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Atmospheric Environment

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https://www.readbyqxmd.com/read/29632433/sensitivity-analysis-of-the-near-road-dispersion-model-rline-an-evaluation-at-detroit-michigan
#1
Chad W Milando, Stuart A Batterman
The development of accurate and appropriate exposure metrics for health effect studies of traffic-related air pollutants (TRAPs) remains challenging and important given that traffic has become the dominant urban exposure source and that exposure estimates can affect estimates of associated health risk. Exposure estimates obtained using dispersion models can overcome many of the limitations of monitoring data, and such estimates have been used in several recent health studies. This study examines the sensitivity of exposure estimates produced by dispersion models to meteorological, emission and traffic allocation inputs, focusing on applications to health studies examining near-road exposures to TRAP...
May 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/29725240/mutagenic-atmospheres-resulting-from-the-photooxidation-of-aromatic-hydrocarbon-and-no-x-mixtures
#2
Theran P Riedel, David M DeMarini, Jose Zavala, Sarah H Warren, Eric W Corse, John H Offenberg, Tadeusz E Kleindienst, Michael Lewandowski
Although many volatile organic compounds (VOCs) are regulated to limit air pollution and the consequent health effects, the photooxidation products generally are not. Thus, we examined the mutagenicity in Salmonella TA100 of photochemical atmospheres generated in a steady-state atmospheric simulation chamber by irradiating mixtures of single aromatic VOCs, NOx , and ammonium sulfate seed aerosol in air. The 10 VOCs examined were benzene; toluene; ethylbenzene; o -, m -, and p -xylene; 1,2,4- and 1,3,5-trimethylbenzene; m -cresol; and naphthalene...
April 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/29681759/impacts-of-a-large-boreal-wildfire-on-ground-level-atmospheric-concentrations-of-pahs-vocs-and-ozone
#3
Gregory R Wentworth, Yayne-Abeba Aklilu, Matthew S Landis, Yu-Mei Hsu
During May 2016 a very large boreal wildfire burned throughout the Athabasca Oil Sands Region (AOSR) in central Canada, and in close proximity to an extensive air quality monitoring network. This study examines speciated 24-h integrated polycyclic aromatic hydrocarbon (PAH) and volatile organic compound (VOC) measurements collected every sixth day at four and seven sites, respectively, from May to August 2016. The sum of PAHs (ΣPAH) was on average 17 times higher in fire-influenced samples (852 ng m-3 , n = 8), relative to non-fire influenced samples (50 ng m-3 , n = 64)...
April 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/29713236/accuracy-and-practicality-of-a-portable-ozone-monitor-for-personal-exposure-estimates
#4
Jessica A Sagona, Clifford Weisel, Qingyu Meng
Accurate measurements of personal exposure to atmospheric pollutants such as ozone are important for understanding health risks. We tested a new personal ozone monitor (POM; 2B Technologies) for accuracy, precision, and ease of use. The POM's measurements were compared to simultaneous ozone measurements from a 2B Model 205 monitor and a ThermoScientific 49i monitor, and multiple POMs were placed side-by-side to check precision. Tests were undertaken in a controlled environmental facility, outdoors, and in a private residence...
February 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/29456452/factors-associated-with-no-2-and-no-x-concentration-gradients-near-a-highway
#5
J Richmond-Bryant, M G Snyder, R C Owen, S Kimbrough
The objective of this research is to learn how the near-road gradient, in which NO2 and NOX (NO + NO2 ) concentrations are elevated, varies with changes in meteorological and traffic variables. Measurements of NO2 and NOX were obtained east of I-15 in Las Vegas and fit to functions whose slopes (dCNO2 /dx and dCNOX /dx, respectively) characterize the size of the near-road zone where NO2 and NOX concentrations from mobile sources on the highway are elevated. These metrics were used to learn about the near-road gradient by modeling dCNO2 /dx and dCNOX /dx as functions of meteorological variables (e...
November 21, 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29681758/ozonolysis-of-%C3%AE-%C3%AE-farnesene-mixture-analysis-of-gas-phase-and-particulate-reaction-products
#6
Mohammed Jaoui, Michael Lewandowski, John H Offenberg, Kenneth S Docherty, Tadeusz E Kleindienst
Atmospheric oxidation of sesquiterpenes has been of considerable interest recently because of their likely contribution to ambient organic aerosol, but farnesene oxidation has been reported in only a few studies and with limited data. In the present study, a detailed chemical analysis of the organic fraction of gas and particle phases originating from the ozonolysis of a mixture of α-farnesene and β-farnesene was carried out in a 14.5 m3 smog chamber. More than 80 organic compounds bearing OH functionality were detected for the first time in this system in the gas and particle phases...
