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Growing evidence suggests that inhalation exposure to diesel exhaust, including diesel particulate matter (DPM), causes acute and chronic health effects. As a result, interest in monitoring diesel exhaust has increased. Maps of emissions sources, emissions activity data, and meteorology were combined within a geographic information system (GIS) suitability model to produce a composite map identifying areas where DPM emissions are likely to be high. The results of the GIS model were compared with (i) the locations of existing monitoring sites in Phoenix, Arizona, and (ii) the spatial distribution of population. The results indicate that two existing sites are located in areas where DPM emissions are predicted to be high; however, incorporating meteorology as a factor showed that one site is located upwind of a predicted high DPM area. Consideration of population density showed high density in two areas that appear to be moderately influenced by DPM. Key words: diesel particulate matter (DPM), geographic information system (GIS), suitability modeling. De plus en plus de preuves suggerent que l'exposition a l'inhalation des echappements des dieseis, incluant les matieres particulars diesel, entraine des effets aigus el chroniques sur la sante. L'interel dans la surveillance des echappements diesel a done augmente. Des earles des sources des emissions, des donnees sur les activites d'emissions ainsi que des donnees meteorologiques ont ete combinees a un modele pertinent d'un systeme d'informalion geographique (SIG) afin de produire une carte composite montrant les zones oil les emissions de matieres particulates diesel sont probablement elevees. Les resultats du modele SIG ont ete compares (i) aux emplacements des sites de surveillance existants a Phoenix, en Arizona, et (ii) a la distribution spatiale de la population. Les resultats indiquent que deux sites existants sont situes dans les zones ou les emissions de matieres particulates diesel devraient etre elevees. Toutefois, l' incorporal ion du facteur meteorologie a montre qu'un site est situe en amont d'une zone a emissions de matieres particulates diesel probablement elevees. Le fait de tenir compte de la densite de la population a montre une forte densite dans deux zones qui semblen! etre moderement influencees par les matieres particulates diesel. Mots-cles: matieres particulaires diesel, systeme d'information geographique (SIG). modelesation de la pertinence. [Traduit par la Redaction], Introduction This work was funded by the Arizona Department of Environmental Quality (ADEQ) to support the ADEQ toxics monitoring program. The objective of this work was to use geographic information [...]

ABSTRACT Speciated particulate matter (PM)[.sub.2.5] data collected as part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) program in Phoenix, AZ, from April 2001 through October 2003 were analyzed [...]

ABSTRACT Speciated fine particulate matter ([PM.sub.2.5]) data collected as part of the Speciation Trends Network at four sites in the Midwest (Detroit, MI; Cincinnati, OH; Indianapolis, IN; and Northbrook, IL) [...]

ABSTRACT Air quality data collected in the California Regional [PM.sub.10]/[PM.sub.2.5] Air Quality Study (CRPAQS) are analyzed to qualitatively assess the processes affecting secondary aerosol formation in the San Joaquin Valley [...]

ABSTRACT Air quality monitoring was conducted at a rural site with a tower in the middle of California's San Joaquin Valley (SJV) and at elevated sites in the foothills and [...]

We characterized residential biomass burning contributions to fine particle concentrations via multiple methods at Fyfe Elementary School in Las Vegas, Nevada, during January 2008: with levoglucosan on quartz fiber filters; with water soluble potassium (K+) measured using a particle-into-liquid system with ion chromatography (PILS-IC); and with the fragment C2H4O2+ from an Aerodyne High Resolution Aerosol Mass Spectrometer (HR-AMS). A Magee Scientific Aethalometer was also used to determine aerosol absorption at the UV (370 nm) and black carbon (BC, 880 nm) channels, where UV-BC difference is indicative of biomass burning (BB). Levoglucosan and AMS C2H4O2 + measurements were strongly correlated (r2 = 0.92); K+ correlated well with C2H4O2 + (r2 = 0.86) during the evening but not during other times. While K+ may be an indicator of BB, it is not necessarily a unique tracer, as non-BB sources appear to contribute significantly to K+ and can change from day to day. Low correlation was seen between UV-BC difference and other indicators, possibly because of an overwhelming influence of freeway emissions on BC concentrations. Given the sampling location--next to a twelve-lane freeway--urban-scale biomass burning was found to be a surprisingly large source of aerosol: overnight BB organic aerosol contributed between 26% and 33% of the organic aerosol mass. [ABSTRACT FROM AUTHOR]

In this paper, we discuss a team-taught, debate-style Philosophy of Religion course we designed and taught at the Ohio State University. Rather than tackling the breadth of topics traditionally subsumed under the umbrella of Philosophy of Religion, this course focused exclusively on the nuances of the atheism-theism debate, with the instructors openly identifying as atheist or theist, respectively. After discussing the motivations for designing and teaching such a course, we go on to detail its content and structure. We then examine various challenges and hurdles we faced, as well as some benefits we encountered along the way. Next, we discuss some informal data collected from the students enrolled in the course, some of which suggest some rather surprising outcomes. We conclude with some considerations of the applicability of this style of teaching to other philosophical debates. [ABSTRACT FROM AUTHOR]

