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MACHADO PROPERTY Page 9 <br /> WKA No. 6078.02 <br /> November 1, 2004 <br /> The SCS indicates that the soils found in the project area have historically and predominantly <br /> supported irrigated pasture. Other irrigated crops listed as typically cultivated on soils of the <br /> project area are orchard crops. <br /> Radon Potential <br /> This discussion of the potential for radon exposure for the subject property and vicinity is based on <br /> review of available scientific literature on the topic. Radon isotope-222 is a colorless,odorless, <br /> tasteless radioactive gas that is a natural decay product of uranium. Uranium and radon are present <br /> in varying amounts in rocks and soil,and radon is present in background concentrations in the <br /> atmosphere. Current evidence indicates that increased lung cancer risk is directly related to radon- <br /> decay products. <br /> Radon potential of rocks and soils and indoor radon exposure levels in the United States are <br /> currently areas of intense research by governmental regulators as well as the geoscience and <br /> medical communities. At this time,the EPA has recommended an"action"level for indoor radon <br /> concentrations at or exceeding 4 pico-curies per liter of air(pCi/1). The EPA has extrapolated a 1% <br /> to 3%lung cancer mortality rate due to a lifetime of exposure at 4 pCi/l;that is, 1 to 3 persons per <br /> 100 exposed to this concentration for life will die of lung cancer induced by radon. <br /> The California Statewide Radon Survey Interim Results,based on the EPA/State Department of <br /> Health Services State Radon Survey,predicts that only 3.6%of homes in San Joaquin County <br /> would exceed the EPA's recommended level of 4 pCi/l. Additionally,California ranks as the third <br /> lowest for percentage of homes exceeding 4 pCi/l of the 33 states participating in the study. <br /> Specific indoor radon information for new(proposed)buildings on the subject property can only be <br /> obtained subsequent to construction of site buildings where radon testing would be feasible. EPA <br /> generically recommends that all owners test their homes and commercial buildings for radon. <br /> Site-specific geology, construction materials and methodologies,use characteristics of building <br /> occupants and the quality of construction can all affect indoor radon results. Based on the low <br /> percentage of homes predicted to exceed the EPA's recommended exposure level as described <br /> • above,the potential for radon concentrations exceeding 4 pCi/1 at the subject property is estimated <br /> to be low. <br /> NNK <br /> WALLACE-KUHL <br />