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Atmospheric Environment

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
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
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
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
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
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
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
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
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
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
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
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
Erin A Riley, LaNae Schaal, Miyoko Sasakura, Robert Crampton, Timothy R Gould, Kris Hartin, Lianne Sheppard, Timothy Larson, Christopher D Simpson, Michael G Yost
Mobile monitoring has provided a means for broad spatial measurements of air pollutants that are otherwise impractical to measure with multiple fixed site sampling strategies. However, the larger the mobile monitoring route the less temporally dense measurements become, which may limit the usefulness of short-term mobile monitoring for applications that require long-term averages. To investigate the stationarity of short-term mobile monitoring measurements, we calculated long term medians derived from a mobile monitoring campaign that also employed 2-week integrated passive sampler detectors (PSD) for NOx, Ozone, and nine volatile organic compounds at 43 intersections distributed across the entire city of Baltimore, MD...
May 2016: Atmospheric Environment
Chad Milando, Lei Huang, Stuart Batterman
PM2.5 concentrations throughout much of the U.S. have decreased over the last 15 years, but emissions and concentration trends can vary by location and source type. Such trends should be understood to inform air quality management and policies. This work examines trends in emissions, concentrations and source apportionments in two large Midwest U.S. cities, Detroit, Michigan, and Chicago, Illinois. Annual and seasonal trends were investigated using National Emission Inventory (NEI) data for 2002 to 2011, speciated ambient PM2...
March 2016: Atmospheric Environment
Marie-Cecile G Chalbot, Priyanka Chitranshi, Gonçalo Gamboa da Costa, Erik Pollock, Ilias G Kavouras
The functional and (13)C isotopic compositions of water-soluble organic carbon (WSOC) in atmospheric aerosol were determined by nuclear magnetic resonance ((1)H-NMR) and isotope ratio mass spectrometry (IRMS) in an urban location in the Southern Mississippi Valley. The origin of WSOC was resolved using the functional distribution of organic hydrogen, δ(13)C ratio, and positive matrix factorization (PMF). Three factors were retained based on NMR spectral bins loadings. Two factors (factors 1 and 3) demonstrated strong associations with the aliphatic region in the NMR spectra and levoglucosan resonances...
March 2016: Atmospheric Environment
Itai Kloog, Meytar Sorek-Hamer, Alexei Lyapustin, Brent Coull, Yujie Wang, Allan C Just, Joel Schwartz, David M Broday
Estimates of exposure to PM2.5 are often derived from geographic characteristics based on land-use regression or from a limited number of fixed ground monitors. Remote sensing advances have integrated these approaches with satellite-based measures of aerosol optical depth (AOD), which is spatially and temporally resolved, allowing greater coverage for PM2.5 estimations. Israel is situated in a complex geo-climatic region with contrasting geographic and weather patterns, including both dark and bright surfaces within a relatively small area...
December 2015: Atmospheric Environment
Meng Wang, Joshua P Keller, Sara D Adar, Sun-Young Kim, Timothy V Larson, Casey Olives, Paul D Sampson, Lianne Sheppard, Adam A Szpiro, Sverre Vedal, Joel D Kaufman
BACKGROUND: Current epidemiologic studies rely on simple ozone metrics which may not appropriately capture population ozone exposure. For understanding health effects of long-term ozone exposure in population studies, it is advantageous for exposure estimation to incorporate the complex spatiotemporal pattern of ozone concentrations at fine scales. OBJECTIVE: To develop a geo-statistical exposure prediction model that predicts fine scale spatiotemporal variations of ambient ozone in six United States metropolitan regions...
December 2015: Atmospheric Environment
Anita Shepherd, Xiaoyuan Yan, Dali Nayak, Jamie Newbold, Dominic Moran, Mewa Singh Dhanoa, Keith Goulding, Pete Smith, Laura M Cardenas
China accounts for a third of global nitrogen fertilizer consumption. Under an International Panel on Climate Change (IPCC) Tier 2 assessment, emission factors (EFs) are developed for the major crop types using country-specific data. IPCC advises a separate calculation for the direct nitrous oxide (N2O) emissions of rice cultivation from that of cropland and the consideration of the water regime used for irrigation. In this paper we combine these requirements in two independent analyses, using different data quality acceptance thresholds, to determine the influential parameters on emissions with which to disaggregate and create N2O EFs...
December 2015: Atmospheric Environment
J-S Youn, E Crosbie, L C Maudlin, Z Wang, A Sorooshian
Aerosol and cloud water measurements of dimethylamine (DMA), the most abundant amine in this study, were conducted in semi-arid (Tucson, Arizona) and marine (Nucleation in California Experiment, NiCE; central coast of California) areas. In both regions, DMA exhibits a unimodal aerosol mass size distribution with a dominant peak between 0.18 and 0.56 μm. Particulate DMA concentrations increase as a function of marine biogenic emissions, sulfate, BVOC emissions, and aerosol-phase water. Such data supports biogenic sources of DMA, aminium salt formation, and partitioning of DMA to condensed phases...
December 2015: Atmospheric Environment
Andres Martinez, Scott N Spak, Nicholas T Petrich, Dingfei Hu, Gregory R Carmichael, Keri C Hornbuckle
Indiana Harbor and Ship Canal (IHSC) in East Chicago is an industrial waterway on Lake Michigan and a source of PCBs to Lake Michigan and the overlying air. We hypothesized that IHSC is an important source of airborne PCBs to surrounding communities. We used AERMOD to model hourly PCB concentrations, utilizing emission fluxes from a prior study and hourly meteorology provided by the State of Indiana. We also assessed dispersion using hourly observed meteorology from a local airport and high resolution profiles simulated by the Weather Research and Forecasting model...
December 1, 2015: Atmospheric Environment
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