During September to December 2021, school mask policies to mitigate SARS-CoV-2 transmission varied throughout the US. We compared infection-induced seroprevalence estimates and estimated seroconversion among children residing in areas with and without school mask requirements. We estimated infection-induced seroprevalence among children in three age groups (5-17, 5-11, and 12-17 years) in areas with and without school district mask requirements for two time points: September 1-30, 2021 and December 15, 2021 to January 14, 2022. Robust Poisson regression models estimated population seroconversion over the semester among initially seronegative children. Permutation tests assessed for significant differences in the estimated population seroconversion due to incident infections by school district mask policy. Residing in an area with no school mask requirement was associated with higher infection-induced seroprevalence among children aged 5-17 years (adjusted prevalence ratio [aPR] = 1.18, 95% confidence interval [CI]: 1.10, 1.26), and those aged 5-11 years (aPR) = 1.21, 95% CI: 1.10, 1.32) and those aged 12-17 years (aPR = 1.16, 95% CI: 1.07, 1.26), compared with areas requiring masks in school. Estimated population seroconversion during the semester was also significantly higher among children in districts without mask policies than those with school mask requirements among all age groups (5-17 years: 23.7% vs 18.1%, P < 0.001; 5-11 years: 6.4% vs 4.5%, P = 0.002;12-17 years: 27.2% vs 21.0%, P < 0.001). During the U.S. Fall 2021 semester, areas with school mask requirements had lower infection-induced seroprevalence and an estimated lower proportion of seroconversion due to incident infection among school-aged children compared with areas without school mask requirements; causality cannot necessarily be inferred from these associations. IMPORTANCE: During the U.S. Fall 2021 school semester, the estimated proportion of previously uninfected school-aged children who experienced a first infection with SARS-CoV-2 was lower in areas where public school district policies required masks for all staff and students compared with areas where the school districts had no mask requirements. Because children are more likely than adults to experience asymptomatic or mild SARS-CoV-2 infections, the presence of infection-induced antibodies is a more accurate measure of infection history than clinical testing. The proportion of children with these antibodies (i.e., seroprevalence) can improve our understanding of SARS-CoV-2 by detecting more infections and eliminating potential bias due to local testing and reporting practices. Enhanced robustness of surveillance for respiratory infections in children, including records of mitigation policies in communities and schools, as well as seroprevalence data, would establish a better evidence base for policy decisions and response measures during future respiratory outbreaks.

Shale gas wells located in longwall chain pillars are subject to longwall-induced subsurface ground movements. Longwall mining on either side of the chain pillars can induce deformations in gas well casings. Excessive casing deformations could diminish casing integrity so that intrusive shale gas might leak into the longwall mine jeopardizing mine safety. This study investigated longwall-induced casing deformations of eight shale gas wells in the chain pillars between two adjacent longwall panels in the Pittsburgh coal seam under a cover depth of 314 m. The casing deformations were measured with a 56-arm caliper after each longwall face passed the gas well pad. Casing deformations were detected at ten locations below the surface after first panel mining, and the maximum casing deformation of 1.27 cm occurred at a 184-m depth. After second panel mining, the caliper survey showed that casing deformation locations remained the same, but generally the deformations increased slightly. The maximum deformation at the 184-m depth increased from 1.27 to 1.5 cm. The eight shale gas wells were also modeled by the FLAC3D modeling technique. The casing deformations predicted by the FLAC3D model were compared with the caliper survey results. The modeling predictions were in a good agreement with the caliper measurements in terms of deformation level and locations. The modeling results suggested that the gas well setback distance to the longwall gob would affect casing deformations, and that casing deformations can be minimized if gas wells are located around the center of the abutment pillar. The study showed that longwall-induced casing deformations occur at the same weak/strong rock interfaces after both first and second panel mining. The study also showed that, under deep cover, casing deformations above the coal seam horizon are smaller than those under shallow cover. Under deep cover, the production casing deformations evaluated in this study were demonstrated to be minimized by locating gas wells at the center of the chain pillars and by leaving the production casing uncemented from the surface to below the coal seam. © This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2024.

