Three-Dimensional Vapor Intrusion Modeling Approach that Combines Wind and Stack Effects on Indoor, Atmospheric, and Subsurface Domains

Vapor intrusion (IV) exposure risks are difficult to characterize due to the role of atmospheric, building and subsurface processes. This study presents a three-dimensional VI model that extends the common subsurface fate and transport equations to incorporate wind and stack effects on indoor air pressure, building air exchange rate (AER) and indoor contaminant concentration to improve VI exposure risk estimates. The model incorporates three modeling programs: (1) COMSOL Multiphysics to model subsurface fate and transport processes, (2) CFD0 to model atmospheric air flow around the building, and (3) CONTAM to model indoor air quality. The combined VI model predicts AER values, zonal indoor air pressures and zonal indoor air contaminant concentrations as a function of wind speed, wind direction and outdoor and indoor temperature. Steady state modeling results for a single-story building with a basement demonstrate that wind speed, wind direction and opening locations in a building play important roles in changing the AER, indoor air pressure, and indoor air contaminant concentration. Calculated indoor air pressures ranged from approximately −10 Pa to +4 Pa depending on weather conditions and building characteristics. AER values, mass entry rates and indoor air concentrations vary depending on weather conditions and building characteristics. The presented modeling approach can be used to investigate the relationship between building features, AER, building pressures, soil gas concentrations, indoor air concentrations and VI exposure risks

US Residential Building Air Exchange Rates: New Perspectives to Improve Decision Making at Vapor Intrusion Sites

Vapor intrusion (VI) is well-known to be difficult to characterize because indoor air (IA) concentrations exhibit considerable temporal and spatial variability in homes throughout impacted communities. To overcome this and other limitations, most VI science has focused on subsurface processes; however there is a need to understand the role of aboveground processes, especially building operation, in the context of VI exposure risks. This tutorial review focuses on building air exchange rates (AERs) and provides a review of literature related building AERs to inform decision making at VI sites. Commonly referenced AER values used by VI regulators and practitioners do not account for the variability in AER values that have been published in indoor air quality studies. The information presented herein highlights that seasonal differences, short-term weather conditions, home age and air conditioning status, which are well known to influence AERs, are also likely to influence IA concentrations at VI sites. Results of a 3D VI model in combination with relevant AER values reveal that IA concentrations can vary more than one order of magnitude due to air conditioning status and one order of magnitude due to house age. Collectively, the data presented strongly support the need to consider AERs when making decisions at VI sites

Air Exchange Rates and Alternatuve Vapor Entry Pathways to Inform Vapor Intrusion Exposure Risk Assessments

Vapor intrusion (VI) is a term used to describe indoor air (IA) contamination that occurs due to the migration of chemical vapors in the soil and groundwater. The overall vapor transport process depends on several factors such as contaminant source characteristics, subsurface conditions, building characteristics, and general site conditions. However, the classic VI conceptual model does not adequately account for the physics of airflow around and inside a building and does not account for chemical emissions from alternative “preferential” pathways (e.g. sewers and other utility connections) into IA spaces. This mini-review provides information about recent research related to building air exchange rates (AERs) and alternative pathways to improve the accuracy of VI exposure risk assessment practices. First, results from a recently published AER study for residential homes across the United States (US) are presented and compared to AERs recommended by the US Environmental Protection Agency (USEPA). The comparison shows considerable differences in AERs when season, location, building age, and other factors are considered. These differences could directly impact VI assessments by influencing IA concentration measurements. Second, a conceptual model for sewer gas entry into buildings is presented and a summary of published field studies is reported. The results of the field studies suggest that alternative pathways for vapors to enter indoor spaces warrant consideration. Ultimately, the information presented in this mini-review can be incorporated into a multiple-lines-of-evidence approach for assessing site-specific VI exposure risks

Occurrence of Chlorinated Volatile Organic Compounds (VOCs) in a Sanitary Sewer System: Implications for Assessing Vapor Intrusion Alternative Pathways

Sewer systems have been recently recognized as potentially important exposure pathways to consider during vapor intrusion assessments; however, this pathway has not been well-characterized and there is need for additional information about the occurrence of volatile organic compounds (VOCs) in sewer systems. This paper reports the results of sewer gas sampling conducted in a sanitary sewer over the years of 2014–2017. Sewer gas samples were collected and analyzed using several different techniques, including TO-15 (grab), TO-17 (passive), Radiello® (passive) and a novel continuous monitoring technique, the Autonomous Rugged Optical Multigas Analyzer (AROMA). The applicability of each of the different approaches used in this study is discussed in the context of investigating sanitary sewers as a vapor intrusion alternative pathway. The data confirmed that trichloroethylene (TCE) concentrations in sewer gas were detected adjacent to and extending hundreds of feet away from a previously defined vapor intrusion area, where TCE was a primary contaminant. TCE concentrations detected in sewer gas ranged from non-detect to 1600 μg/m3. Temporal variability was observed in TCE concentrations over timescales that ranged from minutes to months to years at discrete sampling locations. Spatial variability in sewer gas concentrations was also observed throughout the study area. Temporal and spatial variability may be caused by groundwater contamination sources in the study area, as well as sewer gas transport mechanisms

Appalachian Environmental Health Literacy: Building Knowledge and Skills to Protect Health

