A series of ice nucleus measurements at Mauna Loa Observatory obtained concurrently with Millipore filter samples which were subjected to chemical analyses for chloride particles are briefly described. These aerosol concentrations displayed a pronounced relationship with flow regimes at the Observatory. The results emphasize the need for care in collecting data at this unique site to insure against contamination from low-level sources. Both aerosols increased up to nearly three orders of magnitude during sustained diurnal upslope flow conditions. The depiction of chloride particle counts with distance from the shoreline of the Island of Hawaii was in general agreement with similar data obtained in the Puerto Rican environment.