The Material Damage Review Subcommittee of the EPA Clean Air Scientific Advisory Committee identified in a report of the impact of acid deposition on building materials, omissions, errors, and biases inherent in the work, and attempts to account for a range of possible alternatives by furnishing lower and upper damage estimates. In view of the uncertainties involved, especially in paint damage costs, the Subcommittee believes that the total costs from acid deposition should not be used in the Sulfur Oxides National Ambient Air Quality Standards (NAAQS) rulemaking process. Nevertheless, the conceptual framework and procedures that are used in the report do provide useful information which should be considered.