OBJECTIVE: Early treatment of autism spectrum disorder (ASD) can improve developmental outcomes. Children with ASD from minority families often receive services later. We explored factors related to child's age at time of mother's first concerns about child's development and subsequent time to service initiation among children with ASD. METHODS: Analysis included 759 preschool-age children classified with ASD based on comprehensive evaluations. Factors associated with retrospectively reported child age at time of first maternal concern and subsequent time to service initiation were investigated using multiple linear regression and Cox proportional hazards. RESULTS: Earlier maternal concern was associated with multiparity, ≥1 child chronic condition, externalizing behaviors, and younger gestational age, but not race/ethnicity. Time to service initiation was longer for children of non-Latino Black or other than Black or White race and higher developmental level and shorter for children with ≥1 chronic condition and older child age at first maternal concern. CONCLUSION: Parity, gestational age, and child health and behavior were associated with child age at first maternal concern. Knowledge of child development in multiparous mothers may allow them to recognize potential concerns earlier, suggesting that first time parents may benefit from enhanced education about normal development. Race/ethnicity was not associated with child's age when mothers recognized potential developmental problems; hence, it is unlikely that awareness of ASD symptoms causes racial/ethnic disparities in initiation of services. Delays in time to service initiation among children from racial/ethnic minority groups highlight the need to improve their access to services as soon as developmental concerns are recognized.

BACKGROUND: Because COVID-19 case data do not capture most SARS-CoV-2 infections, the actual risk of severe disease and death per infection is unknown. Integrating sociodemographic data into analysis can show consequential health disparities. METHODS: Data were merged from September 2020 to November 2021 from 6 national surveillance systems in matched geographic areas and analyzed to estimate numbers of COVID-19-associated cases, emergency department visits, and deaths per 100 000 infections. Relative risks of outcomes per infection were compared by sociodemographic factors in a data set including 1490 counties from 50 states and the District of Columbia, covering 71% of the US population. RESULTS: Per infection with SARS-CoV-2, COVID-19-related morbidity and mortality were higher among non-Hispanic American Indian and Alaska Native persons, non-Hispanic Black persons, and Hispanic or Latino persons vs non-Hispanic White persons; males vs females; older people vs younger; residents in more socially vulnerable counties vs less; those in large central metro areas vs rural; and people in the South vs the Northeast. DISCUSSION: Meaningful disparities in COVID-19 morbidity and mortality per infection were associated with sociodemography and geography. Addressing these disparities could have helped prevent the loss of tens of thousands of lives.

Traffic-related pedestrian deaths in the United States reached a 40-year high in 2021. Each year, pedestrians also suffer nonfatal traffic-related injuries requiring medical treatment. Near real-time emergency department visit data from CDC's National Syndromic Surveillance Program during January 2021-December 2023 indicated that among approximately 301 million visits identified, 137,325 involved a pedestrian injury (overall visit proportion = 45.62 per 100,000 visits). The proportions of visits for pedestrian injury were 1.53-2.47 times as high among six racial and ethnic minority groups as that among non-Hispanic White persons. Compared with persons aged ≥65 years, proportions among those aged 15-24 and 25-34 years were 2.83 and 2.61 times as high, respectively. The visit proportion was 1.93 times as high among males as among females, and 1.21 times as high during September-November as during June-August. Timely pedestrian injury data can help collaborating federal, state, and local partners rapidly monitor trends, identify disparities, and implement strategies supporting the Safe System approach, a framework for preventing traffic injuries among all road users.

BACKGROUND: Physical activity for any purpose counts toward meeting Physical Activity Guidelines (PAG). However, national surveillance systems traditionally focus on leisure-time physical activity. There is an incomplete understanding of the association between meeting PAG in leisure time and occupation activity level among US workers. METHODS: We used cross-sectional 2020 National Health Interview Survey data to examine US adults aged 18-64 years who worked the week before the survey (n = 14,814). We estimated the proportion meeting aerobic and muscle-strengthening PAG in leisure time by occupation activity level (low, intermediate, and high). Using logistic regression, we examined the association between meeting PAG in leisure time and occupation activity level, adjusted for sociodemographic characteristics and stratified by hours worked. We compared the sociodemographic characteristics of adults working ≥40 hours (the previous week) in high-activity occupations to those in low- or intermediate-activity occupations. RESULTS: Adults working in high-activity occupations were less likely to meet PAG in leisure time (26.1% [24.3-28.1]) versus those in low-activity (30.6% [29.1-32.2], P < .01) or intermediate-activity (32.4% [30.8-34.2]) occupations. In stratified, adjusted models, adults working ≥40 hours in low- and intermediate-activity occupations were 13% and 20%, respectively, more likely to meet PAG in leisure time versus those in high-activity occupations. Among those working ≥40 hours, adults in high-activity occupations were more likely to be Hispanic or Latino, male, younger, and have a high school education or lower compared with those in less active occupations. CONCLUSION: Traditional surveillance may underestimate meeting PAG among people working in high-activity occupations, potentially disproportionately affecting certain groups.

