Are National Breast and Cervical Cancer Early Detection Program Recipients Providing Services in Counties Heavily Burdened by Breast and Cervical Cancer?

INTRODUCTION: Alignment of National Breast and Cervical Cancer Early Detection Program (NBCCEDP) clinical services with the spatial distribution of breast and cervical cancer burden is essential to maximizing programmatic impact and addressing cancer disparities. This study identified spatial clustering of breast and cervical cancer burden scores and assessed whether and to what extent NBCCEDP clinical services were associated with clusters for the 5-year period, 2015-2019. METHODS: We examined burden scores for spatial clustering using Local Indicators of Spatial Association (LISA) tests in GeoDA. We then used t-tests to compare the NBCCEDP 5-year average percentage of eligible women served clinical breast and cervical cancer services between hotspot (high burden) and coolspot clusters. RESULTS: There was statistically significant spatial clustering in the pattern of breast and cervical cancer burden scores across counties, with hotspot clusters mostly observed in the Southern region, Idaho and Nevada. For both breast and cervical cancer, higher percentages of eligible women received breast and cervical cancer clinical services in coolspot clusters compared to hotspot clusters during each year from 2015-2019. CONCLUSION: NBCCEDP clinical services can help reduce breast and cervical cancer burden. Yet, during 2015-2019, increased service delivery was not aligned with the spatial distribution of counties with greater breast and cervical cancer burdens. NBCCEDP recipients may improve their impact on breast and cervical cancer burden by prioritizing and consistently increasing service delivery in cancer burden hotspot clusters if they have not already maximized their resources in these areas.

Mental Health Conditions- and Substance Use-Associated Emergency Department Visits during the COVID-19 Pandemic in Nevada, USA.

Background-Mental health conditions and substance use are linked. During the COVID-19 pandemic, mental health conditions and substance use increased, while emergency department (ED) visits decreased in the U.S. There is limited information regarding how the pandemic has affected ED visits for patients with mental health conditions and substance use. Objectives-This study examined the changes in ED visits associated with more common and serious mental health conditions (suicidal ideation, suicide attempts, and schizophrenia) and more commonly used substances (opioids, cannabis, alcohol, and cigarettes) in Nevada during the COVID-19 pandemic in 2020 and 2021 compared with the pre-pandemic period. Methods-The Nevada State ED database from 2018 to 2021 was used (n = 4,185,416 ED visits). The 10th Revision of the International Classification of Diseases identified suicidal ideation, suicide attempts, schizophrenia, and the use of opioids, cannabis, alcohol, and cigarette smoking. Seven multivariable logistic regression models were developed for each of the conditions after adjusting for age, gender, race/ethnicity, and payer source. The reference year was set as 2018. Results-During both of the pandemic years (2020 and 2021), particularly in 2020, the odds of ED visits associated with suicidal ideation, suicide attempts, schizophrenia, cigarette smoking, and alcohol use were all significantly higher than those in 2018. Conclusions-Our findings indicate the impact of the pandemic on mental health- and substance use-associated ED visits and provide empirical evidence for policymakers to direct and develop decisive public health initiatives aimed at addressing mental health and substance use-associated health service utilization, especially during the early stages of large-scale public health emergencies, such as the COVID-19 pandemic.

Isolated Vascular Rings Are Common Cardiovascular Malformations.

OBJECTIVE: We investigated the prevalence of isolated vascular rings in the general population of Southern Nevada. METHODS: We identified those prenatally and postnatally diagnosed with an isolated vascular ring between January 2014 and December 2021. We included only those with vascular or ligamentous structures completely encircling the trachea and esophagus. To investigate the prevalence of isolated vascular rings, we included only those with situs solitus, levocardia, and no significant intracardiac malformations. RESULTS: We identified 112 patients. Of the 112, 66 (59%) were female. There were approximately 211,000 total live births in Southern Nevada for the study period, for an overall prevalence of 5.3 isolated vascular rings per 10 000 live births. However, for the years 2014 to 2017, the average prevalence figure was 3.5 per 10 000 live births, and for the years 2018 to 2021, the average prevalence figure was 7.1 (range 6.5-8.0) per 10 000 live births. Simultaneously, the prenatal detection rate rose from 66% to 86%. CONCLUSIONS: Isolated vascular rings are common cardiovascular malformations. As prenatal detection rates in the Southern Nevada general population approach 90%, the prevalence figures for isolated vascular rings appear to asymptote at about 7 per 10 000 live births.

