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cancer risks that substantially exceed 10 per million for occupants with continuous <br />occupancy. <br />Even composite wood products manufactured with CARB certified ultra low emitting <br />formaldehyde (ULEF) resins do not insure that the indoor air will have concentrations of <br />formaldehyde the meet the OEHHA cancer risks that substantially exceed 10 per million. <br />The permissible emission rates for ULEF composite wood products are only 11-15% lower <br />than the CARB Phase 2 emission rates. Only use of composite wood products made with <br />no -added formaldehyde resins (NAF), such as resins made from soy, polyvinyl acetate, or <br />methylene diisocyanate can insure that the OEHHA cancer risk of 10 per million is met. <br />If CARB Phase 2 compliant or ULEF composite wood products are utilized in construction, <br />then the resulting indoor formaldehyde concentrations should be determined in the design <br />phase using the specific amounts of each type of composite wood product, the specific <br />formaldehyde emission rates, and the volume and outdoor air ventilation rates of the indoor <br />spaces, and all feasible mitigation measures employed to reduce this impact (e.g. use less <br />formaldehyde containing composite wood products and/or incorporate mechanical systems <br />capable of higher outdoor air ventilation rates). See the procedure described earlier (i.e. <br />Pre -Construction Building Material/Furnishing Formaldehyde Emissions Assessment) to <br />insure that the materials selected achieve acceptable cancer risks from material off gassing <br />of formaldehyde. <br />Alternatively, and perhaps a simpler approach, is to use only composite wood products (e.g. <br />hardwood plywood, medium density fiberboard, particleboard) for all interior finish <br />systems that are made with CARB approved no -added formaldehyde (NAF) resins. <br />20 of 19 <br />