November 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29333080/comparisons-of-traffic-related-ultrafine-particle-number-concentrations-measured-in-two-urban-areas-by-central-residential-and-mobile-monitoring
#7
Matthew C Simon, Neelakshi Hudda, Elena N Naumova, Jonathan I Levy, Doug Brugge, John L Durant
Traffic-related ultrafine particles (UFP; <100 nanometers diameter) are ubiquitous in urban air. While studies have shown that UFP are toxic, epidemiological evidence of health effects, which is needed to inform risk assessment at the population scale, is limited due to challenges of accurately estimating UFP exposures. Epidemiologic studies often use empirical models to estimate UFP exposures; however, the monitoring strategies upon which the models are based have varied between studies. Our study compares particle number concentrations (PNC; a proxy for UFP) measured by three different monitoring approaches (central-site, short-term residential-site, and mobile on-road monitoring) in two study areas in metropolitan Boston (MA, USA)...
November 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29284988/comparing-on-road-real-time-simultaneous-in-cabin-and-outdoor-particulate-and-gaseous-concentrations-for-a-range-of-ventilation-scenarios
#8
Anna Leavey, Nathan Reed, Sameer Patel, Kevin Bradley, Pramod Kulkarni, Pratim Biswas
Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while traveling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM2.5 , particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work...
October 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29545730/no-to-no-2-conversion-rate-analysis-and-implications-for-dispersion-model-chemistry-methods-using-las-vegas-nevada-near-road-field-measurements
#9
Sue Kimbrough, R Chris Owen, Michelle Snyder, Jennifer Richmond-Bryant
The nitrogen dioxide/oxides of nitrogen (NO2 /NOX ) ratio is an important surrogate for NO to NO2 chemistry in dispersion models when estimating NOX impacts in a near-road environment. Existing dispersion models use different techniques and assumptions to represent NO to NO2 conversion and do not fully characterize all of the important atmospheric chemical and mechanical processes. Thus, "real-world" ambient measurements must be analyzed to assess the behavior of NO2 /NOX ratios near roadways. An examination of NO2 /NOX ratio data from a field study conducted in Las Vegas, Nevada (NV), from mid-December, 2008 through mid-December, 2009 provides insights into the appropriateness of assumptions about the NO2 /NOX ratio included in dispersion models...
September 7, 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29773961/an-example-of-aerosol-pattern-variability-over-bright-surface-using-high-resolution-modis-maiac-the-eastern-and-western-areas-of-the-dead-sea-and-environs
#10
Sever Lee, Alpert Pinhas, Lyapustin Alexei, Wang Yujie, Chudnovsky A Alexandra
The extreme rate of evaporation of the Dead Sea (DS) has serious implicatios for the surrounding area, including atmospheric conditions. This study analyzes the aerosol properties over the western and eastern parts of the DS during the year 2013, using MAIAC (Multi-Angle Implementation of Atmospheric Correction) for MODIS, which retrieves aerosol optical depth (AOD) data at a resolution of 1km. The main goal of the study is to evaluate MAIAC over the study area and determine, for the first time, the prevailing aerosol spatial patterns...
September 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/28781568/simultaneously-reducing-co-2-and-particulate-exposures-via-fractional-recirculation-of-vehicle-cabin-air
#11
Heejung S Jung, Michael L Grady, Tristan Victoroff, Arthur L Miller
Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2 ) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle...
July 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29632432/development-of-high-resolution-dynamic-dust-source-function-a-case-study-with-a-strong-dust-storm-in-a-regional-model
#12
Dongchul Kim, Mian Chin, Eric M Kemp, Zhining Tao, Christa D Peters-Lidard, Paul Ginoux
A high-resolution dynamic dust source has been developed in the NASA Unified-Weather Research and Forecasting (NU-WRF) model to improve the existing coarse static dust source. In the new dust source map, topographic depression is in 1-km resolution and surface bareness is derived using the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS). The new dust source better resolves the complex topographic distribution over the Western United States where its magnitude is higher than the existing, coarser resolution static source...
June 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/28959135/exposure-assessment-models-for-elemental-components-of-particulate-matter-in-an-urban-environment-a-comparison-of-regression-and-random-forest-approaches
#13
Cole Brokamp, Roman Jandarov, M B Rao, Grace LeMasters, Patrick Ryan
Exposure assessment for elemental components of particulate matter (PM) using land use modeling is a complex problem due to the high spatial and temporal variations in pollutant concentrations at the local scale. Land use regression (LUR) models may fail to capture complex interactions and non-linear relationships between pollutant concentrations and land use variables. The increasing availability of big spatial data and machine learning methods present an opportunity for improvement in PM exposure assessment models...
February 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29681757/constraints-on-primary-and-secondary-particulate-carbon-sources-using-chemical-tracer-and-14-c-methods-during-calnex-bakersfield
#14
Rebecca J Sheesley, Punith Dev Nallathamby, Jason D Surratt, Anita Lee, Michael Lewandowski, John H Offenberg, Mohammed Jaoui, Tadeusz E Kleindienst
The present study investigates primary and secondary sources of organic carbon for Bakersfield, CA, USA as part of the 2010 CalNex study. The method used here involves integrated sampling that is designed to allow for detailed and specific chemical analysis of particulate matter (PM) in the Bakersfield airshed. To achieve this objective, filter samples were taken during thirty-four 23-hr periods between 19 May and 26 June 2010 and analyzed for organic tracers by gas chromatography - mass spectrometry (GC-MS)...
