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Atmospheric Environment

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https://www.readbyqxmd.com/read/30061791/oxidative-potential-of-ambient-particulate-matter-in-beirut-during-saharan-and-arabian-dust-events
#1
Christopher Lovett, Mohammad H Sowlat, Najat A Saliba, Alan L Shihadeh, Constantinos Sioutas
In this study, we examine the oxidative potential of airborne particulate matter (PM) in Beirut, Lebanon, as influenced by dust events originating in the Sahara and Arabian deserts. Segregated fine (< 2.5 μm) and coarse (2.5-10 μm) PM samples collected during dust events, as well as during non-dust periods, were analyzed for chemical composition, and the in vitro alveolar macrophage (AM) assay was utilized to determine the oxidative potential of both types of samples. We performed Spearman rank-order correlation analysis between individual chemical components and the oxidative potential of PM to examine the impact of the changes in PM chemical composition due to the occurrence of dust events on overall PM oxidative potential...
September 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/30147428/numerical-analysis-of-pollutant-dispersion-around-elongated-buildings-an-embedded-large-eddy-simulation-approach
#2
H Foroutan, W Tang, D K Heist, S G Perry, L H Brouwer, E M Monbureau
High fidelity, scale-resolving numerical simulations of flow and pollutant dispersion around several elongated isolated buildings are presented in this paper. The embedded large eddy simulation (ELES) is used to model flow and concentration fields for six test cases with various source-building geometries. Specifically, the influence of building aspect ratio, wind direction, and source location is examined with these cases. Results obtained from the present ELES model are evaluated using available wind tunnel measurements, including those of streamwise and spanwise velocities, turbulent kinetic energy, and streamwise, lateral, and spanwise pollutant concentrations...
August 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/29632433/sensitivity-analysis-of-the-near-road-dispersion-model-rline-an-evaluation-at-detroit-michigan
#3
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
#4
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
#5
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/29808078/source-characterization-and-exposure-modeling-of-gas-phase-polycyclic-aromatic-hydrocarbon-pah-concentrations-in-southern-california
#6
Shahir Masri, Lianfa Li, Andy Dang, Judith H Chung, Jiu-Chiuan Chen, Zhi-Hua Tina Fan, Jun Wu
Airborne exposures to polycyclic aromatic hydrocarbons (PAHs) are associated with adverse health outcomes. Because personal air measurements of PAHs are labor intensive and costly, spatial PAH exposure models are useful for epidemiological studies. However, few studies provide adequate spatial coverage to reflect intra-urban variability of ambient PAHs. In this study, we collected 39-40 weekly gas-phase PAH samples in southern California twice in summer and twice in winter, 2009, in order to characterize PAH source contributions and develop spatial models that can estimate gas-phase PAH concentrations at a high resolution...
March 2018: Atmospheric Environment
https://www.readbyqxmd.com/read/29713236/accuracy-and-practicality-of-a-portable-ozone-monitor-for-personal-exposure-estimates
#7
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/30220859/the-reduction-of-summer-sulfate-and-switch-from-summertime-to-wintertime-pm-2-5-concentration-maxima-in-the-united-states
#8
Elizabeth A W Chan, Brett Gantt, Stephen McDow
Exposure to particulate matter air pollution with a nominal mean aerodynamic diameter less than or equal to 2.5 μm (PM2.5 ) has been associated with health effects including cardiovascular disease and death. Here, we add to the understanding of urban and rural PM2.5 concentrations over large spatial and temporal scales in recent years. We used high-quality, publicly-available air quality monitoring data to evaluate PM2.5 concentration patterns and changes during the years 2000-2015. Compiling and averaging measurements collected across the U...
December 2, 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29456452/factors-associated-with-no-2-and-no-x-concentration-gradients-near-a-highway
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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/30147427/regional-and-hemispheric-influences-on-temporal-variability-in-baseline-carbon-monoxide-and-ozone-over-the-northeast-us
#18
Y Zhou, H Mao, K Demerjian, C Hogrefe, J Liu
Interannual variability in baseline carbon monoxide (CO) and ozone (O3 ), defined as mixing ratios under minimal influence of recent and local emissions, was studied for seven rural sites in the Northeast US over 2001 - 2010. Annual baseline CO exhibited statistically significant decreasing trends (-4.3 - -2.3 ppbv yr-1 ), while baseline O3 did not display trends at any site. In examining the data by season, wintertime and springtime baseline CO at the two highest sites (1.5 km and 2 km asl) did not experience significant trends...
2017: Atmospheric Environment
https://www.readbyqxmd.com/read/30147426/does-temperature-nudging-overwhelm-aerosol-radiative-effects-in-regional-integrated-climate-models
#19
Jian He, Timothy Glotfelty, Khairunnisa Yahya, Kiran Alapaty, Shaocai Yu
Nudging (data assimilation) is used in many regional integrated meteorology-air quality models to reduce biases in simulated climatology. However, in such modeling systems, temperature changes due to nudging could compete with temperature changes induced by radiatively active and hygroscopic short-lived tracers leading to two interesting dilemmas: when nudging is continuously applied, what are the relative sizes of these two radiative forces at regional and local scales? How do these two forces present in the free atmosphere differ from those present at the surface? This work studies these two issues by converting temperature changes due to nudging into pseudo radiative effects (PRE) at the surface (PRE_sfc), in troposphere (PRE_atm), and at the top of atmosphere (PRE_toa), and comparing PRE with the reported aerosol radiative effects (ARE)...
2017: Atmospheric Environment
https://www.readbyqxmd.com/read/30078987/dynamic-evaluation-of-two-decades-of-wrf-cmaq-ozone-simulations-over-the-contiguous-united-states
#20
Marina Astitha, Huiying Luo, S Trivikrama Rao, Christian Hogrefe, Rohit Mathur, Naresh Kumar
Dynamic evaluation of the fully coupled Weather Research and Forecasting (WRF)- Community Multi-scale Air Quality (CMAQ) model ozone simulations over the contiguous United States (CONUS) using two decades of simulations covering the period from 1990 to 2010 is conducted to assess how well the changes in observed ozone air quality are simulated by the model. The changes induced by variations in meteorology and/or emissions are also evaluated during the same timeframe using spectral decomposition of observed and modeled ozone time series with the aim of identifying the underlying forcing mechanisms that control ozone exceedances and making informed recommendations for the optimal use of regional-scale air quality models...
2017: Atmospheric Environment
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