MBTA Security Goes Up Again

Just one day after the second wave of transit attacks in London, there are new developments this morning. Police have surrounded a mosque in the British capital, as well as shot and killed a man at one of the city's subway stations.

Meanwhile, here in Boston, the Massachusetts Bay Transportation Authority is again beefing up security, adding police officers and sniffing dogs on trains. To discuss mass transit security this morning, we're joined by David Ropeik, who teaches "risk communication" at Harvard University's School of Public Health.