2017: Atmospheric Environment
https://www.readbyqxmd.com/read/28848374/regionalized-pm2-5-community-multiscale-air-quality-model-performance-evaluation-across-a-continuous-spatiotemporal-domain
#15
Jeanette M Reyes, Yadong Xu, William Vizuete, Marc L Serre
The regulatory Community Multiscale Air Quality (CMAQ) model is a means to understanding the sources, concentrations and regulatory attainment of air pollutants within a model's domain. Substantial resources are allocated to the evaluation of model performance. The Regionalized Air quality Model Performance (RAMP) method introduced here explores novel ways of visualizing and evaluating CMAQ model performance and errors for daily Particulate Matter ≤ 2.5 micrometers (PM2.5) concentrations across the continental United States...
January 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29062264/characteristics-of-pm-2-5-concentrations-across-beijing-during-2013-2015
#16
Stuart Batterman, Lizhong Xu, Feng Chen, Fang Chen, Xuefen Zhong
High concentrations of particulate matter (PM2.5 ) and frequent air pollution episodes in Beijing have attracted widespread attention. This paper utilizes data from the new air pollution network in China to examine the current spatial and temporal variability of PM2.5 at 12 monitoring sites in Beijing over a recent 2-year period (April 2013) to March 2015). The long term (2-year) average concentration was 83 µg·m-3 , well above Chinese and international standards. Across the region, annual average concentrations varied by 20 µg·m-3 (25% of the average level), with lower levels in suburban areas compared to periurban and urban areas, which had similar concentrations...
November 2016: Atmospheric Environment
https://www.readbyqxmd.com/read/27667959/a-bias-in-the-mass-normalized-dtt-response-an-effect-of-non-linear-concentration-response-curves-for-copper-and-manganese
#17
Jessica G Charrier, Alexander S McFall, Kennedy K-T Vu, James Baroi, Catalina Olea, Alam Hasson, Cort Anastasio
The dithiothreitol (DTT) assay is widely used to measure the oxidative potential of particulate matter. Results are typically presented in mass-normalized units (e.g., pmols DTT lost per minute per microgram PM) to allow for comparison among samples. Use of this unit assumes that the mass-normalized DTT response is constant and independent of the mass concentration of PM added to the DTT assay. However, based on previous work that identified non-linear DTT responses for copper and manganese, this basic assumption (that the mass-normalized DTT response is independent of the concentration of PM added to the assay) should not be true for samples where Cu and Mn contribute significantly to the DTT signal...
November 2016: Atmospheric Environment
https://www.readbyqxmd.com/read/27642251/scripted-drives-a-robust-protocol-for-generating-exposures-to-traffic-related-air-pollution
#18
Allison P Patton, Robert Laumbach, Pamela Ohman-Strickland, Kathy Black, Shahnaz Alimokhtari, Paul Lioy, Howard M Kipen
Commuting in automobiles can contribute substantially to total traffic-related air pollution (TRAP) exposure, yet measuring commuting exposures for studies of health outcomes remains challenging. To estimate real-world TRAP exposures, we developed and evaluated the robustness of a scripted drive protocol on the NJ Turnpike and local roads between April 2007 and October 2014. Study participants were driven in a car with closed windows and open vents during morning rush hours on 190 days. Real-time measurements of PM2...
October 2016: Atmospheric Environment
https://www.readbyqxmd.com/read/27795692/ultrafine-particle-size-as-a-tracer-for-aircraft-turbine-emissions
#19
Erin A Riley, Timothy Gould, Kris Hartin, Scott A Fruin, Christopher D Simpson, Michael G Yost, Timothy Larson
Ultrafine particle number (UFPN) and size distributions, black carbon, and nitrogen dioxide concentrations were measured downwind of two of the busiest airports in the world, Los Angeles International Airport (LAX) and Hartsfield-Jackson International Airport (ATL - Atlanta, GA) using a mobile monitoring platform. Transects were located between 5 km and 10 km from the ATL and LAX airports. In addition, measurements were taken at 43 additional urban neighborhood locations in each city and on freeways. We found a 3-5 fold increase in UFPN concentrations in transects under the landing approach path to both airports relative to surrounding urban areas with similar ground traffic characteristics...
August 2016: Atmospheric Environment
https://www.readbyqxmd.com/read/27346977/limonene-ozonolysis-in-the-presence-of-nitric-oxide-gas-phase-reaction-products-and-yields
#20
Jason E Ham, Joel C Harrison, Stephen R Jackson, J R Wells
The reaction products from limonene ozonolysis were investigated using the new carbonyl derivatization agent, O - tert -butylhydroxylamine hydrochloride (TBOX). With ozone (O3 ) as the limiting reagent, five carbonyl compounds were detected. The yields of the carbonyl compounds are discussed with and without the presence of a hydroxyl radical (OH•) scavenger, giving insight into the influence secondary OH radicals have on limonene ozonolysis products. The observed reaction product yields for limonaketone (LimaKet), 7-hydroxyl-6-oxo-3-(prop-1-en-2-yl)heptanal (7H6O), and 2-acetyl-5-oxohexanal (2A5O) were unchanged suggesting OH• generated by the limonene + O3 reaction does not contribute to their formation...
May 2016: Atmospheric Environment
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