Isolated Balanced Complete Atrioventricular Septal Defects: Prenatal Detection and Outcome in Nevada.

We analyzed patients with isolated, balanced complete atrioventricular septal defects. We identified 71 patients born in Nevada, between January 2008 and December 2020. We also analyzed prenatal detection rates. Of the 71, 61 (85%) had trisomy 21, 1 (1%) had CHARGE syndrome and 22q.11 deletion, and 10 (14%) had no chromosomal abnormalities. Of the 71, 67 had prenatal care, and 43/67 (64%) were prenatally diagnosed. Prenatal detection rate for 2008-2012 was 9/20 (45%) and 18/21 (86%) for 2018-2020, P = .03. Of the 71, 67 underwent surgical repair with 1 current postpulmonary artery banding and 0 surgical deaths. Of the 67, 3 (4%) had heart block. Only 1 (1.5%) patient had reoperation for a mitral valve replacement. Of the 71, 67 (94%) are alive during a 6-year average (range = 0-12 years) follow-up. In conclusion, surgical and long-term outcomes were excellent. Also, high state-wide, general population prenatal detection rates were achieved.

Prenatal diagnosis of hypoplastic aortic arch without intracardiac malformations: The nevada experience.

OBJECTIVE: We reviewed our center's experience with neonatal and infant hypoplastic aortic arch, unassociated with intracardiac malformations, and investigated changes in prenatal detection rates over time for those requiring therapeutic procedures. METHODS: We identified all prenatal diagnoses of hypoplastic aortic arch with situs solitus, unassociated with intracardiac malformations, made in Nevada between May 2017 and April 2022. In addition, we identified all those 0-180 days old, with prenatal care, that underwent a surgical or interventional cardiac catheterization aortic arch procedure, whether prenatally or postnatally diagnosed. We excluded those with ventricular septal defects, functionally univentricular hearts, interrupted aortic arches, or any associated malformation requiring an additional surgical or interventional procedure ≤6 months old. Additionally, we calculated prenatal detection rates for those undergoing a surgical or interventional catheterization procedure for each of the 5 years. RESULTS: We identified 107 patients prenatally and postnatally. Of the 107 patients, 56 (34 prenatally diagnosed and 22 postnatally diagnosed) underwent an aortic arch procedure, and 51 additionally prenatally diagnosed, live-born infants did not undergo a procedure. Of the 56 procedures, 2 were by interventional catheterization, and 54 underwent a surgical repair. Prenatal detection for those undergoing a procedure statistically significantly increased over the 5 years from 38% to 82%, rho = 0.95 (p = .04). CONCLUSIONS: Currently in Nevada, our prenatal detection rate is >80% in the general population for those between 0 and 6 months old who require a therapeutic procedure for aortic arch obstruction without intracardiac malformations.

Complex neonatal congenital heart surgery in Nevada.

OBJECTIVE: We reviewed our center's surgical mortality rates for those who underwent a Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) category 4 or 5 neonatal cardiovascular surgery. METHODS: We identified all patients who underwent a STAT category 4 or 5 neonatal index cardiovascular surgical procedure between July 2015 and July 2021. RESULTS: We identified 239 patients. We divided them into two groups: (1) 42 (17.6%) ≤2.5 kg, and (2) 197 (82.4%) were >2.5 kg at the time of neonatal surgery. Of those ≤2.5 kg, 18/42 (42.9%) had syndromes or associated noncardiac malformations versus 34/197 (17.3%) of those >2.5 kg, p = .0093. Thirty-day discharge mortality for those ≤2.5 kg was 3/42 (7.1%) versus l0/197 (5.1%) for those >2.5 kg, p = .83. CONCLUSIONS: Weight at the time of surgery, presence of syndromes, and associated noncardiac malformations did not affect mortality in those undergoing complex neonatal STAT 4 or 5 category cardiovascular surgery.

Postmortem THC in decedents following legalization of recreational cannabis in Clark County, Nevada.

