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BACKGROUND: The risk of heat-related illness and death may continue to increase in many locations as a consequence of climate change, but information on the effectiveness of policies to protect populations from the adverse effects of excessive heat is limited. In 2009, the National Athletic Trainers' Association Inter-Association Task Force (NATA-IATF) released guidelines to reduce exertional heat illness (EHI) among U.S. high school athletes participating in preseason sports activities, including preseason practice sessions for American football. A subset of state high school athletic associations have implemented state-mandated guidelines consistent with the 2009 NATA-IATF recommendations, but their effectiveness for reducing preseason EHI is unknown. OBJECTIVES: This study examines the association between the enactment of state high school athletic association-mandated NATA-IATF guidelines and the rate of EHI among high school students during preseason American football practice sessions. METHODS: We performed a quasi-experimental interrupted time-series study of EHI during high school American football practices in the 2005/2006-2016/2017 school years. We estimated state-level EHI rates using High School Reporting Information Online injury and athlete-exposure data, and used generalized estimating equations Poisson regression models to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) comparing state-years with and without mandated NATA-IATF guidelines. State-level covariates included state-year-specific average August temperatures, yearly deviations from each state's August average temperature across the study period, and school year. RESULTS: Data were available for 455 state-years from 48 states, including 32 state-years (7.0%) from 8 states when mandated guidelines consistent with the NATA-IATF recommendations were implemented. During an estimated 2,697,089 athlete-exposures, 190 EHIs were reported. Estimated preseason EHI rates were lower during state-years with versus without mandated guidelines (adjusted IRR=0:45, 95% CI: 0.23, 0.87). CONCLUSIONS: Our findings suggest that high school athletes would benefit from enactment of the 2009 NATA-IATF guidelines. Similar analyses of the effectiveness of other public health policies to reduce adverse health effects from ambient heat are warranted. [ABSTRACT FROM AUTHOR]

Background: More than a decade of satellite observations offers global information about the trend and magnitude of human exposure to fine particulate matter (PM2.5). Objective: In this study, we developed improved global exposure estimates of ambient PM2.5 mass and trend using PM2.5 concentrations inferred from multiple satellite instruments. Methods: We combined three satellite-derived PM2.5 sources to produce global PM2.5 estimates at about 10 km × 10 km from 1998 through 2012. For each source, we related total column retrievals of aerosol optical depth to near-ground PM2.5 using the GEOS–Chem chemical transport model to represent local aerosol optical properties and vertical profiles. We collected 210 global groundbased PM2.5 observations from the literature to evaluate our satellite-based estimates with values measured in areas other than North America and Europe. Results: We estimated that global population-weighted ambient PM2.5 concentrations increased 0.55 μg/m3/year (95% CI: 0.43, 0.67) (2.1%/year; 95% CI: 1.6, 2.6) from 1998 through 2012. Increasing PM2.5 in some developing regions drove this global change, despite decreasing PM2.5 in some developed regions. The estimated proportion of the population of East Asia living above the World Health Organization (WHO) Interim Target-1 of 35 μg/m3 increased from 51% in 1998–2000 to 70% in 2010–2012. In contrast, the North American proportion above the WHO Air Quality Guideline of 10 μg/m3 fell from 62% in 1998–2000 to 19% in 2010–2012. We found significant agreement between satellite-derived estimates and ground-based measurements outside North America and Europe (r = 0.81; n = 210; slope = 0.68). The low bias in satellite-derived estimates suggests that true global concentrations could be even greater. Conclusions: Satellite observations provide insight into global long-term changes in ambient PM2.5 concentrations. Satellite-derived estimates and ground-based PM2.5 observations from this study are available for public use. [ABSTRACT FROM AUTHOR]