Publications by authors named "Halliday H"

Article Synopsis
  • Wildfires are a growing contributor to air pollution, particularly due to reactive organic compounds (ROC), which have varying health impacts based on their toxicity and abundance.
  • A study combining field campaign data and air quality modeling found that current emissions estimates capture only 40-45% of the total ROC released from wildfires.
  • The research indicates that particulate ROC could significantly affect health risks from smoke exposure, highlighting the need for more accurate toxicity data on these compounds.
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Wildland fires are a major source of gases and aerosols, and the production, dispersion, and transformation of fire emissions have significant ambient air quality impacts and climate interactions. The increase in wildfire area burned and severity across the United States and Canada in recent decades has led to increased interest in expanding the use of prescribed fires as a forest management tool. While the primary goal of prescribed fire use is to limit the loss of life and property and ecosystem damage by constraining the growth and severity of future wildfires, a potential additional benefit of prescribed fire - reduction in the adverse impacts of smoke production and greenhouse gas (GHG) emissions - has recently gained the interest of land management agencies and policy makers in the United States and other nations.

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During thermal processes utilized in affixing fluoropolymer coatings dispersion to fibers and fabrics, coating components are vaporized. It is suspected that per- and polyfluoroalkyl substances (PFAS) from the dispersions may undergo chemical transformations at the temperatures used, leading to additional emitted PFAS thermal byproducts. It is important to characterize these emissions to support evaluation of the resulting environmental and health impacts.

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Article Synopsis
  • The sixth version of the "European Guidelines for the Management of Respiratory Distress Syndrome (RDS)" has been developed by experienced neonatologists and an expert obstetrician, incorporating research up to late 2022.
  • The guidelines emphasize strategies for optimizing outcomes for preterm infants with RDS, including early non-invasive respiratory support, effective use of surfactants, and careful management of oxygen and ventilation.
  • Updated recommendations are based on the latest evidence and include a dedication to Professor Henry Halliday, reflecting the document's endorsement by key European pediatric and neonatal societies.
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During wildfire smoke events public health agencies release advisories to stay indoors, close doors and windows, and operate a portable air cleaner (PAC). The do-it-yourself (DIY) air cleaner consisting of a box fan and a furnace filter is a widely used low-cost alternative to commercial PACs because of its increased accessibility. In this study, we evaluate the clean air delivery rate (CADR) of different DIY air cleaner designs for reducing simulated wildfire smoke and identify operating parameters that may impact their performance and use.

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Accurate fire emissions inventories are crucial to predict the impacts of wildland fires on air quality and atmospheric composition. Two traditional approaches are widely used to calculate fire emissions: a satellite-based top-down approach and a fuels-based bottom-up approach. However, these methods often considerably disagree on the amount of particulate mass emitted from fires.

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Carbonaceous emissions from wildfires are a dynamic mixture of gases and particles that have important impacts on air quality and climate. Emissions that feed atmospheric models are estimated using burned area and fire radiative power (FRP) methods that rely on satellite products. These approaches show wide variability and have large uncertainties, and their accuracy is challenging to evaluate due to limited aircraft and ground measurements.

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Wildfires are a substantial but poorly quantified source of tropospheric ozone (O). Here, to investigate the highly variable O chemistry in wildfire plumes, we exploit the in situ chemical characterization of western wildfires during the FIREX-AQ flight campaign and show that O production can be predicted as a function of experimentally constrained OH exposure, volatile organic compound (VOC) reactivity, and the fate of peroxy radicals. The O chemistry exhibits rapid transition in chemical regimes.

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Article Synopsis
  • The Gaussian observational model for edge to center heterogeneity (GOMECH) is introduced as a new method for analyzing the horizontal chemical structure of smoke plumes.
  • GOMECH uses data from short-lived emissions and long-lived tracers like CO to quantify plume width and center, validated by studying OH and NO oxidation processes in smoke from the FIREX-AQ study.
  • Findings highlight that nitrous acid (HONO) and phenolic emissions are narrower than CO, indicating more losses at the plume edges, while NO production is concentrated at the plume center, with a significant connection between nitrocatechol aerosol and NO production confirmed by large eddy simulations.
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Background: Many infants born preterm develop bronchopulmonary dysplasia (BPD), with lung inflammation playing a role. Corticosteroids have powerful anti-inflammatory effects and have been used to treat individuals with established BPD. However, it is unclear whether any beneficial effects outweigh the adverse effects of these drugs.

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Background: Bronchopulmonary dysplasia (BPD) remains a major problem for infants born extremely preterm. Persistent inflammation in the lungs is important in its pathogenesis. Systemic corticosteroids have been used to prevent or treat BPD because of their potent anti-inflammatory effects.

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The ACT-America project is a NASA Earth Venture Suborbital-2 mission designed to study the transport and fluxes of greenhouse gases. The open and freely available ACT-America data sets provide airborne in situ measurements of atmospheric carbon dioxide, methane, trace gases, aerosols, clouds, and meteorological properties, airborne remote sensing measurements of aerosol backscatter, atmospheric boundary layer height and columnar content of atmospheric carbon dioxide, tower-based measurements, and modeled atmospheric mole fractions and regional carbon fluxes of greenhouse gases over the Central and Eastern United States. We conducted 121 research flights during five campaigns in four seasons during 2016-2019 over three regions of the US (Mid-Atlantic, Midwest and South) using two NASA research aircraft (B-200 and C-130).

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In recent years wildland fires in the United States have had significant impacts on local and regional air quality and negative human health outcomes. Although the primary health concerns from wildland fires come from fine particulate matter (PM), large increases in ozone (O) have been observed downwind of wildland fire plumes (DeBell et al., 2004; Bytnerowicz et al.

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Background: Assessing the quality of clinical research is a key evidence-based practice skill. Clinicians, guideline producers, policy makers, service commissioners, and families need to have a sense of the validity, applicability, and certainty of research evidence when determining how it should inform their decision-making and practice.

Methods: We consider the various methodological and study design factors that contribute to the validity and applicability of clinical research findings.

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Article Synopsis
  • The Korea - United States Air Quality Study (2016) investigated the sources of high ozone and aerosol levels in South Korea through aircraft and ground measurements focused on particulate matter (PM) smaller than 2.5 micrometers.
  • The study analyzed PM data to understand conditions leading to air quality standard violations, especially in the Seoul area, and examined the interaction between meteorological factors and aerosol concentrations.
  • It identified two key meteorological periods influencing PM levels: stagnant clear conditions, which boosted local aerosol production, and cloudy, humid conditions that accelerated aerosol production from both local and transported emissions, suggesting the need for more continuous monitoring to better understand these dynamics.
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As management of respiratory distress syndrome (RDS) advances, clinicians must continually revise their current practice. We report the fourth update of "European Guidelines for the Management of RDS" by a European panel of experienced neonatologists and an expert perinatal obstetrician based on available literature up to the end of 2018. Optimising outcome for babies with RDS includes prediction of risk of preterm delivery, need for appropriate maternal transfer to a perinatal centre and timely use of antenatal steroids.

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