Marijuana is the most prevalent illicit substance used globally. With increasing US legalizing recreational marijuana, more evidence is vital to minimize potential health risks. This study was conducted to test several hypotheses regarding postmortem THC/COOH-THC in decedents before and after legalization of recreational marijuana in Nevada. We also compared presence of THC/COOH-THC in decedents with respect to manner of death as recorded by the Clark County Office of the Coroner/Medical Examiner. THC/COOH-THC concentrations for years 2015-2016 (pre-legalization) and 2017-2019 (post-legalization) were compared through an independent samples t-test and chi-square tests. A binary logistic regression was used to compare the presence of THC/COOH-THC with covariates: age, gender, race, and manner of death. The average concentration of THC/COOH-THC detected per decedent did not significantly differ before and after recreational legalization, whereas the proportion of decedents testing positive for THC showed a small but significant increase following legalization although no significant change in COOH-THC was detected. The likelihood of testing positive for THC/COOH-THC decreased as age increased. Sex, race, and manner of death were all associated with the relative risk of presence of THC/COOH-THC in toxicology reports. An increase in proportion of users but not in concentration of THC/COOH-THC was observed after legalization. The results are generally consistent with national reports and suggest toxicology data from decedents is a valuable method for surveying marijuana use by the general public. The early adoption of recreational marijuana by neighboring states may have precluded any major changes in use following legalization in Nevada.

Decreasing Mortality for STAT 4 and 5 Neonatal Heart Surgeries Concurrent With Improving Prenatal Detection: The Nevada Experience.

Objective: Our objective was to investigate whether a relationship existed between our center's STAT 4 and 5 category surgical mortality and general-population prenatal detection rates in Nevada. Methods: We identified patients who underwent STAT 4 and 5 neonatal index cardiovascular surgeries at our center between October 2012 and September 2021. Additionally, we calculated prenatal detection rates for each of the 9 retrospective study years. We used descriptive statistics and nonparametric testing, including the Spearman Rho correlation (R) and the Mann-Whitney U-tests, with a significant P-value set at < .05. Results: We identified 356 patients. We noted a statistically significant increasing trend in prenatal detection percentages (rho = 0.79, P = .01), concurrent with a statistically significant decreasing trend in surgical mortality (rho = -0.82, P = .007). Conclusions: Despite encouraging results, we could not establish a cause-and-effect relationship between concurrent decreased surgical mortality and increased prenatal detection rates for patients undergoing STAT 4 and 5 surgical procedures at our center.

The Nevada peripheral artery disease screening effort in a Medicare Advantage population and subsequent mortality and major adverse cardiovascular event risk.

BACKGROUND: Contemporary estimates of undetected asymptomatic lower extremity peripheral artery disease (PAD) in the community and its association with adverse outcomes in the population are lacking. We investigated the long-term association between previously undetected PAD and subsequent all-cause mortality and major adverse cardiovascular events (MACE) for Medicare Advantage beneficiaries aged ≥65 years in a large metropolitan area characterized by concentrations of atherosclerotic risk factors and a more vulnerable socioeconomic risk profile. METHODS: Data were derived from the patients' electronic medical records and linked with claims outcomes data for 13,971 Medicare Advantage beneficiaries aged ≥65 years who had undergone PAD screening in 2016 as a part of their routine annual health assessment in the greater Las Vegas, Nevada, metropolitan area. PAD screening was performed with their primary care provider using volume plethysmography system methods. The association between PAD screening status and 1- and 3-year all-cause mortality and MACE rates was documented. RESULTS: The cohort had a mean age of 75.3 ± 6.6 years, and 57.7% were women. Of the 13,768 patients, 4351 (31.6%) had had a positive PAD screening result. Almost 60% had had a lower socioeconomic income level, with 15.1% living under the poverty level. The risk estimates associated with a positive vs negative PAD screening result for both all-cause mortality and MACE were as follows: unadjusted hazard ratio (HR) for mortality, 2.17 (95% confidence interval [CI], 1.79-2.63) and unadjusted HR for MACE, 2.00 (95% CI, 1.15-3.49) at 1 year and unadjusted HR for mortality, 2.04 (95% CI, 1.84-2.26) and unadjusted HR for MACE, 1.67 (95% CI, 1.37-2.02) at 3 years. After multivariable adjustment, all associations persisted (P < .001), with HRs ranging from 1.41 to 1.69, except for that for 1-year MACE (similar risk estimate but P = .09). CONCLUSIONS: A positive screening result for previously undetected lower extremity PAD was independently associated with short- and long-term increased risks of mortality and MACE for individuals aged ≥65 years living in a large, metropolitan area.

Distribution and source of plutonium in sediments from the southern Gulf of Mexico.

