Shops are closed in Monrovia's West Point neighborhood as part of a quarantine to contain the spread of Ebola. Zoom Dosso/AFP/Getty Images hide caption

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A health worker cleans his hands with chlorinated water before entering an Ebola screening tent at the Kenema Government Hospital in Sierra Leone. More than 300 Sierra Leoneans have died of the disease. Michael Duff/AP hide caption

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Princeton University's Nassau Hall. DANIEL HULSHIZER/AP hide caption

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Industrial cities like Detroit have high levels of lead in the aging housing stock and in soils. Researchers found that the amount of soil lead in Detroit that gets suspended in the air correlated with the levels of lead in kids' blood. Spencer Platt/Getty Images hide caption

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A woman uses a cellphone while driving in Los Angeles in 2011. Damian Dovarganes/AP hide caption

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As an armchair disease detective, you don't have to bother with mundane tasks, like culturing fluorescent bacteria or interviewing the ill. Centers for Disease Control and Prevention hide caption

itoggle caption Centers for Disease Control and Prevention