An evaluation of asbestos (1332214) exposure during low income housing weatherization was performed by NIOSH following a request by the Denver, Colorado, Regional Office, Department of Energy after a local company that weatherized low income houses was cited by OSHA for not having a historic database on asbestos and for having its employees potentially exposed during weatherization, especially as a result of using the blower door technique for determining leakage of outside air into the homes. The evaluation consisted of determining which homes contained asbestos, performing air monitoring for asbestos during all phases of weatherization in asbestos containing homes, analyzing bulk samples for asbestos, determining total dust concentrations, and observing work practices. Nine houses suspected by the company of containing asbestos were found to contain chrysotile (12001295). The concentrations ranged from 5% in the siding to 40 to 70% in the duct wrapping material. Air samples contained fiber concentrations up to 1.8 fibers per cubic centimeter (f/cc). The samples contained little or no asbestos. The maximum asbestos concentration was 0.02f/cc. Total dust concentrations occurring while blowing in cellulose insulation ranged from 2.2 to 41mg/m3. The highest concentrations occurred while blowing in insulation in the attics. Workers who installed insulation in the attics complained of eye irritation. The blower door technique did not increase the concentration of airborne asbestos or cause any settled asbestos to become airborne. The authors conclude that the company can successfully identify asbestos containing materials. The authors recommend that home weatherization companies provide their employees with training on asbestos identification and hazards and require attic insulation workers to use eye as well as respiratory protection.