Here, we report on new data (75 analyses) of plutonium (Pu) isotopes to elucidate activity concentrations, inventories, sources, and their transport from the ocean surface to the seafloor from a collection of six deep-sea sediment cores (depths ranging from 257 to 3739 m) in the southern Gulf of Mexico. Sediment cores collected from the continental shelf and upper slope region of the Gulf of Mexico showed 240Pu/239Pu ratios of 0.15 to 0.26, and 239+240Pu-inventories ranging from 14.7 to 33.0 Bq m-2. Inventories and ratios are consistent with global fallout Pu for this tropical region. In contrast, sediment cores collected from the lower slope region and abyssal plain showed low 240Pu/239Pu ratios of 0.07 to 0.13 and much lower 239+240Pu inventories below 6.8 Bq m-2. This implies that only a small fraction of the expected global fallout Pu has reached the deep-sea sediments. The low 240Pu/239Pu isotope ratios indicate that fallout from the Nevada testing site was an important source of Pu in deep-sea sediments, and that this Pu was likely more efficiently scavenged from the water column than Pu from global fallout. We estimated that up to 44% of the total inventory of 239+240Pu in deep-sea sediments is due to the Nevada source. Low values and a progressive decrease of 240Pu/239Pu ratios and 239+240Pu inventories with increasing water depth have been previously reported for the Gulf of Mexico. Analysis of Pu isotopes in two sediment traps from the upper slope regions shows 240Pu/239Pu ratios comparable to those observed in global fallout. These results indicate that global fallout Pu is currently the main source of Pu in sinking particles in the water column. Therefore, a significant fraction of global fallout Pu must still be present, either in a dissolved phase, or as biologically recycled material in the water column, or scavenged on the shelf and shelf break. Our results bring to light important questions on the application of Pu isotopes to establish sediment chronologies in deep-sea sediments, since global fallout features such as the 1963 maximum are not available.

Protozoa reduction through secondary wastewater treatment in two water reclamation facilities.

The State of Nevada, USA Administrative Code requires a 12-log enteric virus reduction/inactivation, 10-log Giardia cyst reduction, and 10-log Cryptosporidium oocyst reduction for Category A+ reclaimed water suitable for indirect potable reuse (IPR) based on raw wastewater to potable reuse water. Accurately demonstrating log10 reduction values (LRVs) through secondary biological treatment prior to an advanced water treatment train enables redundancy and resiliency for IPR projects while maintaining a high level of public confidence. LRVs for Cryptosporidium and Giardia resulting from secondary biological treatment are not fully established due to a wide range of performance variabilities resulting from different types of secondary biological treatment processes employed in water reclamation. A one-year investigation of two full-scale northern Nevada (e.g. ≤4 mgd; 1.5 × 107 L/day) water reclamation facilities (WRFs) was conducted to monitor Cryptosporidium oocysts and Giardia cysts in untreated wastewater and secondary effluent. This study aimed at establishing secondary treatment LRVs, monitor WRF performance and attempted to correlate performance to protozoan reduction. California's IPR regulations, in which Nevada IPR regulations were modeled after, were based on a maximum concentration of 5-logs (cysts/L) of Giardia and 4-logs (oocysts/L) of Cryptosporidium. The recovery-corrected Giardia and Cryptosporidium concentrations measured in untreated influent (20 samples each at each WRF) were below 5-log cysts/L at the 99th percentile (maximum 4.4-log cysts/L) and 4-log oocysts/L (maximum 2.7 log oocysts/L), respectively. Both secondary treatment WRFs produced secondary effluent that is consistently better than federal and the State of Nevada requirements and perform within an operating envelop for other secondary facilities. Given the results, it appears that a minimum conservative estimate for LRVs for well-operated secondary activated sludge treatment plants (at the 5th percentile) of 0.5 LRV credit for Cryptosporidium and 2.0 LRV for Giardia is warranted. These minimum LRVs are consistent with a conservative review of the available literature.

Prenatal diagnosis in Nevada for patients undergoing cardiovascular surgery in the first six months.

OBJECTIVE: We reviewed our center's experience with prenatal detection in Nevada's general population for young infants undergoing cardiovascular surgery. METHODS: We identified patients born in Nevada that underwent an initial cardiovascular surgery between 0 and 6 months old with birth dates between August 2012 and July 2021. Additionally, we calculated prenatal congenital cardiovascular malformation detection rates for each of the 9 years. RESULTS: We identified 660 patients. For the 660 patients, 649 (98%) mothers underwent prenatal care, which included at least one anatomical-survey obstetric ultrasound. Of the 649 with prenatal care, 395 (61%) had a prenatal diagnosis overall. However, prenatal diagnosis improved over the 9 years from 44% in 2012 to 79% in 2021 (correlation coefficient of 0.93, p = .00024). CONCLUSIONS: Our results demonstrated a progressive rise in prenatal detection rates for young infants undergoing cardiovascular surgery in Nevada.

