Passenger activity at Des Moines International Airport was up 4.1 percent in March compared with a year ago, the airport announced today. A total of 195,194 passengers went through the airport in the month, up from 187,470 in March 2013. Year-to-date, passenger activity is up 2.8 percent over a year ago, as a total of 536,006 passengers have gone through the airport in the first three months. Cargo activity was down 7.3 percent for the month and 6.1 percent for the year.