572 results match your criteria Atmospheric Environment[Journal]


Multipollutant modeling of ozone, reactive nitrogen and HAPs across the continental US with CMAQ-CB6.

Atmos Environ (1994) 2019 Mar;201:62-72

U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC 27711, USA.

The accuracy of atmospheric chemical mechanisms used in air quality models is critical for robustly predicting the production and decay of air pollutants and thus to develop strategies to reduce concentrations that are above levels harmful to humans and ecosystems. In this study we document, evaluate and analyze the implementation of the CB6r3 chemical mechanism used in the Community Multiscale Air Quality (CMAQ) model, including changes that have been to the standard version, and demonstrate the impact of this update on predictions. In general, CB6r3 slightly improves the predictions of ozone and oxides of nitrogen, while providing more consistency with current scientific understanding. Read More

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Data mining approaches to understanding the formation of secondary organic aerosol.

Atmos Environ (1994) 2021 May;252

Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.

This research used data mining approaches to better understand factors affecting the formation of secondary organic aerosol (SOA). Although numerous laboratory and computational studies have been completed on SOA formation, it is still challenging to determine factors that most influence SOA formation. Experimental data were based on previous work described by Offenberg et al. Read More

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The U.S. EPA wildland fire sensor challenge: Performance and evaluation of solver submitted multi-pollutant sensor systems.

Atmos Environ (1994) 2021 ;247

U.S. Forest Service, Rocky Mountain Research Station, Missoula, MT, USA.

Wildland fires can emit substantial amounts of air pollution that may pose a risk to those in proximity (e.g., first responders, nearby residents) as well as downwind populations. Read More

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January 2021

Impact of the COVID-19 induced lockdown measures on concentration in USA.

Atmos Environ (1994) 2021 Jun 7;254:118388. Epub 2021 Apr 7.

Department of Statistics, University of Chicago, United States.

In 2020, most countries around the world have observed varying degrees of public lockdown measures to mitigate the transmission of SARS-CoV-2. As an unintended consequence of reduced transportation and industrial activities, air quality has dramatically improved in many major cities around the world. In this paper, we analyze the environmental impact of the lockdown measures on concentration levels in 48 core-based statistical areas (CBSA) of the United States, during the pre and post-lockdown period of January to June 2020. Read More

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Impact of lockdown during the COVID-19 outbreak on multi-scale air quality.

Atmos Environ (1994) 2021 Jun 2;254:118386. Epub 2021 Apr 2.

Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA.

One of the multi-facet impacts of lockdowns during the unprecedented COVID-19 pandemic was restricted economic and transport activities. This has resulted in the reduction of air pollution concentrations observed globally. This study is aimed at examining the concentration changes in air pollutants (i. Read More

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Improved Estimation of Trends in U.S. Ozone Concentrations Adjusted for Interannual Variability in Meteorological Conditions.

Atmos Environ (1994) 2021 Mar;248

North Carolina State University, Raleigh, NC.

Daily maximum 8-hour average (MDA8) ozone (O) concentrations are well-known to be influenced by local meteorological conditions, which vary across both daily and seasonal temporal scales. Previous studies have adjusted long-term trends in O concentrations for meteorological effects using various statistical and mathematical methods in order to get a better estimate of the long-term changes in O concentrations due to changes in precursor emissions such as nitrogen oxides (NO) and volatile organic compounds (VOCs). In this work, the authors present improvements to the current method used by the United States Environmental Protection Agency (US EPA) to adjust O trends for meteorological influences by making refinements to the input data sources and by allowing the underlying statistical model to vary locally using a variable selection procedure. Read More

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Characteristics of HONO and its impact on O formation in the Seoul Metropolitan Area during the Korea-US Air Quality Study.

Atmos Environ (1994) 2021 ;247

School of Mechanical Engineering, Korea University of Technology and Education, Cheonan, South Korea.

