability and effects of this ecologic-level exposure error across pollutants and models is the primary focus of this analysis.…”

Section: Discussionmentioning

confidence: 99%

Characterization of PM2.5, gaseous pollutants, and meteorological interactions in the context of time-series health effects models

Ito

Thurston

Silverman

2007

J Expo Sci Environ Epidemiol

158

102

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Associations of particulate matter (PM) and ozone with morbidity and mortality have been reported in many recent observational epidemiology studies. These studies often considered other gaseous co-pollutants also as potential confounders, including nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), and carbon monoxide (CO). However, because each of these air pollutants can have different seasonal patterns and chemical interactions, the estimation and interpretation of each pollutant's individual risk estimates may not be straightforward. Multi-collinearity among the air pollution and weather variables also leaves the possibility of confounding and over-or under-fitting of meteorological variables, thereby potentially influencing the health effect estimates for the various pollutants in differing ways. To investigate these issues, we examined the temporal relationships among air pollution and weather variables in the context of air pollution health effects models. We compiled daily data for PM less than 2.5 mm (PM 2.5 ), ozone, NO 2 , SO 2 , CO, temperature, dew point, relative humidity, wind speed, and barometric pressure for New York City for the years 1999-2002. We conducted several sets of analyses to characterize air pollution and weather data interactions, to assess different aspects of these data issues: (1) spatial/temporal variation of PM 2.5 and gaseous pollutants measured at multiple monitors; (2) temporal relationships among air pollution and weather variables; and (3) extent and nature of multi-collinearity of air pollution and weather variables in the context of health effects models. The air pollution variables showed a varying extent of intercorrelations with each other and with weather variables, and these correlations also varied across seasons. For example, NO 2 exhibited the strongest negative correlation with wind speed among the pollutants considered, while ozone's correlation with PM 2.5 changed signs across the seasons (positive in summer and negative in winter). The extent of multi-collinearity problems also varied across pollutants and choice of health effects models commonly used in the literature. These results indicate that the health effects regression need to be run by season for some pollutants to provide the most meaningful results. We also find that model choice and interpretation needs to take into consideration the varying pollutant concurvities with the model co-variables in each pollutant's health effects model specification. Finally, we provide an example for analysis of associations between these air pollutants and asthma emergency department visits in New York City, which evaluate the relationship between the various pollutants' risk estimates and their respective concurvities, and discuss the limitations that these results imply about the interpretability of multi-pollutant health effects models.

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Intercomparison of field measurements of nitrous acid (HONO) during the SHARP campaign

et al. 2014

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Because of the importance of HONO as a radical reservoir, consistent and accurate measurements of its concentration are needed. As part of SHARP (Study of Houston Atmospheric Radical Precursors), time series of HONO were obtained by six different measurement techniques on the roof of the Moody Tower at the University of Houston. Techniques used were long path differential optical absorption spectroscopy (DOAS), stripping coil‐visible absorption photometry (SC‐AP), long path absorption photometry (LOPAP®), mist chamber/ion chromatography (MC‐IC), quantum cascade‐tunable infrared laser differential absorption spectroscopy (QC‐TILDAS), and ion drift‐chemical ionization mass spectrometry (ID‐CIMS). Various combinations of techniques were in operation from 15 April through 31 May 2009. All instruments recorded a similar diurnal pattern of HONO concentrations with higher median and mean values during the night than during the day. Highest values were observed in the final 2 weeks of the campaign. Inlets for the MC‐IC, SC‐AP, and QC‐TILDAS were collocated and agreed most closely with each other based on several measures. Largest differences between pairs of measurements were evident during the day for concentrations < ~100 parts per trillion (ppt). Above ~ 200 ppt, concentrations from the SC‐AP, MC‐IC, and QC‐TILDAS converged to within about 20%, with slightly larger discrepancies when DOAS was considered. During the first 2 weeks, HONO measured by ID‐CIMS agreed with these techniques, but ID‐CIMS reported higher values during the afternoon and evening of the final 4 weeks, possibly from interference from unknown sources. A number of factors, including building related sources, likely affected measured concentrations.

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Spatial Variability of PM_2.5 in Urban Areas in the United States

Cited by 191 publications

References 8 publications

Intra-Community Variability in Total Particle Number Concentrations in the San Pedro Harbor Area (Los Angeles, California)

Intra-Community Variability in Total Particle Number Concentrations in the San Pedro Harbor Area (Los Angeles, California)

Characterization of PM2.5, gaseous pollutants, and meteorological interactions in the context of time-series health effects models

Intercomparison of field measurements of nitrous acid (HONO) during the SHARP campaign

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Spatial Variability of PM2.5 in Urban Areas in the United States

Cited by 191 publications

References 8 publications

Intra-Community Variability in Total Particle Number Concentrations in the San Pedro Harbor Area (Los Angeles, California)

Intra-Community Variability in Total Particle Number Concentrations in the San Pedro Harbor Area (Los Angeles, California)

Characterization of PM2.5, gaseous pollutants, and meteorological interactions in the context of time-series health effects models

Intercomparison of field measurements of nitrous acid (HONO) during the SHARP campaign

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Spatial Variability of PM_2.5 in Urban Areas in the United States