On September 26 and 27, 1950, the U.S. Navy conducted a secret experiment named "Operation Sea-Spray" in which some S. marcescens was released by bursting balloons of it over urban areas of the San Francisco Bay Area in California. Although the Navy later claimed the bacteria were harmless,[citation needed] beginning on September 29, 11 patients at a local hospital developed very rare, serious urinary tract infections, and one of these individuals, Edward J. Nevin, died. Cases of pneumonia in San Francisco also increased after S. marcescens was released.