Photolysis of nitrous acid (HONO) is recognized as an early-morning source of OH radicals in the urban air. During the Korea-US air quality (KORUS-AQ) campaign, HONO was measured using quantum cascade - tunable infrared laser differential absorption spectrometer (QC-TILDAS) at Olympic Park in Seoul from 17 May, 2016 to 14 June, 2016. The HONO concentration was in the range of 0. Read More

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January 2021

Deliberating Performance Targets: Follow-on workshop discussing PM, NO, CO, and SO air sensor targets.

Atmos Environ (1994) 2021 ;246

Sacramento Metropolitan Air Quality Management District, Sacramento, CA, USA.

The use of air sensor technology is increasing worldwide for a variety of applications, however, with significant variability in data quality. The United States Environmental Protection Agency held a workshop in July 2019 to deliberate possible performance targets for air sensors measuring particles with aerodynamic diameters of 10 μm or less (PM), nitrogen dioxide (NO), carbon monoxide (CO), and sulfur dioxide (SO). These performance targets were discussed from the perspective of non-regulatory applications and with the sensors operating primarily in a stationary mode in outdoor environments. Read More

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January 2021

Study on the variation of air pollutant concentration and its formation mechanism during the COVID-19 period in Wuhan.

Atmos Environ (1994) 2021 Apr 23;251:118276. Epub 2021 Feb 23.

School of Atmospheric Sciences, Nanjing University, Nanjing, 210023, China.

To prevent the spread of COVID-19 (2019 novel coronavirus), from January 23 to April 8 in 2020, the highest Class 1 Response was ordered in Wuhan, requiring all residents to stay at home unless absolutely necessary. This action was implemented to cut down all unnecessary human activities, including industry, agriculture and transportation. Reducing these activities to a very low level during these hard times meant that some unprecedented naturally occurring measures of controlling emissions were executed. Read More

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Secondary Organic Aerosols from Aromatic Hydrocarbons and their Contribution to Fine Particulate Matter in Atlanta, Georgia.

Atmos Environ (1994) 2020 Feb;223

Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.

Tracers of secondary organic aerosols (SOA) from thirteen aromatic hydrocarbons were quantified in laboratory smog chamber experiments. Class-specific SOA tracers emerged, including 2,3-dihydroxy-4-oxo-pentatonic acid (DHOPA) from monoaromatic volatile organic compounds (VOCs), phthalic acid from naphthalene and 1-methylnaphthalene, and methyl-nitrocatechol isomers from o,m,p-cresol oxidation. Organic carbon mass fractions (f) for these and other tracers were determined and extend the SOA tracer method widely used to apportion biogenic SOC. Read More

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February 2020

Apportioned primary and secondary organic aerosol during pollution events of DISCOVER-AQ Houston.

Atmos Environ (1994) 2021 Jan;244

Department of Environmental Science, Baylor University, Waco, TX, USA.

Understanding the drivers for high ozone (O) and atmospheric particulate matter (PM) concentrations is a pressing issue in urban air quality, as this understanding informs decisions for control and mitigation of these key pollutants. The Houston, TX metropolitan area is an ideal location for studying the intersection between O and atmospheric secondary organic carbon (SOC) production due to the diversity of source types (urban, industrial, and biogenic) and the on- and off-shore cycling of air masses over Galveston Bay, TX. Detailed characterization of filter-based samples collected during Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Houston field experiment in September 2013 were used to investigate sources and composition of organic carbon (OC) and potential relationships between daily maximum 8 h average O and PM. Read More

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January 2021

Relative contributions of selected multigeneration products to chamber SOA formed from photooxidation of a range (C-C) of -alkanes under high NO conditions.

Atmos Environ (1994) 2021 Jan;244(1)

United States Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.

A series of chamber experiments was conducted to investigate the composition of secondary organic aerosol (SOA) following oxidation of a range of parent -alkanes (C-C) in the presence of NO . The relative contribution of selected species representing first, second, and higher generation products to SOA mass was measured using a high-resolution aerosol mass spectrometer. Gas chromatography was also used for a limited set of amenable species. Read More

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January 2021

Modeling lateral plume deflection in the wake of an elongated building.

Atmos Environ (1994) 2020 Aug;234

General Dynamics Information Technology, Research Triangle Park, NC, USA.