Surveillance of the Incidence and Mortality of Oral and Pharyngeal, Esophageal, and Lung Cancer in Nevada: Potential Implications of the Nevada Indoor Clean Air Act.

Reviews of national and state-specific cancer registries have revealed differences in rates of oral, esophageal, and lung cancer incidence and mortality that have implications for public health research and policy. Many significant associations between these types of cancers and major risk factors, such as cigarette usage, may be influenced by public health policy such as smoking restrictions and bans-including the Nevada Clean Indoor Air Act (NCIAA) of 2006 (and subsequent modification in 2011). Although evaluation of general and regional advances in public policy have been previously evaluated, no recent studies have focused specifically on the changes to the epidemiology of oral and pharyngeal, esophageal, and lung cancer incidence and mortality in Nevada. Methods: Cancer incidence and mortality rate data were obtained from the National Cancer Institute (NCI) Division of Cancer Control and Population Sciences (DCCPS) Surveillance, Epidemiology and End Results (SEER) program. Most recently available rate changes in cancer incidence and mortality for Nevada included the years 2012-2016 and are age-adjusted to the year 2000 standard US population. This analysis revealed that the overall rates of incidence and mortality from these types of cancer in Nevada differs from that observed in the overall US population. For example, although the incidence rate of oral cancer is decreasing in the US overall (0.9%), it is stable in Nevada (0.0%). However, the incidence and mortality rates from esophageal cancer are also decreasing in the US (-1.1%, -1.2%, respectively), and are declining more rapidly in Nevada (-1.5%, -1.9%, respectively). Similarly, the incidence and mortality rates from lung are cancer are declining in the US (-2.5%, -2.4%, respectively) and are also declining more rapidly in Nevada (-3.2%, -3.1%, respectively). Analysis of previous epidemiologic data from Nevada (1999-2003) revealed the highest annual percent change (APC) in oral cancer incidence in the US was observed in Nevada (+4.6%), which corresponded with the highest APC in oral cancer mortality (+4.6%). Subsequent studies regarding reduced rates of cigarette use due to smoking restrictions and bans have suggested that follow up studies may reveal changes in the incidence and mortality rates of oral and other related cancers. This study analysis revealed that oral cancer incidence rates are no longer increasing in Nevada and that mortality rates have started to decline, although not as rapidly as the overall national rates. However, rapid decreases in both the incidence and mortality from esophageal and lung cancer were observed in Nevada, which strongly suggest the corresponding changes in oral cancer may be part of a larger epidemiologic shift resulting from improved public health policies that include indoor smoking restrictions and bans.

Risk factors associated with cardiovascular disease among adult Nevadans.

OBJECTIVE: Cardiovascular disease (CVD) remains the number one cause of death in the US and Nevada is ranked 11th highest for CVD mortality. The study sought to examine the association between self-reported risk factors and CVD presence among adult Nevadans, between years 2011 and 2017. METHODS: This is a cross-sectional, population-based study that utilized the 2011 and 2017 Nevada Behavioral Risk Factor Surveillance System data. Data were analyzed between 2019 and 2020. RESULTS: A total of 5,493 and 3,764 subjects in 2011 and 2017, respectively were included. BMI (overweight/obesity) remained the most prevalent CVD risk factor. The second most common CVD risk factor was high cholesterol, followed by hypertension. Compared to females, males were 1.64 times more likely to have reported CVD in 2011, which increased to 1.92 in 2017. Compared to non-smokers, everyday smokers were 1.96 times more likely in 2011 and 3.62 times more likely in 2017. Individuals with high cholesterol status were 2.67 times more likely to have reported CVD compared to those with normal levels in 2011. In 2011, individuals with hypertension were 3.74 times more likely to have reported CVD compared to those who did not have hypertension. This relationship increased its magnitude of risk to 6.18 times more likely in 2017. In 2011, individuals with diabetes were 2.90 times more likely to have reported CVD compared to those without the condition. CONCLUSIONS: Public health and healthcare providers need to target preventable cardiovascular risk factors and develop recommendations and strategies locally, nationally, and globally.

