US Environmental Protection Agency Research Articles

Natural resource wealth in sub-Saharan Africa: A boon for public investment in renewable energy?

This paper examines the role of natural resource wealth in financing public investment in renewable energy in 25 sub-Saharan African countries over the period 1996 to 2019. Results from two step system Generalized Method of Moments (GMM) estimates reveal that natural resource wealth negatively affects public investment in renewable energy. A distinction between the types of natural resources allowed to establish that this negative effect comes exclusively from the rents of point natural resources. Furthermore, the results show that institutional quality and human capital favor public investment in renewable energy. These results are robust when using the Driscoll-Kraay estimator. In terms of policy implications, it is imperative to promote good governance of natural resource rents, especially those from point source resources. It will also be necessary to redirect these rents towards the financing of structuring projects such as renewable energies in order to promote sustainable development.

Safe Drinking Water Act Enforcement: Updates and Information for Water Utilities

Key TakeawaysPublic water systems should assess their compliance with regulatory requirements and be prepared for additional scrutiny from regulators.The US Environmental Protection Agency may apply pressure to include climate‐related assessments in Section 1433 risk and resilience plans.Regulators have the authority to seek information from utilities and inspect facilities.Utilities operating in overburdened communities should be especially aware of regulatory requirements and be prepared for more inspections.

The influence of socioeconomic and spatial variables on total maximum daily load progress in the United States

Abstract The total maximum daily load (TMDL) program requires each state in the United States to assess their water bodies, list those that are impaired, and develop TMDL plans or programs to restore them. However, the impact that spatial and socioeconomic variables have on TMDL progress is unknown. This study seeks to fill this gap through a nation-wide analysis of the influence of spatial and socioeconomic variables on indicators of TMDL progress. To do so, data were collected and analyzed for each state, including indicators of TMDL progress, spatial variables, and socioeconomic data. Then, these data were applied to identify overall trends and to define the relationships between indicators of TMDL progress and spatial and socioeconomic variables. Results indicate that the size of a state, the length of total streams, and median household income are related to the percentage of streams that are assessed within a state. In addition, states largely followed similar patterns in TMDL progress based on the US Environmental Protection Agency region that they were within, indicating that location plays a large role. Overall, this study helps to contextualize progress in TMDL development and aid in our understanding of factors that influence the implementation of water quality programs.

A Comparative Study of Heavy Metal Pollution in Ambient Air and the Health Risks Assessment in Industrial, Urban and Semi-Urban Areas of West Bengal, India: An Evaluation of Carcinogenic, Non-Carcinogenic, and Additional Lifetime Cancer Cases

Air pollution is an immense problem due to its detrimental health effects on human populations. This study investigates the distribution of particle-bound heavy metals and associated health risks in three diverse areas (Durgapur as an industrial complex, Kolkata as an urban area, and Bolpur as a semi-urban region) in West Bengal, India. Twenty-one (84 samples) sampling sites were chosen, covering industrial, traffic, residential, and sensitive zones. The respirable suspended particulate matter (RSPM) samples were collected using a portable Mini-Vol Tactical Air Sampler, and heavy metal concentrations (Cd, Cr, Mn, Ni, Pb, and As) were analyzed using ICP-OES. The non-carcinogenic and carcinogenic health risks were assessed using exposure concentration (EC), hazard quotient (HQ), hazard index (HI), and additional lifetime cancer cases. The results highlight variations in heavy metal concentrations across the regions, with industrial areas exhibiting higher levels. Principal component analysis (PCA) unveiled distinct metal co-variation patterns, reflecting sources such as industrial emissions, traffic, and natural contributors. The sum of non-carcinogenic risks (HI) of all heavy metals exceeded the US EPA’s risk limit (HI<1) in both Kolkata and Durgapur, except for Bolpur. Similarly, the sum of cancer risk in three distinct areas exceeded the USEPA limits (1.00E-06). The Monte Carlo simulation revealed the 5th and 95th percentile range of cancer risk was 9.12E-06 to 1.12E-05 in Bolpur, 3.72E-05 to 4.49E-05 in Durgapur and 2.13E-05 to 2.57E-05 in Kolkata. Kolkata had the highest additional lifetime cancer cases compared to Bolpur and Durgapur. This study provides information on the complex connections between heavy metal pollution and possible health risks in industrial, urban, and semi-urban regions.