The plume dispersion model AERMOD provides an efficient method for modeling ground-level pollutant concentrations in wakes of buildings. In recent years, several studies have shown that the downwash algorithms within AERMOD often perform poorly in certain applications. Some studies have proposed modifications to the downwash algorithm in AERMOD to bring the model closer to representing the underlying physical processes associated with building downwash and closer to more accurately modeling observed pollutant concentrations. Read More

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Global and regional variations in aerosol loading during COVID-19 imposed lockdown.

Authors:
S D Sanap

Atmos Environ (1994) 2021 Feb 8;246:118132. Epub 2020 Dec 8.

Climate Research and Services, India Meteorological Department, Ministry of Earth Sciences, Shivajinagar, Pune, 411005, India.

In the backdrop of upward trend in anthropogenic aerosols over global hotspot regions, the air quality had improved worldwide post declaration of the Corona virus disease-2019 (COVID-19) as a global pandemic in mid-March-2020. Present study using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite derived aerosol optical depth (AOD) and the Modern-Era Retrospective analysis for Research and Applications (MERRA) version-2 datasets however, demonstrates the regional variation in aerosol loading during peak of the lockdown period. Reduction in aerosol loading over majority of the aerosol hotspots is observed from mid-March/April-2020 with highest percentage reduction in the month of May. Read More

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February 2021

Drivers for the poor air quality conditions in North China Plain during the COVID-19 outbreak.

Atmos Environ (1994) 2021 Feb 25;246:118103. Epub 2020 Nov 25.

Fujian Meteorological Institute, Fuzhou, 350001, China.

China's lockdown to control COVID-19 brought significant declines in air pollutant emissions, but haze was still a serious problem in North China Plain (NCP) during late-January to mid-February of 2020. We seek the potential causes for the poor air quality in NCP combining satellite data, ground measurements and model analyses. Efforts to constrain COVID-19 result in a drop-off of primary gaseous pollutants, e. Read More

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February 2021

COVID-19 mitigation measures and nitrogen dioxide - A quasi-experimental study of air quality in Munich, Germany.

Atmos Environ (1994) 2021 Feb 22;246:118089. Epub 2020 Nov 22.

Institute for Medical Information Processing, Biometry, and Epidemiology - IBE, LMU Munich, Germany.

Background: In response to the COVID-19 pandemic, the Bavarian State government announced several COVID-19 mitigation measures beginning on March 16, 2020, which likely led to a reduction in traffic and a subsequent improvement in air quality. In this study, we evaluated the short-term effect of COVID-19 mitigation measures on NO concentrations in Munich, Germany.

Methods: We applied two quasi-experimental approaches, a controlled interrupted time-series (c-ITS) approach and a synthetic control (SC) approach. Read More

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February 2021

Community evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission through air.

Atmos Environ (1994) 2021 Feb 20;246:118083. Epub 2020 Nov 20.

Department of Infectious Disease Control and Prevention, Guangzhou Center for Disease Control and Prevention, Guangzhou, 510440, China.

Background: Nine COVID-19 (Corona Virus Disease, 2019) cases were observed in one community in Guangzhou. All the cases lived in three vertically aligned units of one building sharing the same piping system, which provided one unique opportunity to examine the transmission mode of SARS-CoV-2.

Methods: We interviewed the cases on the history of travelling and close contact with the index patients. Read More

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February 2021

Iron Speciation in Particulate Matter (PM) from Urban Los Angeles Using Spectro-microscopy Methods.

Atmos Environ (1994) 2021 Jan 14;245. Epub 2020 Oct 14.

Sierra Nevada Research Institute and School of Natural Sciences, University of California, Merced, 95343, USA.

The speciation, oxidation states, and relative abundance of iron (Fe) phases in PM samples from two locations in urban Los Angeles were investigated using a combination of bulk and spatially resolved, element-specific spectroscopy and microscopy methods. Synchrotron X-ray absorption spectroscopy (XAS) of bulk samples (i.e. Read More

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January 2021

Contrasting wet deposition composition between three diverse islands and coastal North American sites.