Palau had no reported evidence of COVID-19 community spread until January 2022. We chart reviewed hospitalized patients who had a positive SARS-CoV-2 test result during early community transmission. Booster vaccinations and early outpatient treatment decreased hospitalizations. Inadequate hospital infection control practices contributed to iatrogenic COVID-19 and preventable deaths.

In 2016, a 3.7-ML magnitude event caused by mining activity occurred at a longwall mine in southwestern Virginia which was recorded by the United States Geological Survey (USGS) and felt by local residents. The event was the largest of its kind since a global mine design change by the operator was instituted in 2008 following three large events in 2005, 2006, and 2007 (3.4, 4.3, and 3.4 Moment Magnitude (Mw), respectively). Two of the three pre-2008 events (2005 and 2007) damaged ventilation controls in the mine which fueled a mine fire. In 2016, the mine’s management requested researchers from the National Institute for Occupational Safety and Health (NIOSH) to access geological data and determine what parameters could possibly lead to events of a magnitude of 1.0 ML or greater. Evaluation of 2152 geological data points and modeling revealed three major geological factors in common with the majority of the 181 recorded +1.0 ML events from 2009 through 2016. Three levels of seismic potential were identified as follows: Low potential (1.0+ ML): overburden greater than 579 mModerate potential (1.5+ ML): overburden greater than 579.12 m and 6.1–12.2 m of sandstone within 15.24 m above the top of the Pocahontas 3 coal seamElevated potential (3.0+ ML): overburden greater than 579.12 m, 6.1–12.2 m of sandstone within 15.24 m above the coal seam, and caving height of less than 4.5 m above the coal seam These three factors were used to create a seismic forecast map that produced an accuracy of 74–89% for 1.0 ML or greater events, 72% accuracy for 1.5 ML or greater events, and 100% accuracy for 3.0ML or greater events based on seismic history [1]. The map was created to not only show how geological data can be combined to understand why a mining-related seismic event occurred in a particular area, but how the map could be used to forecast potential seismic areas in future mining. This paper is an update to report the accuracy forecasting large seismic events in areas mined since the map was originally published in 2017 and how the map has helped improve miner safety and health based on its implementation. New changes to the forecasting process include implementing a change to the moderate potential criteria to expand the sandstone thickness to 4.6–12.2 m and decreasing the location error from a 91-m buffer to a 10% (58 m) elevation error based on the first overburden thickness threshold of 579 m. Since the first seismic forecasting map was published, the map has correctly forecasted 54–71% of 115 total 1.0–1.4 ML events, 69–83% of 49 total 1.5–1.9 ML events, and 88% of 9 total 2.0 ML or above events in previously unmined areas. © 2023, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.

The COVID-19 pandemic may have disrupted people's work-life patterns and access to places to be physically active. Behavioral Risk Factor Surveillance System data were analyzed to assess changes in self-reported leisure-time physical inactivity. The results showed that prevalence of inactivity among US adults decreased 0.7 percentage points (95% CI: -1.2 to -0.3), from 24.5% in 2018 to 23.8% in 2020, and the greatest decreases were observed among rural-dwelling women, rural-dwelling men, and non-Hispanic White women. These findings highlight a need to understand and address factors that lead to differential changes in leisure-time physical inactivity across subpopulations during public health emergencies.

Repeating the BinaxNOW antigen test for SARS-CoV-2 by two groups of readers within 30 minutes resulted in high concordance (98.9%) in 2,110 encounters. BinaxNOW test sensitivity was 77.2% (258/334) compared to real-time reverse transcription-polymerase chain reaction. Repeating antigen testing on the same day did not significantly improve test sensitivity while specificity remained high.Competing Interest StatementThe authors have declared no competing interest.Funding StatementThis work was funded by the Centers for Disease Control and Prevention.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy. See e.g., 45 C.F.R. part 46.102(l)(2), 21 C.F.R. part 56; 42 U.S.C. 241(d); 5 U.S.C. 552a; 44 U.S.C. 3501 et seq.All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesData will be made available upon reasonable request.