Environmental health literacy (EHL) is an emerging, multidisciplinary field that promotes understanding of how environmental exposures can affect human health. After discussing the regional relevance of environmental health knowledge and skills, this article describes three ongoing Appalachian projects that are focused on measuring and building EHL

Exploring approaches to child welfare in contexts of domestic violence and abuse: family group conferences

This article sets out to explore service provision for families affected by domestic violence and abuse. For most families where there are child protection concerns, there are possibilities for intervention from child welfare agencies and domestic abuse services, but these have been criticised as having distinct and disconnected practice cultures and orientation. Recognising this divergence, in this paper, we advocate for safeguarding children affected by domestic violence and abuse using the family group conference (FGC) model. This offers possibilities for a coherent response that integrates both child- and women-centred concerns in a holistic approach to family safety and well-being. Furthermore, it is well documented that safeguarding work involves professionally-led decision-making that is pre-occupied with the management of risk. FGCs, however, promote a partnership approach that engages families in a more democratic decision-making process. As such, FGCs offer families the opportunity to develop their own safety and support plans for the protection and care of children recognising the family's inherent strengths

Prostaglandin insert dinoprostone versus trans-cervical balloon catheter for outpatient labour induction: a randomised controlled trial of feasibility (PROBIT-F)

Background The aim was to assess the feasibility of conducting a randomised controlled trial (RCT) of induction of labour comparing use of two methods in the outpatient setting. Methods An open-label feasibility RCT was conducted in two UK maternity units from October 2017 to March 2019. Women aged ≥ 16 years, undergoing induction of labour (IOL) at term, with intact membranes and deemed suitable for outpatient IOL according to local guidelines were considered eligible. They were randomised to cervical ripening balloon catheter (CRB) or vaginal dinoprostone (Propess). The participants completed a questionnaire and a sub-group underwent detailed interview. Service use and cost data were collected via the Adult Service Use Schedule (AD-SUS). Women who declined to participate were requested to complete a decliners’ questionnaire. Results During the study period, 274 eligible women were identified. Two hundred thirty (83.9%) were approached for participation of whom 84/230 (36.5%) agreed and 146 did not. Of these, 38 were randomised to Propess (n = 20) and CRB (n = 18). Decliner data were collected for 93 women. The reasons for declining were declining IOL (n = 22), preference for inpatient IOL (n = 22) and preference for a specific method, Propess (n = 19). The intended sample size of 120 was not reached due to restrictive criteria for suitability for outpatient IOL, participant preference for Propess and shortage of research staff. The intervention as randomised was received by 29/38 (76%) women. Spontaneous vaginal delivery was observed in 9/20 (45%) women in the dinoprostone group and 11/18 (61%) women in the CRB group. Severe maternal adverse events were recorded in one woman in each group. All babies were born with good condition and all except one (37/38, 97.4%) remained with the mother after delivery. No deaths were recorded. − 21% of women in the dinoprostone group were re-admitted prior to diagnosis of active labour compared to 12% in the CRB group. Conclusions A third of the approached eligible women agreed for randomisation. An RCT is not feasible in the current service context. Modifications to the eligibility criteria for outpatient IOL, better information provision and round the clock availability of research staff would be needed to reach sufficient numbers

One tissue, two fates: different roles of megagametophyte cells during Scots pine embryogenesis

In the Scots pine (Pinus sylvestris L.) seed, embryos grow and develop within the corrosion cavity of the megagametophyte, a maternally derived haploid tissue, which houses the majority of the storage reserves of the seed. In the present study, histochemical methods and quantification of the expression levels of the programmed cell death (PCD) and DNA repair processes related genes (MCA, TAT-D, RAD51, KU80, and LIG) were used to investigate the physiological events occurring in the megagametophyte tissue during embryo development. It was found that the megagametophyte was viable from the early phases of embryo development until the early germination of mature seeds. However, the megagametophyte cells in the narrow embryo surrounding region (ESR) were destroyed by cell death with morphologically necrotic features. Their cell wall, plasma membrane, and nuclear envelope broke down with the release of cell debris and nucleic acids into the corrosion cavity. The occurrence of necrotic-like cell death in gymnosperm embryogenesis provides a favourable model for the study of developmental cell death with necrotic-like morphology and suggests that the mechanism underlying necrotic cell death is evolutionary conserved

Analysis of the interaction with the hepatitis C virus mRNA reveals an alternative mode of RNA recognition by the human La protein

Human La protein is an essential factor in the biology of both coding and non-coding RNAs. In the nucleus, La binds primarily to 3′ oligoU containing RNAs, while in the cytoplasm La interacts with an array of different mRNAs lacking a 3′ UUUOH trailer. An example of the latter is the binding of La to the IRES domain IV of the hepatitis C virus (HCV) RNA, which is associated with viral translation stimulation. By systematic biophysical investigations, we have found that La binds to domain IV using an RNA recognition that is quite distinct from its mode of binding to RNAs with a 3′ UUUOH trailer: although the La motif and first RNA recognition motif (RRM1) are sufficient for high-affinity binding to 3′ oligoU, recognition of HCV domain IV requires the La motif and RRM1 to work in concert with the atypical RRM2 which has not previously been shown to have a significant role in RNA binding. This new mode of binding does not appear sequence specific, but recognizes structural features of the RNA, in particular a double-stranded stem flanked by single-stranded extensions. These findings pave the way for a better understanding of the role of La in viral translation initiation