Atmos Environ (1994) 2021 Jan 28;244. Epub 2020 Sep 28.

Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA.

This study examined spatial variations of precipitation accumulation and chemistry for six sites located on the West and East Coasts of the U.S., and one site each on the islands of Hawaii, Bermuda, and Luzon of the Philippines (specifically Manila). Read More

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January 2021

Sources, frequency, and chemical nature of dust events impacting the United States East Coast.

Atmos Environ (1994) 2020 Jun 5;231. Epub 2020 Apr 5.

Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA.

This study examines 14 years (2004-2017) of surface aerosol composition data from the EPA IMPROVE network with a focus on the monthly profile, sources, and chemical nature of extreme dust events (>92nd percentile of fine soil concentration each month) impacting ten sites along the United States East Coast ranging in latitude from Florida to Maine. Based on trajectory, remote sensing, and reanalysis data, dust events were categorized into four source categories: African, Asian, Mix (African + Asian), and Other (anything other than African and Asian). The results reveal that extreme dust events account for between 3. Read More

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Differential inflammatory potential of particulate matter (PM) size fractions from Imperial Valley, CA.

Atmos Environ (1994) 2021 Jan 14;244. Epub 2020 Oct 14.

Center for Health and the Environment, University of California, Davis.

Particulate matter (PM) in Imperial Valley originates from a variety of sources such as agriculture, traffic at the border crossing, emissions from the cross-border city of Mexicali, and the drying lakebed of the Salton Sea. Dust storms in Imperial Valley, California regularly lead to exceedances of the federal air quality standards for PM (diameter less than 10 microns). To determine if there are differences in the composition and biological response to Imperial County PM by size, ambient PM samples were collected from a sampling unit stationed in the northern-most part of the valley, South of the Salton Sea. Read More

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January 2021

Impact of dimethylsulfide chemistry on air quality over the Northern Hemisphere.

Atmos Environ (1994) 2020 Oct;244:117961

Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain.

We implement oceanic dimethylsulfide (DMS) emissions and its atmospheric chemical reactions into the Community Multiscale Air Quality (CMAQv53) model and perform annual simulations without and with DMS chemistry to quantify its impact on tropospheric composition and air quality over the Northern Hemisphere. DMS chemistry enhances both sulfur dioxide (SO) and sulfate ( ) over seawater and coastal areas. It enhances annual mean surface SO concentration by +46 pptv and by +0. Read More

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October 2020

Advancing methodologies for applying machine learning and evaluating spatiotemporal models of fine particulate matter (PM) using satellite data over large regions.

Atmos Environ (1994) 2020 Oct 17;239. Epub 2020 Jul 17.

Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Reconstructing the distribution of fine particulate matter (PM) in space and time, even far from ground monitoring sites, is an important exposure science contribution to epidemiologic analyses of PM health impacts. Flexible statistical methods for prediction have demonstrated the integration of satellite observations with other predictors, yet these algorithms are susceptible to overfitting the spatiotemporal structure of the training datasets. We present a new approach for predicting PM using machine-learning methods and evaluating prediction models for the goal of making predictions where they were not previously available. Read More

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October 2020

Interannual Variation of the East Asia Jet Stream and Its Impact on the Horizontal Distribution of Aerosol in Boreal Spring.

Atmos Environ (1994) 2020 Feb 22;223. Epub 2020 Jan 22.

NASA Goddard Space Flight Center, Greenbelt, Maryland, U.S.A.

Interannual variation of the aerosol optical depth (AOD) in East Asia has been investigated using Moderate Resolution Imaging Spectroradiometer (MODIS) data and Modern Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) data for 2000-2018. The data analysis focuses on boreal spring when Siberian biomass burning is at its seasonal maximum. The results indicate that the significant increase in organic and black carbon is primarily caused by emissions from biomass burning in East Asia, which leads to significant interannual variations in aerosol loading and pan-Pacific transport. Read More

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February 2020

Use of low-cost PM monitors and a multi-wavelength aethalometer to characterize PM in the Yakama Nation Reservation.