During the COVID-19 pandemic, the U.S. firearm homicide rate increased by nearly 35%, and the firearm suicide rate remained high during 2019-2020 (1). Provisional mortality data from the National Vital Statistics System indicate that rates continued to increase in 2021: the rates of firearm homicide and firearm suicide in 2021 were the highest recorded since 1993 and 1990, respectively (2). Firearm injuries treated in emergency departments (EDs), the primary setting for the immediate medical treatment of such injuries, gradually increased during 2018-2019 (3); however, more recent patterns of ED visits for firearm injuries, particularly during the COVID-19 pandemic, are unknown. Using data from the National Syndromic Surveillance Program (NSSP),* CDC examined changes in ED visits for initial firearm injury encounters during January 2019-December 2022, by year, patient sex, and age group. Increases in the overall weekly number of firearm injury ED visits were detected at certain periods during the COVID-19 pandemic. One such period during which there was a gradual increase was March 2020, which coincided with both the declaration of COVID-19 as a national emergency(†) and a pronounced decrease in the total number of ED visits. Another increase in firearm injury ED visits occurred in late May 2020, concurrent with a period marked by public outcry related to social injustice and structural racism (4), changes in state-level COVID-19-specific prevention strategies,(§) decreased engagement in COVID-19 mitigation behaviors (5), and reported increases in some types of crime (4). Compared with 2019, the average number of weekly ED visits for firearm injury was 37% higher in 2020, 36% higher in 2021, and 20% higher in 2022. A comprehensive approach is needed to prevent and respond to firearm injuries in communities, including strategies that engage community and street outreach programs, implement hospital-based violence prevention programs, improve community physical environments, enhance secure storage of firearms, and strengthen social and economic supports.

IMPORTANCE: Firearm homicides are a major public health concern; lack of timely mortality data presents considerable challenges to effective response. Near real-time data sources offer potential for more timely estimation of firearm homicides. OBJECTIVE: To estimate near real-time burden of weekly and annual firearm homicides in the US. DESIGN, SETTING, AND PARTICIPANTS: In this prognostic study, anonymous, longitudinal time series data were obtained from multiple data sources, including Google and YouTube search trends related to firearms (2014-2019), emergency department visits for firearm injuries (National Syndromic Surveillance Program, 2014-2019), emergency medical service activations for firearm-related injuries (biospatial, 2014-2019), and National Domestic Violence Hotline contacts flagged with the keyword firearm (2016-2019). Data analysis was performed from September 2021 to September 2022. MAIN OUTCOMES AND MEASURES: Weekly estimates of US firearm homicides were calculated using a 2-phase pipeline, first fitting optimal machine learning models for each data stream and then combining the best individual models into a stacked ensemble model. Model accuracy was assessed by comparing predictions of firearm homicides in 2019 to actual firearm homicides identified by National Vital Statistics System death certificates. Results were also compared with a SARIMA (seasonal autoregressive integrated moving average) model, a common method to forecast injury mortality. RESULTS: Both individual and ensemble models yielded highly accurate estimates of firearm homicides. Individual models' mean error for weekly estimates of firearm homicides (root mean square error) varied from 24.95 for emergency department visits to 31.29 for SARIMA forecasting. Ensemble models combining data sources had lower weekly mean error and higher annual accuracy than individual data sources: the all-source ensemble model had a weekly root mean square error of 24.46 deaths and full-year accuracy of 99.74%, predicting the total number of firearm homicides in 2019 within 38 deaths for the entire year (compared with 95.48% accuracy and 652 deaths for the SARIMA model). The model decreased the time lag of reporting weekly firearm homicides from 7 to 8 months to approximately 6 weeks. CONCLUSIONS AND RELEVANCE: In this prognostic study of diverse secondary data on machine learning, ensemble modeling produced accurate near real-time estimates of weekly and annual firearm homicides and substantially decreased data source time lags. Ensemble model forecasts can accelerate public health practitioners' and policy makers' ability to respond to unanticipated shifts in firearm homicides.

