sentences:  Questions were raised about detrimental health effects after experiments in San Francisco, California, were followed by a spike in hospital visits; however, in 1977 the Centers for Disease Control and Prevention determined that there was no association between the testing and the occurrence of pneumonia or influenza.The San Francisco test involved a U.S. Navy ship that sprayed "Serratia marcescens" from the bay; it traveled more than 30 miles.One dispersion test involved laboratory personnel disguised as passengers spraying harmless bacteria in Washington National Airport.