Atmos Environ (1994) 2020 Mar 20;224. Epub 2020 Jan 20.

University of Washington Department of Environmental and Occupational Health Sciences, 4225 Roosevelt Way NE, STE 301 Seattle, WA 98105.

Rural lower Yakima Valley, Washington is home to the reservation of the Confederated Tribes and Bands of the Yakama Nation, and is a major agricultural region. Episodic poor air quality impacts this area, reflecting sources of particulate matter with a diameter of less than 2.5 micrometers (PM) that include residential wood smoke, agricultural biomass burning and other emissions, truck traffic, backyard burning, and wildfire smoke. Read More

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Assessing the pollutant evolution mechanisms of heavy pollution episodes in the Yangtze-Huaihe valley: A multiscale perspective.

Atmos Environ (1994) 2021 Jan 8;244:117986. Epub 2020 Oct 8.

Key Laboratory of Atmospheric Chemistry of CMA, Chinese Academy of Meteorological Sciences, Beijing, 100081, China.

The Yangtze-Huaihe (YH) region experiences heavy aerosol pollution, characterized by high PM concentration. To unravel the pollutant evolution mechanism during the heavy pollution episodes (HPEs), this study combined observational data analysis and three-dimensional WRF-Chem simulations. From December 2, 2016 to January 15, 2017, YH region experienced 4 HPEs under the control by synoptic system, normally associated with a transport stage (TS) and a cumulative stage (CS). Read More

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January 2021

Impacts of COVID-19 lockdown, Spring Festival and meteorology on the NO variations in early 2020 over China based on in-situ observations, satellite retrievals and model simulations.

Atmos Environ (1994) 2021 Jan 28;244:117972. Epub 2020 Sep 28.

State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), Beijing, 100029, China.

The lockdown measures due to COVID-19 affected the industry, transportation and other human activities within China in early 2020, and subsequently the emissions of air pollutants. The decrease of atmospheric NO due to the COVID-19 lockdown and other factors were quantitively analyzed based on the surface concentrations by in-situ observations, the tropospheric vertical column densities (VCDs) by different satellite retrievals including OMI and TROPOMI, and the model simulations by GEOS-Chem. The results indicated that due to the COVID-19 lockdown, the surface NO concentrations decreased by 42% ± 8% and 26% ± 9% over China in February and March 2020, respectively. Read More

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January 2021

Evaluation of NASA's high-resolution global composition simulations: Understanding a pollution event in the Chesapeake Bay during the summer 2017 OWLETS campaign.

Atmos Environ (1994) 2020 Feb 16;222. Epub 2019 Nov 16.

Science Systems and Applications Inc. (SSAI), Lanham, MD, 20706, USA.

Recirculation of pollutants due to a bay breeze effect is a key meteorological mechanism impacting air quality near urban coastal areas, but regional and global chemical transport models have historically struggled to capture this phenomenon. We present a case study of a high ozone (O) episode observed over the Chesapeake Bay during the NASA Ozone Water-Land Environmental Transition Study (OWLETS) in summer 2017. OWLETS included a complementary suite of ground-based and airborne observations, with which we characterize the meteorological and chemical context of this event and develop a framework to evaluate model performance. Read More

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February 2020

Urban wind field analysis from the Jack Rabbit II Special Sonic Anemometer Study.

Atmos Environ (1994) 2020 Dec;243:117871

North Carolina State University (NCSU), Marine, Earth, and Atmospheric Sciences Department (MEAS), 2800 Faucette Drive, 1125, Jordan Hall, Raleigh, NC, USA.

The Jack Rabbit II Special Sonic Anemometer Study (JRII-S), a field project designed to examine the flow and turbulence within a systematically arranged mock-urban environment constructed from CONEX shipping containers, is described in detail. The study involved the deployment of 35 sonic anemometers at multiple heights and locations, including a 32 m tall, unobstructed tower located about 115 m outside the building array to document the approach wind flow characteristics. The purpose of this work was to describe the experimental design, analyze the sonic data, and report observed wind flow patterns within the urban canopy in comparison to the approaching boundary layer flow. Read More

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December 2020