Dr Christopher Mason, a geneticist at Weill Cornell Medical College, led a team that, for 18 months, swabbed the New York City subway system for the microscopic life forms that cover its turnstiles, seats, ticket booths and stations.

Dr Christopher Mason, a geneticist at Weill Cornell Medical College, led a team that, for 18 months, tested the New York City subway system for the microscopic life forms that cover its turnstiles, seats, ticket booths and stations.
