/ Source resolution and risk apportionment of emission source categories for risk reduction purposes can be used to enhance the Bubble Policy of the Clean Air Act, This is performed by incorporating receptor modeling techniques of factor analysis and chemical mass balances to assess noncarcinogenic and carcinogenic inhalation risks to a target population for certain pollutants coming from major emission source categories in a steel plant air shed. Source resolution, using factor analysis, statistically interprets a "source" from ambient data. By subsequently quantifying risks from identified metal emission sources using chemical mass balances and risk apportionment, a total additive risk from main source contributors in the steel plant is estimated. From this methodology, the Bubble Policy can be enhanced by targeting only main risk sources or by "risk-trading" with minor impact sources to reduce the total risk (if deemed significant) without arbitrarily reducing risk for all sources in an industrial source complex's "bubble."Particulate matter in ambient air poses major health consequences in industrialized air sheds. Epidemiologic observations have indicated a possible correlation between exposure to large doses of particulate matter and an increased incidence of lung cancer for target populations in the proximity of steel foundries. Particulates emitted from steel foundries, such as ferric oxide, chrome, and nickel, have been found to be associated with the incidence of lung cancer in industrial settings (Lloyd 1978). Thus, emissions of particulate pollutants from industrial sources is a point of public health concern as to whether their presence in the ambient environment has any significant impact in the current trend of increased cancer incidence in the general population.Currently, risk estimates are based on calculations done for single emission sources or with monitored data of ambient air pollutants. Air waste management plans that use risk assessment attempt to identify exposure and health impacts from emission sources based on emission profiles and inventories applied to