Epoxy resin for solidification/stabilization of soil contaminated with copper (II): Leaching, mechanical, and microstructural characterization

Among different types of heavy metal-contaminated soil, copper (Cu)-contaminated soil is very serious, and the Cu concentration in it is usually very high. It is common to solidify/stabilize Cu-contaminated soil using alkaline cementitious material. However, the remediated Cu-contaminated soil fails to meet the requirements of environmental safety and load-bearing capacity. This dilemma in the remediation of Cu-contaminated soil hinders the effective utilization of land resources. In this study, epoxy resin (EP) was utilized to solidify/stabilize Cu-contaminated soil due to its stable and rapid curing performance and excellent resistance to acid, alkali, and salt erosion. The mechanical properties, environmental effects, and curing mechanism of EP-cured Cu-contaminated soil were investigated. The results showed that the application of EP significantly enhanced the unconfined compressive strength (UCS), cohesion and internal friction angle of Cu-contaminated soil. All specimens met the UCS criterion specified by the United States Environmental Protection Agency (USPEA), namely no less than 0.35 MPa, which indicated that those EP-cured Cu-contaminated soil were qualified for practical engineering applications. According to the toxicity characteristic leaching procedure (TCLP), the application of EP enhanced the stability of Cu in Cu-contaminated soil. The leaching index of Cu ranged from 11 to 14. A high leaching index showed that the S/S treatment was safe and effective and the remediated Cu-contaminated soil satisfied the environmental requirement for heavy metals. This study confirmed the feasibility of utilizing EP in the solidification/stabilization (S/S) technology to convert high-concentration Cu-contaminated soil into secure and stable engineering materials. The remediation of Cu-contaminated soil by EP lays a solid foundation for the safe treatment and reuse of heavy metal-contaminated land resources.

Bush Kinders: Building Young Children’s Relationships with the Environment

AbstractEarly childhood is an important time for building children’s affinity with nature and the environment. Early childhood professionals play a crucial role in developing young children’s understanding of the natural world. Over the past 50 years, there has been a movement in early childhood education and care contexts to provide young children with the opportunity to learn in natural surroundings such as forest schools and nature kindergartens. This research, occurred in four bush kinders, an Australian example of nature-based, early years education influenced by the forest school approach to education. In this paper we interrogate key ideas concerning environmental education, drawing on seminal empirical research, guiding curriculum documents such as Australia’s Early Years Learning Framework and government policy documents to build understandings of how children’s play can be observed by educators who can then support the children to develop their understandings of the natural world around them. Through ethnography, a methodology that uses both participation and observation of research participants, it became apparent that young children’s play-based learning offers opportunities for development of understandings of the environment. Applying a recent definition of environmental education from the US Environmental Protection Authority (2022), we analysed four vignettes which provide examples of educators and children’s interactions supporting children to build an affinity with nature observed during the research. This research’s implications are novel when considering the relatively new bush kinder approach to early childhood education as the findings remind us of the benefits of bush kinders in generating opportunities for young children’s environmental education.

Heavy metal(loid)s contamination and ecotoxicological hazards in coal, dust, and soil adjacent to coal mining operations, Northwest Pakistan

Heavy metal(loid)s (HM) are ascertained hazardous to the environment due to their toxic, bioaccumulative, and persistent nature. Coal, dust, and surrounding soil near coal mines (n = 21) in each specimen were examined for HM in the districts of Hangu and Kurram. Samples were investigated for HM using the atomic absorption spectrophotometer. Iron (Fe) exhibited the highest mean concentrations, whilst molybdenum (Mo) showed the lowest in the selected coal, dust, and soil specimens were 62,100 and 1.14, 52,610 and 0.9, and 45,300 and 2.0 mg/kg, respectively. HM in studied media was evaluated for ecotoxicological factors, namely contamination factor (CF), potential-ecological risk index (PERI), hazard index (HI), and cancer risk. CF values of dust were very-high and considerable due cadmium (Cd) in the districts of Hangu and Kurram, while that of soil were considerable in both districts. The ecological-risks (190 < PERI<380) were “considerable” due to dust and soil of the Hangu district, while the “moderate” ecological-risk (95 < PERI<190) was noted for the Kurram district. The HI values surpassed the limit of 1 for children due to soil and dust exposures. Higher HI values may pose chronic health risks to the locals. Among exposure routes, oral ingestion was noted as the primary pathway's. CR values were noted as less than the threshold set by the US EPA. This study recommended that HM contaminations be monitored periodically on a priority basis to develop strategies for combating the problem of health concerns.

