Background: Although the association between PM2.5 mass and mortality has been extensively studied, few national-level analyses have estimated mortality effects of PM2.5 chemical constituents. Epidemiologic studies have reported that estimated effects of PM2.5 on mortality vary spatially and seasonally. We hypothesized that associations between PM2.5 constituents and mortality would not vary spatially or seasonally if variation in chemical composition contributes to variation in estimated PM2.5 mortality effects.Objectives: We aimed to provide the first national, season-specific, and region-specific associations between mortality and PM2.5 constituents.Methods: We estimated short-term associations between nonaccidental mortality and PM2.5 constituents across 72 urban U.S. communities from 2000 to 2005. Using U.S. Environmental Protection Agency (EPA) Chemical Speciation Network data, we analyzed seven constituents that together compose 79–85% of PM2.5 mass: organic carbon matter (OCM), elemental carbon (EC), silicon, sodium ion, nitrate, ammonium, and sulfate. We applied Poisson time-series regression models, controlling for time and weather, to estimate mortality effects.Results: Interquartile range increases in OCM, EC, silicon, and sodium ion were associated with estimated increases in mortality of 0.39% [95% posterior interval (PI): 0.08, 0.70%], 0.22% (95% PI: 0.00, 0.44), 0.17% (95% PI: 0.03, 0.30), and 0.16% (95% PI: 0.00, 0.32), respectively, based on single-pollutant models. We did not find evidence that associations between mortality and PM2.5 or PM2.5 constituents differed by season or region.Conclusions: Our findings indicate that some constituents of PM2.5 may be more toxic than others and, therefore, regulating PM total mass alone may not be sufficient to protect human health.Citation: Krall JR, Anderson GB, Dominici F, Bell ML, Peng RD. 2013. Short-term exposure to particulate matter constituents and mortality in a national study of U.S. urban communities. Environ Health Perspect 121:1148–1153; http://dx.doi.org/10.1289/ehp.1206185

Background:Short-term exposure to ambient fine particulate matter (PM2.5) concentrations has been associated with increased mortality and morbidity. Determining which sources of PM2.5 are most toxic can help guide targeted reduction of PM2.5. However, conducting multicity epidemiologic studies of sources is difficult because source-specific PM2.5 is not directly measured, and source chemical compositions can vary between cities.Objectives:We determined how the chemical composition of primary ambient PM2.5 sources varies across cities. We estimated associations between source-specific PM2.5 and respiratory disease emergency department (ED) visits and examined between-city heterogeneity in estimated associations.Methods:We used source apportionment to estimate daily concentrations of primary source-specific PM2.5 for four U.S. cities. For sources with similar chemical compositions between cities, we applied Poisson time-series regression models to estimate associations between source-specific PM2.5 and respiratory disease ED visits.Results:We found that PM2.5 from biomass burning, diesel vehicle, gasoline vehicle, and dust sources was similar in chemical composition between cities, but PM2.5 from coal combustion and metal sources varied across cities. We found some evidence of positive associations of respiratory disease ED visits with biomass burning PM2.5; associations with diesel and gasoline PM2.5 were frequently imprecise or consistent with the null. We found little evidence of associations with dust PM2.5.Conclusions:We introduced an approach for comparing the chemical compositions of PM2.5 sources across cities and conducted one of the first multicity studies of source-specific PM2.5 and ED visits. Across four U.S. cities, among the primary PM2.5 sources assessed, biomass burning PM2.5 was most strongly associated with respiratory health.Citation:Krall JR, Mulholland JA, Russell AG, Balachandran S, Winquist A, Tolbert PE, Waller LA, Sarnat SE. 2017. Associations between source-specific fine particulate matter and emergency department visits for respiratory disease in four U.S. cities. Environ Health Perspect 125:97–103; http://dx.doi.org/10.1289/EHP271

The delineation of the interrelationships between cognitive and physical functioning in older adults is critical to determining pathways to disability. By using longitudinal data from 395 initially high-functioning, communitydwelling older women in Baltimore, Maryland, from the Women's Health and Aging Study II (from 1994 to 2006), we simultaneously assessed associations of cognition with later physical functioning and associations of physical functioning with later cognition. The analysis included measures of global cognition and 2 cognitive domains (executive functioning and memory), as well as 2 measures of physical functioning (a Short Physical Performance Battery and a 4-meter test of usual walking speed). We found the strongest bidirectional associations of memory with physical functioning and less evidence of associations of physical functioning with executive functioning and global cognition. For a 1-standard deviation increase in walking speed, subsequent memory increased by 0.08 standard deviations (95% confidence interval: (0.03, 0.13)). For a 1-standard deviation increase in memory, subsequent walking speed increased by 0.07 standard deviations (95% confidence interval: 0.03, 0.10). Associations were similar in magnitude for models using a Short Physical Performance Battery. We did not find evidence that associations between cognitive and physical functioning varied over time. Our results suggest that cognition, and particularly memory, is associated with subsequent physical functioning and vice versa.

Objective To evaluate the effect of (1) patient values as expressed by family members, and (2) a requirement to document patients’ functional prognosis on intensivists’ intention to discuss withdrawal of life support in a hypothetical family meeting. Design A 3-armed, randomized trial Setting 179 U.S. hospitals with training programs in critical care accredited by the Accreditation Council for Graduate Medical Education Subjects 630 intensivists recruited via e-mail invitation from a database of 1,850 eligible academic intensivists Interventions Each intensivist was randomized to review ten, on-line, clinical scenarios with a range of illness severities involving a hypothetical patient (Mrs. X). In control-group scenarios, the patient did not want continued life support without a reasonable chance of independent living. In the first experimental arm, the patient wanted life support regardless of functional outcome. In the second experimental arm, patient values were identical to the control group, but intensivists were required to record the patient’s estimated three-month functional prognosis Measurements and Main Results Response to the question: “Would you bring up the possibility of withdrawing life support with Mrs. X’s family?” answered using a five-point Likert scale. There was no effect of patient values on whether intensivists intended to discuss withdrawal of life support (P = 0.81), but intensivists randomized to record functional prognosis were 49% more likely (95% confidence interval: 20%–85%) to discuss withdrawal. Conclusions In this national, scenario-based, randomized trial, patient values had no effect on intensivists’ decisions to discuss withdrawal of life support with family. However, requiring intensivists to record patients’ estimated 3-month functional outcome substantially increased their intention to discuss withdrawal.