Exposure assessment was performed during the abatement of amosite containing material (ACM) and chrysotile containing material (CCM). Mean fibre concentrations (MFC) in breathing zone (BZ) were 20.6+/-7.9 f/cc and 6.3+/-2.2 f/cc during abatements of ACM and CCM, respectively. At the fixed station, MFC were 5.4+/-3.5 f/cc for ACM and 2.9 f/cc+/-1.6 for CCM. For observer's BZ, MFC were 3.1+/-1.3 f/cc (ACM) and 1.8 f/cc (CCM) during the abatement. Though elevated, area and observer-type samples clearly underestimate exposure. Exposure remained unacceptable in the worksite with the class of respiratory protection used.