Prediction of acute fish toxicity (AFT) and fish embryo toxicity (FET) tests by cytotoxicity assays using liver and embryo zebrafish cell lines (ZFL and ZEM2S)

Fish cell-based assays represent potential alternative methods to vertebrates' use in ecotoxicology. In this study, we evaluated the cytotoxicity of thirteen chemicals, chosen from OECD guidelines 236 and 249, in two zebrafish cell lines (ZEM2S and ZFL). We aimed to investigate whether the IC50 values obtained by viability assays (alamar blue, MTT, CFDA-AM, and neutral red) can predict the LC50 values of Acute Fish Toxicity (AFT) test and Fish Embryo Toxicity (FET) test. There was no significant difference between the values obtained by the different viability assays. ZFL strongly correlated with AFT and FET tests (R2AFT = 0.73–0.90; R2FET48h = 0.79–0.90; R2FET96h = 0.76–0.87), while ZEM2S correlated better with the FET test (48h) (R2 = 0.70–0.86) and weakly with AFT and FET tests (96h) (R2AFT = 0.68–0.74 and R2FET96h = 0.62–0.64). The predicted LC50 values allowed the correct categorization of the chemicals in 76.9% (AFT test) – 90.9% (FET test) using ZFL and in 30.7% (AFT test) – 63.6% (FET test) using ZEM2S considering the US EPA criterion for classifying acute aquatic toxicity. ZFL is a promising cell line to be used in alternative methods to adult fish and fish embryos in ecotoxicity assessments, and the method performed in 96-well plates is advantageous in promoting high-throughput cytotoxicity assessment.

Ingestion exposure of public to natural radionuclides and committed effective dose and cancer risk through tuber crops cultivated in Ebonyi State, Nigeria.

Internal exposure of public to radiation arising from ingestion of natural radionuclides in tuber crops of Ebonyi State origin was investigated in this study. Committed effective doses and lifetime cancer risk of 40K, 226Ra, and 232Th in cassava, cocoyam, water yam, and white yam were calculated. The average activity concentrations of 40K, 226Ra, and 232Th determined by gamma spectrometric Na (TI) detector were, respectively, 199.15 ± 23.51, 77.57 ± 7.98, and 118.20 ± 10.72 Bq/kg in cassava; 146.62 ± 40.69, 43.42 ± 7.63, and 75.61 ± 2.89 Bq/kg in cocoyam; 162.81 ± 20.43, 63.17 ± 11.36, and 81.50 ± 10.27 Bq/kg in water yam; and 184.50 ± 20.22, 80.23 ± 10.93, and 116.29 ± 5.93 Bq/kg in white yam. The total committed effective dose via ingestion aligned in this orderof cassava (7.05 mSv/year) > white yam (4.38 mSv/year) > water yam (0.42 mSv/year) > cocoyam (0.21 mSv/year) with overall average dose of 3.12 mSv/year. The values of dose were higher than world average of 0.29 mSv/year given by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The lifetime cancer risk values were above tolerance level of >10-4 prescribed by United States Environmental Protection Agency (USEPA), suggesting probable evolvement of radiogenic cancer morbidity. The data presented in this study contributes to baseline information on radiological characteristics of tuber crops in Ebonyi, which would be valuable to WHO/FAO food safety policy in Nigeria and rest of the world.

Zooplankton-phytoplankton biomass and diversity relationships in the Great Lakes.

