Effects of heat strain on cognitive function among a sample of miners.

Heat stress is associated with workplace injuries, likely through a combination of fatigue, reduced cognitive function, and thermal discomfort. The purpose of this study was to evaluate four cognitive tasks for sensitivity to heat stress. Eight participants performed treadmill exercise followed by assessments of serial reaction time (RT), Stroop effect, verbal delayed memory, and continuous performance working memory in an environmental chamber. A control (21.1 °C) trial, and "Hot 1" and "Hot 2" (both 37.8 °C) trials were run sequentially on two separate days to evaluate the four cognitive tasks. Heat strain (comparing Hot 1 and Hot 2 with the control trial) resulted in impairments in the serial RT test response and Stroop accuracy. Delayed memory was impacted only in the Hot 2 trial compared with the control trial. Given the demonstrated impact of heat on cognitive processes relevant to workers' real-world functioning in the workplace, understanding how to assess and monitor vigilant attention in the workplace is essential.

Rapid Spread of SARS-CoV-2 in a State Prison After Introduction by Newly Transferred Incarcerated Persons - Wisconsin, August 14-October 22, 2020.

SARS-CoV-2, the virus that causes COVID-19, can spread rapidly in prisons and can be introduced by staff members and newly transferred incarcerated persons (1,2). On September 28, 2020, the Wisconsin Department of Health Services (DHS) contacted CDC to report a COVID-19 outbreak in a state prison (prison A). During October 6-20, a CDC team investigated the outbreak, which began with 12 cases detected from specimens collected during August 17-24 from incarcerated persons housed within the same unit, 10 of whom were transferred together on August 13 and under quarantine following prison intake procedures (intake quarantine). Potentially exposed persons within the unit began a 14-day group quarantine on August 25. However, quarantine was not restarted after quarantined persons were potentially exposed to incarcerated persons with COVID-19 who were moved to the unit. During the subsequent 8 weeks (August 14-October 22), 869 (79.4%) of 1,095 incarcerated persons and 69 (22.6%) of 305 staff members at prison A received positive test results for SARS-CoV-2. Whole genome sequencing (WGS) of specimens from 172 cases among incarcerated persons showed that all clustered in the same lineage; this finding, along with others, demonstrated that facility spread originated with the transferred cohort. To effectively implement a cohorted quarantine, which is a harm reduction strategy for correctional settings with limited space, CDC's interim guidance recommendation is to serial test cohorts, restarting the 14-day quarantine period when a new case is identified (3). Implementing more effective intake quarantine procedures and available mitigation measures, including vaccination, among incarcerated persons is important to controlling transmission in prisons. Understanding and addressing the challenges faced by correctional facilities to implement medical isolation and quarantine can help reduce and prevent outbreaks.

Patterns of Heat Strain Among a Sample of US Underground Miners.

OBJECTIVE: This study characterizes physiological measures of heat exposure among US underground miners. METHODS: Core body temperature measured by using ingestible sensors during subjects' normal work shifts was categorized into four temperature zones: less than 37.5 °C, 37.5 °C to less than 38 °C, 38 °C to less than 38.5 °C, and more than or equal to 38.5 °C. RESULTS: On average, subjects changed temperature zones 13.8 times per shift. Temperatures increased above the recommended limit of 38 °C nearly 5 times per shift for an average of 26 minutes each episode. CONCLUSIONS: Unlike previous heat stress research that reported only maximum and mean temperature measurements, this analysis demonstrates a dynamic pattern of physiologic heat strain, with core body temperatures changing frequently and exceeding the 38 °C limit multiple times per shift. Further research is needed on the impact of multiple short-term, intermittent heat exposures on miners.