At least 100,000 persons in the United States experience a fatal or nonfatal firearm injury each year.* CDC examined rates of firearm injury emergency department (ED) visits by community social vulnerability using data from CDC's Firearm Injury Surveillance Through Emergency Rooms (FASTER) program.() ED visit data, shared with CDC's National Syndromic Surveillance Program (NSSP)() during 2018-2021, were analyzed for 647 counties in 10 FASTER-funded jurisdictions.() County-level social vulnerability data were obtained from the 2018 Social Vulnerability Index (SVI).** Rates of ED visits for firearm injuries (number of firearm injury ED visits per 100,000 ED visits) were calculated across tertile levels of social vulnerability. Negative binomial regression models were used to estimate rate ratios (RRs) and associated 95% CIs comparing rates of ED visits across social vulnerability levels. During 2018-2021, compared with rates in counties with low overall social vulnerability, the firearm injury ED visit rate was 1.34 times as high in counties with medium social vulnerability and 1.80 times as high in counties with high social vulnerability. Similar patterns were observed for the SVI themes of socioeconomic status and housing type and transportation, but not for the themes of household composition and disability status or racial and ethnic minority status and language proficiency. More timely data() on firearm injury ED visits by social vulnerability can help identify communities disproportionately experiencing elevated firearm injury rates. States and communities can use the best available evidence to implement comprehensive prevention strategies that address inequities in the social and structural conditions that contribute to risk for violence, including creating protective community environments, strengthening economic supports, and intervening to reduce harms and prevent future risk (e.g., with hospital-based violence intervention programs) (1,2).

The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a post-mining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64°, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457-m wide and 3657-m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones in longwall gobs. © 2022, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.

Fresh air ventilation has been identified as a widely accepted engineering control effective at diluting air contaminants in enclosed environments. The goal of this study was to evaluate the effects of selected ventilation measures on air change rates in school buses. Air changes per hour (ACH) of outside air were measured using a well-established carbon dioxide (CO(2)) tracer gas decay method. Ventilation was assessed while stationary and while traversing standardized route during late autumn/winter months in Colorado. Seven CO(2) sensors located at the driver's seat and at passenger seats in the front, middle, and rear of the bus yielded similar and consistent measurements. Buses exhibited little air exchange in the absence of ventilation (ACH =0.13 when stationary; ACH =1.85 when mobile). Operating the windshield defroster to introduce fresh outside air increased ACH by approximately 0.5-1 ACH during mobile and stationary phases. During the mobile phase (average speed of 23 miles per hour (mph) ), the combination of the defroster and two open ceiling hatches (with a powered fan on the rear hatch) yielded an ACH of approximately 9.3 ACH. A mobile phase ACH of 12.4 was achieved by the combination of the defroster, ceiling hatches, and six passenger windows open 2 inches in the middle area of the bus. A maximum mobile phase ACH of 22.1 was observed by using the defroster, open ceiling hatches, driver window open 4 inches, and every other passenger window open 2 inches. For reference, ACHs recommended in patient care settings where patients are being treated for airborne infectious diseases range from 6 to ≥12 ACHs. The results indicate that practical ventilation protocols on school buses can achieve air change rates thought to be capable of reducing airborne viral transmission to the bus driver and student passengers during the COVID-19 pandemic.

The association of autism spectrum disorder (ASD) with self-reported maternal cannabis use from 3 months pre-conception to delivery ("peri-pregnancy") was assessed in children aged 30-68 months, born 2003 to 2011. Children with ASD (N = 1428) were compared to children with other developmental delays/disorders (DD, N = 1198) and population controls (POP, N = 1628). Peri-pregnancy cannabis use was reported for 5.2% of ASD, 3.2% of DD and 4.4% of POP children. Adjusted odds of peri-pregnancy cannabis use did not differ significantly between ASD cases and DD or POP controls. Results were similar for any use during pregnancy. However, given potential risks suggested by underlying neurobiology and animal models, further studies in more recent cohorts, in which cannabis use and perception may have changed, are needed.