Quantifying the relationship between phytoplankton and zooplankton may offer insight into zooplankton sensitivity to shifting phytoplankton assemblages and the potential impacts of producer-consumer decoupling on the rest of the food web. We analyzed 18 years (2001-2018) of paired phytoplankton and zooplankton samples collected as part of the United States Environmental Protection Agency (U.S. EPA) Great Lakes Biology Monitoring Program to examine both the long-term and seasonal relationships between zooplankton and phytoplankton across all five Laurentian Great Lakes. We also analyzed effects of phytoplankton diversity on zooplankton biomass, diversity, and predator-prey (zooplanktivore/grazer) ratios. Across the Great Lakes, there was a weak positive correlation between total algal biovolume and zooplankton biomass in both spring and summer. The relationship was weaker and not consistently positive within individual lakes. These trends were consistent over time, providing no evidence of increasing decoupling over the study period. Zooplankton biomass was weakly negatively correlated with algal diversity across lakes, whereas zooplankton diversity was unaffected. These relationships did not change when we considered only the edible phytoplankton fraction, possibly due to the high correlation between total and edible phytoplankton biovolume in most of these lakes. Lack of strong coupling between these producer and consumer assemblages may be related to lagging responses by the consumers, top-down effects from higher-level consumers, or other confounding factors. These results underscore the difficulty in predicting higher trophic level responses, including zooplankton, from changes in phytoplankton assemblages.

Indoor PM2.5 concentrations in various retail stores in an urban city: Levels, sources and health risk assessment

This study provides information about PM2.5 indoor–outdoor mass concentrations, indoor/outdoor ratios (I/O) and health risks associated with PM2.5 inhalation in seven various retail stores: photocopy centre, bakery, restaurant, hairdresser, dry cleaner, grocery store and hotel. Simultaneous indoor and outdoor measurements were performed in all retail stores in both summer and winter seasons, weekdays and weekends, and also during busy and less-active hours to obtain a realistic exposure assessment. According to the results, indoor PM2.5 levels in the winter season were comparatively higher than those measured in the summer season. The highest PM2.5 concentrations were measured at the hairdresser (3076.0 ± 1345.5 µg/m3) and restaurant (2138.1 ± 636.4 µg/m3) in each sampling period in winter. I/O ratios of &gt;1 were obtained at the hairdresser (7.3–72.3) and restaurant (1.6–17.3) in the winter season and at the hairdresser (1.3–12.7) and dry cleaner (1.1–1.7) in the summer season in all measurement periods. Quite high indoor PM2.5 concentrations and consequently high I/O ratios indicated a strong contribution from indoor sources rather than infiltration of ambient air. Non-carcinogenic health risks due to PM2.5 exposure were evaluated by estimating hazard quotient (HQ) values, and all HQ values were above the acceptable limit of 1 defined by US EPA for the photocopy centre, hairdresser and dry cleaner in both seasons. The results showed that indoor activities at the retail stores were significant for indoor PM2.5 levels as well as occupational health risks faced by employees at retail stores.

BTEX in indoor air of barbershops and beauty salons: Characterization, source apportionment and health risk assessment

BackgroundVolatile organic compounds, mainly BTEX, are among the pollutants of concern in beauty salons and barbershops that threaten both staff personnel and clients' health. This study aimed to determine the concentration of BTEX in barbershops and beauty salons and assess the carcinogenic and non-carcinogenic risks based on the actual risk coefficients. Also, possible sources of BTEX were determined. MethodSamples were collected by passive sampling. Quantitative and qualitative measurements of BTEX compounds were performed using gas chromatography-mass spectrometry (GC-MASS). Subsequently, the health risks were assessed according to the US Environmental Protection Agency. SPSS24 software and positive matrix factorization (PMF) analysis were used for statistical analysis and source apportionment respectively. ResultsToluene is the most abundant compound in beauty salons, with a maximum concentration of 219.4 (μg/m3) in beauty salons. Results indicated that the mean ELCR value estimated for benzene regarding female staff exposure (1.04 × 10−5) was higher than that for men (4.05 × 10−6). Also, ELCR values of ethylbenzene for staff exposure were 2.08 × 10−6 and 3.8 × 10−6 for men and women, respectively, and possess possible carcinogenesis risks. ConclusionUse of solvents and cosmetic products, improper heating systems, and type of service are the sources that probably contribute to BTEX emissions in beauty salons. It is necessary to follow health guidelines and conduct continuous monitoring for their implementation, in addition to setting a mandated occupational regulation framework or air quality requirements, to improve the health conditions in beauty salons.

