An ambient air monitoring survey for amphibole fibers and suspended particulate was conducted near the Reserve Mining Company taconite beneficiation process, Silver Bay, Minnesota, during the period June 17, 1977 - June 23, 1978. The objectives of the study were to establish background levels of amphibole fibers and particulate, monitor the levels of these pollutants as the beneficiation plant is brought back into production and assess the impact of the construction of the tailings basin (Milepost 7) on the populated areas. During the period of the survey, the plant was not in production from June 26, 1977- December 6, 1977 except for one day, July 31, 1977. This interim report is concerned only with the period that the plant was shut down. The background levels of particulate as measured at the six sampling stations were low in comparison to the air quality standards. It appears that the construction activity at the tailings basin has little impact on the populated areas. Levels of amphibole fibers, as determined by X-ray diffraction .analysis and electron microscopy for selected samples, were also relatively low.