Native Hawaiian and Pacific Islander populations have been disproportionately affected by COVID-19 (1-3). Native Hawaiian, Pacific Islander, and Asian populations vary in language; cultural practices; and social, economic, and environmental experiences,(†) which can affect health outcomes (4).(§) However, data from these populations are often aggregated in analyses. Although data aggregation is often used as an approach to increase sample size and statistical power when analyzing data from smaller population groups, it can limit the understanding of disparities among diverse Native Hawaiian, Pacific Islander, and Asian subpopulations(¶) (4-7). To assess disparities in COVID-19 outcomes among Native Hawaiian, Pacific Islander, and Asian populations, a disaggregated, descriptive analysis, informed by recommendations from these communities,** was performed using race data from 21,005 COVID-19 cases and 449 COVID-19-associated deaths reported to the Hawaii State Department of Health (HDOH) during March 1, 2020-February 28, 2021.(††) In Hawaii, COVID-19 incidence and mortality rates per 100,000 population were 1,477 and 32, respectively during this period. In analyses with race categories that were not mutually exclusive, including persons of one race alone or in combination with one or more races, Pacific Islander persons, who account for 5% of Hawaii's population, represented 22% of COVID-19 cases and deaths (COVID-19 incidence of 7,070 and mortality rate of 150). Native Hawaiian persons experienced an incidence of 1,181 and a mortality rate of 15. Among subcategories of Asian populations, the highest incidences were experienced by Filipino persons (1,247) and Vietnamese persons (1,200). Disaggregating Native Hawaiian, Pacific Islander, and Asian race data can aid in identifying racial disparities among specific subpopulations and highlights the importance of partnering with communities to develop culturally responsive outreach teams(§§) and tailored public health interventions and vaccination campaigns to more effectively address health disparities.

We examined disparities in cumulative incidence of severe acute respiratory syndrome coronavirus 2 by race/ethnicity, age, and sex in the United States during January 1-October 1, 2020. Hispanic/Latino and non-Hispanic Black, American Indian/Alaskan Native, and Native Hawaiian/other Pacific Islander persons had a substantially higher incidence of infection than non-Hispanic White persons.

Ground falls in longwall gateroad entries remain a concern in modern longwall operations. The gateroads are subject to changing horizontal and vertical ground stress induced by longwall extraction. These stress changes can result in failure of the strata around an entry leading to large deformations of the entry roof, floor, and ribs. The gateroad support systems are required to control the failed strata while maintaining safe access to the longwall face and unimpeded ventilation. This paper presents research that was conducted to better understand the stability issues in gateroad excavations and to develop procedures for evaluating support and layout alternatives for longwall gateroads. Using the results of a field-monitoring program and numerical model analysis of case histories, a conceptual model of gateroad support needs was developed. The conceptual model formed the basis for developing a set of equations that can be used to estimate likely roof sag and support loading for given roof geology and longwall-induced loading conditions. The developed equations were used to compare predicted gateroad stability to field study results, showing satisfactory agreement. The calculation procedures are used to demonstrate their application in assessing support alternatives at a case study mine. It is concluded that the developed analysis procedures provide realistic assessments of likely ground stability and can be used to evaluate alternative gateroad support systems at operating longwall mines. © 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.

Repeating the BinaxNOW antigen test for SARS-CoV-2 by two groups of readers within 30 minutes resulted in high concordance (98.9%) in 2,110 encounters. BinaxNOW test sensitivity was 77.2% (258/334) compared to real-time reverse transcription-polymerase chain reaction. Same day antigen testing did not significantly improve test sensitivity while specificity remained high.

The COVID-19 pandemic has disproportionately affected racial and ethnic minority groups in the United States. Whereas racial and ethnic disparities in severe COVID-19-associated outcomes, including mortality, have been documented (1-3), less is known about population-based disparities in infection with SARS-CoV-2, the virus that causes COVID-19. In addition, although persons aged <30 years account for approximately one third of reported infections,(§) there is limited information on racial and ethnic disparities in infection among young persons over time and by sex and age. Based on 689,672 U.S. COVID-19 cases reported to CDC's case-based surveillance system by jurisdictional health departments, racial and ethnic disparities in COVID-19 incidence among persons aged <25 years in 16 U.S. jurisdictions(¶) were described by age group and sex and across three periods during January 1-December 31, 2020. During January-April, COVID-19 incidence was substantially higher among most racial and ethnic minority groups compared with that among non-Hispanic White (White) persons (rate ratio [RR] range = 1.09-4.62). During May-August, the RR increased from 2.49 to 4.57 among non-Hispanic Native Hawaiian and Pacific Islander (NH/PI) persons but decreased among other racial and ethnic minority groups (RR range = 0.52-2.82). Decreases in disparities were observed during September-December (RR range = 0.37-1.69); these decreases were largely because of a greater increase in incidence among White persons, rather than a decline in incidence among racial and ethnic minority groups. NH/PI, non-Hispanic American Indian or Alaska Native (AI/AN), and Hispanic or Latino (Hispanic) persons experienced the largest persistent disparities over the entire period. Ensuring equitable and timely access to preventive measures, including testing, safe work and education settings, and vaccination when eligible is important to address racial/ethnic disparities.