Ultrasound-assisted extraction followed by liquid chromatography coupled to tandem mass spectrometry for the simultaneous determination of multiclass herbicides in soil.

An analytical methodology based on ultrasound-assisted extraction (UAE) followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) has been developed for the identification and quantification of 9 authorized herbicides in soil (dimethenamid-P, imazamox, S-metolachlor, nicosulfuron, pendimethalin, prosulfuron, bentazone, terbuthylazine, and mesotrione). Preliminary experiments dealing with solvent extraction, theextraction technique, and herbicide response comparison in soil, with and without organic amendments, were carried out with the purpose of obtaining high sample throughput and sensitivity. UAE and thesolvent mixture water:methanol demonstrated higher efficiency and they were selected as sample treatment and extraction solvent, respectively. Critical parameters affecting UAE were optimized by experimental design. In the present research, the extraction technique used in the official EPA microwave-assisted extraction (MAE) methodology (United States Environmental Protection Agency) and UAE optimized methodology were compared. The results indicated that the developed method showed better efficacy since microwave extraction gave very poor responses for nicosulfuron and prosulfuron. The temperature extraction was also optimized; room temperature wasthe most suitable to work with. Under the optimized conditions, the proposed UAE-LC-MS/MS method was assessed in terms of linearity (R2 ≥ 0.9912), accuracy (recoveries around 100%), and precision (relative standard deviation, RSD < 13%). The absence of significant matrix effects allowed quantification in real samples by external calibration with standards prepared in water:methanol. Method sustainability was also evaluated using the metric tool AGREEPrep. Finally, the analysis of real contaminated samples revealed the presence of 7 out of the 9 studied herbicides with S-metolachlor at high concentrations in all samples.

Exploratory Data Analysis of the Groundwater Contaminants at the Former Panna Maria Uranium Recovery Facility.

The former Panna Maria mill was a uranium recovery facility that operated from 1979 to December 1992. Sulfuric acid leach was used to process several tons of ore daily. Therefore, the groundwater was sampled at the site to monitor the concentration of background chemical pollutants. The purpose of this study was to perform exploratory data analysis to evaluate whether the arsenic, nickel, selenium, sulfate, and uranium concentrations were in accord with state-regulated groundwater drinking standards at the site. To accomplish this, a substitution method was used to replace concentration values that were below measurable ranges of well monitoring units. Additionally, random forest regression was employed to account for missing not-at-random values in the dataset. Groundwater samples collected in wells before the facility began operations were used to determine an upper bound on background pollutants consistent with US Environmental Protection Agency Standards. The upper tolerance limit comprising 90% of the groundwater sample at a confidence coefficient of 95% was used to establish alternate concentration limits for each chemical based on well data from the National Uranium Resource Hydrogeochemical and Stream Sediment Reconnaissance program. Results obtained in this analysis establish a baseline on the chemical concentrations in the background groundwater at the former Panna Maria mill.

Polycyclic Aromatic Hydrocarbons (PAHs) in paddy soil around Nam Son landfill area, Ha Noi, Viet Nam