Immune and sex-biased gene expression in the threatened Mojave desert tortoise, Gopherus agassizii.

The immune system of ectotherms, particularly non-avian reptiles, remains poorly characterized regarding the genes involved in immune function, and their function in wild populations. We used RNA-Seq to explore the systemic response of Mojave desert tortoise (Gopherus agassizii) gene expression to three levels of Mycoplasma infection to better understand the host response to this bacterial pathogen. We found over an order of magnitude more genes differentially expressed between male and female tortoises (1,037 genes) than differentially expressed among immune groups (40 genes). There were 8 genes differentially expressed among both variables that can be considered sex-biased immune genes in this tortoise. Among experimental immune groups we find enriched GO biological processes for cysteine catabolism, regulation of type 1 interferon production, and regulation of cytokine production involved in immune response. Sex-biased transcription involves iron ion transport, iron ion homeostasis, and regulation of interferon-beta production to be enriched. More detailed work is needed to assess the seasonal response of the candidate genes found here. How seasonal fluctuation of testosterone and corticosterone modulate the immunosuppression of males and their susceptibility to Mycoplasma infection also warrants further investigation, as well as the importance of iron in the immune function and sex-biased differences of this species. Finally, future transcriptional studies should avoid drawing blood from tortoises via subcarapacial venipuncture as the variable aspiration of lymphatic fluid will confound the differential expression of genes.

Origin of tungsten and geochemical controls on its occurrence and mobilization in shallow sediments from Fallon, Nevada, USA.

Tungsten (W) occurrence and speciation was investigated in sediments collected from Fallon, Nevada where previous studies have linked elevated W levels in human body fluids to an unusual cluster of childhood leukemia cases. The speciation of sedimentary W was determined by µ-XRF mapping and µ-XANES. The W content of the analyzed surface sediments ranged between 81 and 25,908 mg/kg, which is significantly higher than the W content in deeper sediments which ranged from 37 to 373 mg/kg at 30 cm depth. The µ-XANES findings reveal that approximately 20-50% of the total W in the shallow sediment occurs in the metallic form (W0); the rest occurs in the oxide form (WVIO3). Because W0 does not occur naturally, its elevated concentrations in surface sediments point toward a possible local anthropogenic origin. The oxidation of metallic W0 with meteoric waters likely leads to the formation of WVIO3. The chief water-soluble W species was identified as WO42- by chromatographic separation and speciation modeling. These results led us to postulate that W0 particles from a currently unknown but local source(s) is (are) deposited onto the soils and/or surface sediments. The W0 in interaction with meteoric water is oxidized to WVIO3, and as these sediment-water interactions progress, WO42- is formed in the water at pH ∼7. Under pH < 7, and sufficient W concentrations, tungstate tends to polymerize, and polymerized species are less likely to adsorb onto sediments. Polymerized species have lower affinity than monomers, which leads to enhanced mobility of W.

Beyond Barnwell: Applying lessons learned from the Barnwell site to other historic underground nuclear tests at Pahute Mesa to understand radioactive gas-seepage observations.

An underground nuclear explosion (UNE) generates radioactive gases that can be transported through fractures to the ground surface over timescales of hours to months. If detected, the presence of particular short-lived radionuclides in the gas can provide strong evidence that a recent UNE has occurred. By drawing comparisons between sixteen similar historical U.S. UNEs where radioactive gas was or was not detected, we identified factors that control the occurrence and timing of breakthrough at the ground surface. The factors that we evaluated include the post-test atmospheric conditions, local geology, and surface geology at the UNE sites. The UNEs, all located on Pahute Mesa on the Nevada National Security Site (NNSS), had the same announced yield range (20-150 kt), similar burial depths in the unsaturated zone, and were designed and performed by the same organization during the mid-to-late 1980s. Results of the analysis indicate that breakthrough at the ground surface is largely controlled by a combination of the post-UNE barometric pressure changes in the months following the UNE, and the volume of air-filled pore space above the UNE. Conceptually simplified numerical models of each of the 16 historical UNEs that include these factors successfully predict the occurrence (5 of the UNEs) or lack of occurrence (remaining 11 UNEs) of post-UNE gas seepage to the ground surface. However, the data analysis and modeling indicates that estimates of the meteorological conditions and of the post-UNE, site-specific subsurface environment including air-filled porosity, in combination, may be necessary to successfully predict late-time detectable gas breakthrough for a suspected UNE site.