This paper presents the results of a unique study conducted by the National Institute for Occupational Safety and Health (NIOSH) from 2016 to 2019 to evaluate the effects of longwall-induced subsurface deformations on shale gas well casing integrity and underground miner safety and health. At both deep-cover and shallow-cover instrumentation sites, surface subsidence measurements, subsurface in-place inclinometer measurements, and underground pillar pressure measurements were conducted as longwall panels were mined. Comparisons of the deep-cover and shallow-cover test site results with those from a similar study under medium cover reveal an interesting longwall-induced response scenario. Under shallow and medium covers, measured horizontal displacements within the abutment pillar are one order of magnitude higher than those measured under deep cover. On the other hand, measured vertical compressions under deep cover are one order of magnitude higher than those under shallow and medium covers. However, FLAC3D simulations of the casings indicate that, in all three cases, the P-110 production casings remain intact under longwall-induced deformations and compressions, which has serious implications for future mine design in areas where shale gas wells have been drilled ahead of mining.

Coal mines are continuously seeking to determine the performance of entries with different ground control products and installation methods. There are many factors that impact how an entry will perform which include but are not limited to geology, overburden, bolting type and pattern, and mine design. At the National Institute for Occupational Safety and Health (NIOSH), research has been instituted to examine the relationship of the parts of a coal mine entry as a system and not as individual components. To study this relationship, the first step in this study was to create a numeric rating system that accurately reflects visual observations of the mine entry and is easy to implement. NIOSH researchers devised this rating system to improve upon previous ideas, offering increased flexibility which can be incorporated into an overall entry condition that offers different levels of confidence based on the user's time devoted to the inspection. This new entry rating system was implemented at three different mines over varying periods of time to evaluate the ground response to the geology, bolt installation pattern, stress changes by mining, overburden, and time dependency.

Bleeder entries are critically important to longwall mining for the moving of supplies, personnel, and the dilution of mine air contaminants. By design, these entries must stay open for many years for ventilation. Standing supports in moderate cover bleeder entries were observed, numerically modeled, and instrumented by researchers at the National Institute for Occupational Safety and Health (NIOSH). The measurements of the installed borehole pressure cells (BPCs), standing support load cells and convergence meters, and roof extensometers are presented in this paper in addition to the numerical modeling results and visual observations made by the NIOSH researchers in the bleeder entries. The results include the effects of multiple panels being extracted in close proximity to the instrumented site as well as over one and a half years of aging. As expected, standing supports closer to the longwall gob showed the greatest load and convergence. The roof sag appeared generally independent of the proximity to the longwall gob. The BPC readings were driven by both the proximity to the gob and the depth into the pillar. The results of this study demonstrated that the entry roof can respond independently of the pillar and standing support loading. In addition, the rear abutment stress experienced by this bleeder entry design was minimal. The closer the mine development, pillar, or supports are to the gob, the greater the applied load due to rear abutment stress.

Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable, but generally it is impractical due to the difficulty of gathering essential input data. However, applying a quantitative methodology to describe floor quality with a single number provides a practical estimate for preliminary assessment of floor stability. The coal mine floor rating (CMFR) system, developed by the University of New South Wales (UNSW), is a rock- mass classification system that provides an indicator for the competence of floor strata. The most significant components of the CMFR are uniaxial compressive strength and discontinuity intensity of floor strata. In addition to the competence of the floor, depth of cover and stress notch angle are input parameters used to assess the preliminary floor stability. In this study, CMFR methodology was applied to a Central Appalachian Coal Mine that intermittently experienced floor heave. Exploratory drill core data, overburden maps, and mine plans were utilized for the study. Additionally, qualitative data (failure/non-failure) on floor conditions of the mine entries near the core holes was collected and analyzed so that the floor quality and its relation to entry stability could be estimated by statistical methods. It was found that the current CMFR classification system is not directly applicable in assessing the floor stability of the Central Appalachian Coal Mine. In order to extend the applicability of the CMFR classification system, the methodology was modified. A calculation procedure of one of the CMFR classification system's components, the horizontal stress rating (HSR), was changed and new parameters were added to the HSR.