The paddy soils were collected in the rice growing fields and the uncultivated lands around the Nam Son domestic waste landfill in Hanoi. The average concentration of 16 US EPA priority PAHs in dry soil was 61.61 ng/g, with a range of 22.15-115.1 ng/g. The higher levels of PAHs in soil samples were observed in cultivated paddy fields near the landfill in comparison with the fields far from the landfill. On the other hand, there was no difference in PAHs levels in cultivated paddy fields near the landfill and along the irrigation water canal. Concentrations of 16 PAHs in paddy soils decreased in the order: 5 rings &gt; 3 rings &gt; 4 rings &gt; 2 rings &gt; 6 rings in this area. The PAH isomeric diagnostic ratios including Fluth/(Fluth+Pyr) ratio (Ave 0.43, a range of 0.17-0.61), BaA/(BaA+Chr) ratio (Ave 0.51, a range of 0.26-0.63), IcdP/(IcdP+BghiP) ratio (Ave 0.71, a range of 0.51-0.90) indicated that the potential main sources emitted PAHs in paddy soils from pyrogenic biomass combustion and coal burning. Compared with the risk threshold causing adverse impacts on the ecological environment from different countries in the world, concentrations of PAHs in the soil surrounding the Nam Son landfill area were still below the affected limit. However, environmental quality around the landfill area still needs to be regularly monitored to take timely measures to protect the environment in this area.

The rationale behind updates to ambient ozone guidelines and standards.

Although air quality has gradually improved in recent years, as shown by the decrease in PM2.5 concentration, the problem of rising ambient ozone has become increasingly serious. To reduce hazards to human health and environmental welfare exposure to ozone, scientists and government regulators have developed ozone guidelines and standards. These answer the questions of which levels of exposure are hazardous to human health and the environment, and how can ambient ozone exposure be guaranteed, respectively. So what are the basis for the ozone guidelines and standards? This paper reviews in detail the process of revising ozone guidelines and standards by the World Health Organization (WHO) and the United States Environmental Protection Agency (EPA). The present study attempts to explore and analyze the scientific basis and empirical methods for updating guidelines and standards, in a view to guide the future revision process and provide directions for further scientific research. We found many epidemiological and toxicological studies and exposure-response relationships provided strong support for developing and revising the ozone guidelines. When setting standards, ozone exposure has been effectively considered, and the economic costs, health, and indirect economic benefits of standard compliance were reasonably estimated. Accordingly, epidemiological and toxicological studies and the establishment of exposure-response relationships, as well as exposure and risk assessment and benefit-cost estimates of standards compliance should be strengthened for the further update of guidelines and standards. In addition, with the increasing prominence of combined air pollution led by ozone and PM2.5, more joint exposure scientific research related to ozone guidelines and standards should be undertaken.

Environmental persistence, bioaccumulation, and hazards of chemicals in e-cigarette e-liquids: short-listing chemicals for risk assessments

Background/MethodsIncreased use and sales of e-cigarettes raises concerns about the potential environmental impacts throughout their life-cycle. However, few available research studies focus on the environmental impacts and ecotoxicity of e-cigarettes....

Predicting Monthly Community-Level Radon Concentrations with Spatial Random Forest in the Northeastern and Midwestern United States.

In 1987, the United States Environmental Protection Agency recommended installing a mitigation system when the indoor concentration of radon, a well-known carcinogenic radioactive gas, is at or above 148 Bq/m3. In response, tens of millions of short-term radon measurements have been conducted in residential buildings over the past three decades either for disclosure or to initially evaluate the need for mitigation. These measurements, however, are currently underutilized to assess population radon exposure in epidemiological studies. Based on two relatively small radon surveys, Lawrence Berkeley National Laboratory developed a state-of-the-art national radon model. However, this model only provides coarse and invariant radon estimations, which limits the ability of epidemiological studies to accurately investigate the health effects of radon, particularly the effects of acute exposure. This study involved obtaining over 2.8 million historical short-term radon measurements from independent laboratories. With the use of these measurements, an innovative spatial random forest (SRF) model was developed based on geological, architectural, socioeconomical, and meteorological predictors. The model was used to estimate monthly community-level radon concentrations for ZIP Code Tabulation Areas (ZCTAs) in the northeastern and midwestern regions of the United States from 2001 to 2020. Via cross-validation, we found that our ZCTA-level predictions were highly correlated with observations. The prediction errors declined quickly as the number of radon measurements in a ZCTA increased. When ≥15 measurements existed, the mean absolute error was 24.6 Bq/m3, or 26.5% of the observed concentrations (R2 = 0.70). Our study demonstrates the potential of the large amount of historical short-term radon measurements that have been obtained to accurately estimate longitudinal ZCTA-level radon exposures at unprecedented levels of resolutions and accuracy.

