Concentrations of elements, including S, Al, Si, K, Ca, Ti, and Fe, in aerosols sampled sequentially with 3.7-hour time resolution over a 2-week period in April and May 1979 at the Mauna Loa Observatory, Hawaii, indicate that long-range transported 'background' crustal dust aerosol can reach concentrations in excess of 20 μg m-3 with more than 8μg m-3 of additional sulfate. Favorable regional meteorology after known dust storm episodes, as well as similarities in crustal element ratios, point to dry areas of northern China as the major source region for this crustal aerosol. Time series analysis for crustal elements show a dominant 21-hour but no 24-hour period, a result that can be accounted for by a diurnally varying source process with subsequent modification of periodicity, e.g., by wing seed convergence during transport. Time-dependent associations between S and the crustal elements, especially high coherency at long periodicities, also imply a long-range transport for much of the S, possibly from populated areas in eastern Asia, including China and Japan. This source may contribute much of the sulfuric acid believed to cause the relatively high acidity of rainwater observed at higher altitudes in Hawaii. Mauna Loa Observatory, at 3400 m altitude, is apparently an excellent location for detecting Asian dust and pollutant transport during spring with little interference from Hawaii-derived aerosol.