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel. The stress changes can result in significant deformation of the entries that may include roof sag, rib dilation, and floor heave. Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall face. This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives. The research included monitoring of ground and support interaction at several operating longwall mines in the U.S., analysis and calibration of numerical models that adequately represent the bedded rock mass, and observation of the support systems and their response to changes in stress. The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios. The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes. This information is then used to assess the ability of support systems to maintain the stability of the roof. The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall. The method is shown to produce realistic estimates of gateroad entry stability and support performance, allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

One of the most common critical areas of longwall mining in terms of ground stability are the gateroad and bleeder entries. These critical entries provide much-needed safe access for miners and allow for adequate ventilation required for dilution of hazardous airborne contaminants and must remain open during mining of a multi-panel district. This paper is focused on the stability of the longwall entries subjected to a single abutment load such as bleeders, first tailgate, and last headgate. First tailgate and last headgate are also referred to as blind headgate and tailgate. A study of a longwall district through conditions mapping, support evaluations, and numerical modeling was conducted and evaluated by researchers from the National Institute for Occupational Safety and Health (NIOSH). The condition mapping and support evaluations were performed on entries that spanned the previous five years of mining and relied on a diverse selection of supports to maintain the functionality of the entry. Numerical modeling was also conducted to evaluate various support types with further investigation and comparison to the condition mapping. The study demonstrated the importance of the abutment load decay versus distance from the gob edge, the potential for a reduction in material handling related injuries, as well as optimal usage of secondary and standing support.

Researchers from the National Institute for Occupational Safety and Health (NIOSH) are developing a coal pillar rib rating (CPRR) technique to measure the integrity of coal ribs. The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs. The CPRR utilizes four parameters: rib homogeneity, bedding condition, face cleat orientation with respect to entry direction, and rib height. All these parameters are measurable in the field. A rib data collecting procedure and a simple sheet to calculate the CPRR were developed. The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth. CPRR calculations were conducted for 22 surveyed solid coal ribs, mainly composed of coal units. Based on this study, the rib performance was classified into four categories. A preliminary minimum primary rib support density (PRSD) line was obtained from these surveyed cases. Two sample cases are presented that illustrate the data collection form and CPRR calculations.

The National Institute for Occupational Safety and Health (NIOSH) has previously established pillar design guidelines for shallow, flat-lying mines and single-level operations. Little guidance exists for ground control design in multiple-level stone mines, and understanding the interactions between levels would allow engineers to better select interburden thicknesses and the necessary amount of pillar columnization. To investigate these loading conditions in multiple-level environments, NIOSH has partnered with two separately operated multiple-level mines to study the stress interaction between the levels as undermining occurs. The first mine is located in Tennessee with up to a 243-m overburden and 7-m interburden thickness between levels. The second mine is located in Kentucky with a 304-m overburden and 26-m interburden thickness between levels. The monitoring program at these sites includes stressmeters and LiDAR for tracking stress redistributions and rock displacement in response to undermining. Monitoring is ongoing, but numerical modeling results show the expected interaction between levels.

Wearing masks is a CDC-recommended* approach to reduce the spread of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), by reducing the spread of respiratory droplets into the air when a person coughs, sneezes, or talks and by reducing the inhalation of these droplets by the wearer. On July 2, 2020, the governor of Kansas issued an executive order(†) (state mandate), effective July 3, requiring masks or other face coverings in public spaces. CDC and the Kansas Department of Health and Environment analyzed trends in county-level COVID-19 incidence before (June 1-July 2) and after (July 3-August 23) the governor's executive order among counties that ultimately had a mask mandate in place and those that did not. As of August 11, 24 of Kansas's 105 counties did not opt out of the state mandate(§) or adopted their own mask mandate shortly before or after the state mandate was issued; 81 counties opted out of the state mandate, as permitted by state law, and did not adopt their own mask mandate. After the governor's executive order, COVID-19 incidence (calculated as the 7-day rolling average number of new daily cases per 100,000 population) decreased (mean decrease of 0.08 cases per 100,000 per day; net decrease of 6%) among counties with a mask mandate (mandated counties) but continued to increase (mean increase of 0.11 cases per 100,000 per day; net increase of 100%) among counties without a mask mandate (nonmandated counties). The decrease in cases among mandated counties and the continued increase in cases in nonmandated counties adds to the evidence supporting the importance of wearing masks and implementing policies requiring their use to mitigate the spread of SARS-CoV-2 (1-6). Community-level mitigation strategies emphasizing wearing masks, maintaining physical distance, staying at home when ill, and enhancing hygiene practices can help reduce transmission of SARS-CoV-2.