Flow-based compact microfluidic electrochemical cell with Parafilm® channels

A planar interdigitated microelectrodes-based microfluidic electrochemical cell (P-μFEC) with channels made by Parafilm® sheets was conceptualized with the application as a sensor for detecting heavy metal ions. Herein, we first-timely proposed a new strategy for creating Parafilm® microchannels using a Plotter cutter and Hot bonding self-sealing method for solid Microfluidic devices (PPHM). For the prepared novel P-µFEC by the PPHM protocol, which operated in the laminar regime, its electrochemical performance was well-studied using the well-known electrochemical reporter potassium Ferri/Ferrocyanide (K3/K4[Fe(CN)6]). A reference electrode (RE) layer deposited at the top silica glass substrate was embedded within the device to minimize the ohmic drop (iRcell) between the working electrode (WE) and RE. The experimental and virtualized computational COMSOL results demonstrated: (i) The changes in the RE's placements had negligible influences on the P-µFEC's electrochemical performance. (ii) The laminar flow's influence on the P-µFEC's electrochemical performance was quite prominent, which was due to the changes in the mass transfer process from diffusion (stationary) to diffusion + convection (hydrodynamic). (iii) A direct virtualized demonstration of laminar flow's influences on the mass transfer process from diffusion (stationary) to diffusion + convection (hydrodynamic) was first timely validated by finite element analysis simulation using COMSOL Multiphysics. (iv) Finally, the proposed P-µFEC showed promise as a sensitive electrochemical sensor for different heavy metal ion substrate (model analytes) detection. The IUPAC detection limits for Cu2+, Pb2+, [Fe(CN)6]3- and Hg2+ is ∼318.6±3.55 μg/L, ∼191±5.4 4 μg/L, ∼113.5±9.9 μg/L, and 8.21±0.88 μg/L, respectively. Among them, the detection limit for Cu2+ and Hg2+ meets the US Environmental Protection Agency (EPA)'s water contamination level for Cu (1300 μg/L) and is close to the EPA level for Hg (2 μg/L), respectively. These findings demonstrate the potential of using the Parafilm® sheet as the microfluidic channel for a flow-based P-μFEC as a novel analytical tool.

Advancing the community health vulnerability index for wildland fire smoke exposure

Wildland fire smoke risks are not uniformly distributed across people and places, and the most vulnerable communities are often disproportionately impacted. This study develops a county level community health vulnerability index (CHVI) for the Contiguous United States (CONUS) using three major vulnerability components: adaptive capacity, sensitivity, and exposure at the national and regional level. We first calculated sensitivity and adaptive capacity sub-indices using nine sensitivity and twenty adaptive capacity variables. These sub-indices were then combined with an exposure sub-index, which is based on the Community Multiscale Air Quality data (2008–2018), to develop CHVI. Finally, we conducted several analyses with the derived indices to: 1) explore associations between the level of fine particulate matter from wildland fires (fire-PM2.5) and the sub-indices/CHVI; 2) measure the impact of fire-PM2.5 on the increase in the annual number of days with 12-35 μg/m3 (moderate) and >35 μg/m3 (at or above unhealthy for sensitive groups) based on the US EPA Air Quality Index categories, and 3) calculate population size in different deciles of the sub-indices/CHVI. This study has three main findings. First, we showed that the counties with higher daily fire-PM2.5 concentration tend to have lower adaptive capacity and higher sensitivity and vulnerability. Relatedly, the counties at high risk tended to experience a greater increase in the annual number of days with 12-35 μg/m3 and >35 μg/m3 than their counterparts. Second, we found that 16.1, 12.0, and 17.6 million people out of 332 million in CONUS reside in the counties in the lowest adaptive capacity decile, highest sensitivity decile, and highest vulnerability decile, respectively. Third, we identified that the US Northwest, California, and Southern regions tended to have higher vulnerability than others. Accurately identifying a community's vulnerability to wildfire smoke can help individuals, researchers, and policymakers better understand, prepare for, and respond to future wildland fire events.