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Background: The southeastern United States consistently has high salmonellosis incidence, but disease drivers remain unknown. Salmonella is regularly detected in this region's natural environment, leading to numerous exposure opportunities. Rainfall patterns may impact the survival/transport of environmental Salmonella in ways that can affect disease transmission. Objectives: This study investigated associations between short-term precipitation (extreme rainfall events) and longer- term precipitation (rainfall conditions antecedent to these extreme events) on salmonellosis counts in the state of Georgia in the United States. Methods: For the period 1997-2016, negative binomial models estimated associations between weekly county-level extreme rainfall events (>90th percentile of daily rainfall) and antecedent conditions (8-week precipitation sums, categorized into tertiles) and weekly county-level salmonellosis counts. Results: In Georgia's Coastal Plain counties, extreme and antecedent rainfall were associated with significant differences in salmonellosis counts. In these counties, extreme rainfall was associated with a 5% increase in salmonellosis risk (95% CI: 1%, 10%) compared with weeks with no extreme rainfall. Antecedent dry periods were associated with a 9% risk decrease (95% CI: 5%, 12%), whereas wet periods were associated with a 5% increase (95% CI: 1%, 9%), compared with periods of moderate rainfall. In models considering the interaction between extreme and antecedent rainfall conditions, wet periods were associated with a 13% risk increase (95% CI: 6%, 19%), whereas wet periods followed by extreme events were associated with an 11% increase (95% CI: 5%, 18%). Associations were substantially magnified when analyses were restricted to cases attributed to serovars commonly isolated from wildlife/environment (e.g., Javiana). For example, wet periods followed by extreme rainfall were associated with a 34% risk increase (95% CI: 20%, 49%) in environmental serovar infection. Conclusions: Given the associations of short-term extreme rainfall events and longer-term rainfall conditions on salmonellosis incidence, our findings suggest that avoiding contact with environmental reservoirs of Salmonella following heavy rainfall events, especially during the rainy season, may reduce the risk of salmonellosis. https://doi.org/10.1289/EHP4621, Introduction Every year, over 9 million cases of foodborne illness occur in the United States. Nontyphoidal Salmonella is estimated to cause 1 million of these cases (with 23,000 hospitalizations and [...]

BACKGROUND: Short-term exposure to ambient fine particulate matter ([PM.sub.2.5]) concentrations has been associated with increased mortality and morbidity. Determining which sources of [PM.sub.2.5] are most toxic can help guide targeted reduction of [PM.sub.2.5]. However, conducting multicity epidemiologic studies of sources is difficult because source-specific [PM.sub.2.5] is not directly measured, and source chemical compositions can vary between cities. OBJECTIVES: We determined how the chemical composition of primary ambient [PM.sub.2.5] sources varies across cities. We estimated associations between source-specific [PM.sub.2.5] 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 sourcespecific [PM.sub.2.5] 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 [PM.sub.2.5] and respiratory disease ED visits. RESULTS: We found that [PM.sub.2.5] from biomass burning, diesel vehicle, gasoline vehicle, and dust sources was similar in chemical composition between cities, but [PM.sub.2.5] from coal combustion and metal sources varied across cities. We found some evidence of positive associations of respiratory disease ED visits with biomass burning [PM.sub.2.5]; associations with diesel and gasoline [PM.sub.2.5] were frequently imprecise or consistent with the null. We found little evidence of associations with dust [PM.sub.2.5]. CONCLUSIONS: We introduced an approach for comparing the chemical compositions of [PM.sub.2.5] sources across cities and conducted one of the first multicity studies of source-specific [PM.sub.2.5] and ED visits. Across four U.S. cities, among the primary [PM.sub.2.5] sources assessed, biomass burning [PM.sub.2.5] was most strongly associated with respiratory health. http://dx.doi.org/ 10.1289/EHP271., Introduction Many epidemiologic studies have reported positive associations between short-term exposure to ambient fine particulate matter (PM) air pollution, PM < 2.5 µm in aerodynamic diameter ([PM.sub.2.5]), and increased mortality [...]

ABSTRACT Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high [...]

Background: Few epidemiologic studies have investigated health effects of water- soluble fractions of [PM.sub.2.5] metals, the more biologically accessible fractions of metals, in their attempt to identify health-relevant components of [...]