Understanding the organic matter/organic carbon (OM/OC) ratio in ambient particulate matter (PM) is critical to achieve mass closure in routine PM measurements, to assess the sources of and the degree of chemical processing organic aerosol particles have undergone, and to relate ambient pollutant concentrations to health effects. Of particular interest is how the OM/OC ratio varies in the urban environment, where strong spatial and temporal gradients in source emissions are common. We provide results of near-roadway high-time-resolution PM1OM concentration and OM/OC ratio observations during January 2008 at Fyfe Elementary School in Las Vegas, NV, 18 m from the U.S. 95 freeway soundwall, measured with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). The average OM/OC ratio was 1.54 (± 0.20 standard deviation), typical of environments with a low amount of secondary aerosol formation. The 2-min average OM/OC ratios varied between 1.17 and 2.67, and daily average OM/OC ratios varied between 1.44 and 1.73. The ratios were highest during periods of low OM concentrations and generally low during periods of high OM concentrations. OM/OC ratios were low (1.52 ± 0.14, on average) during the morning rush hour (average OM = 2.4 µg/m3), when vehicular emissions dominate this near-road measurement site. The ratios were slightly lower (1.46 ± 0.10) in the evening (average OM = 6.3 µg/m3), when a combination of vehicular and fresh residential biomass burning emissions was typically present during times with temperature inversions. The hourly averaged OM/OC ratio peaked at 1.66 at midday. OM concentrations were similar, regardless of whether the monitoring site was downwind or upwind of the adjacent freeway throughout the day, though they were higher during stagnant conditions (wind speed < 0.5 m/sec). The OM/OC ratio generally varied more with time of day than with wind direction and speed. Implications:Day-to-day variability in the fine particle OM/OC ratio is quite large, suggesting that using a fixed OM/OC value in PM mass closure calculations, even one that changes seasonally, may be insufficient to achieve accurate mass closure on individual days. Health studies that rely on OC measurements may under- or overestimate exposure to OM, and converting OC to OM with a fixed OM/OC ratio represents a significant source of uncertainty; thus, air quality managers may not have sufficient information about the importance of OM contributions to PM2.5 to make optimal regulatory decisions. Supplemental Materials:Supplemental materials are available for this paper. Go to the publisher's online edition of theJournal of the Air & Waste Management Association. [ABSTRACT FROM PUBLISHER]

Low-cost sensors can provide insight on the spatio-temporal variability of air pollution, provided that sufficient efforts are made to ensure data quality. Here, 19 AirBeam particulate matter (PM) sensors were deployed from December 2016 to January 2017 to determine the spatial variability of PM 2.5 in Sacramento, California. Prior to, and after, the study, the 19 sensors were deployed and collocated at a regulatory air monitoring site. The sensors demonstrated a high degree of precision during all collocated measurement periods (Pearson R 2 = 0.98 - 0.99 across all sensors), with little drift. A sensor-specific correction factor was developed such that each sensor reported a comparable value. Sensors had a moderate degree of correlation with regulatory monitors during the study (R 2 = 0.60 - 0.68 at two sites). In a multi-linear regression model, the deviation between sensor and reference measurements of PM 2.5 had the highest correlation with dew point and relative humidity. Sensor measurements were used to estimate the PM 2.5 spatial variability, finding an average pairwise coefficient of divergence of 0.22 and a range of 0.14 to 0.33, indicating mostly homogeneous distributions. No significant difference in the average sensor PM concentrations between environmental justice (EJ) and non-EJ communities ( p value = 0.24) was observed.

We examined two near-road monitoring sites where the daily PM 2.5 readings were among the highest of any near-road monitoring location in the U.S. during 2014-2016: Denver, Colorado, in February 2014 and Indianapolis, Indiana, in November 2016. At the Denver site, which had the highest measured U.S. near-road 24-hr PM 2.5 concentrations in 2014, concentrations exceeded the daily National Ambient Air Quality Standards (NAAQS) on three days during one week in 2014; the Indianapolis site had the second-highest number of daily exceedances of any near-road site in 2016 and the highest 3-year average PM 2.5 of any near-road site during 2014-2016. Both sites had hourly pollutant, meteorological, and traffic data available, making them ideal for case studies. For both locations, we compared air pollution observations at the near-road site to observations at other sites in the urban area to calculate the near-road PM 2.5 "increment" and evaluated the effects of changes in meteorology and traffic. The Denver near-road site consistently had the highest PM 2.5 values in the Denver area, and was typically highest when winds were near-downwind, rather than directly downwind, to the freeway. Complex Denver site conditions (near-road buildings and roadway alignment) likely contributed to higher PM 2.5 concentrations. The increment at Indianapolis was also highest under near-downwind, rather than directly downwind, conditions. At both sites, while the near-road site often had higher PM 2.5 concentrations than nearby sites, there was no clear correlation between traffic conditions (vehicle speed, fleet mix) and the high PM 2.5 concentrations.