Exposure to airborne particulate matter (PM) is a major risk which increases pulmonary diseases such as asthma, chronic bronchitis, or chronic obstructive pulmonary disease (COPD). PM is a complex mixture with physiochemical properties that can vary over time and space, presenting a challenge when attempting to analyze their health risks. In this study, we compared two kinds of commercial PM with real PM to explore an index which takes account of both the diverse physicochemical properties of PM and accurate prediction of their toxicities. Our results indicated that the oxidative potential (OP) of PM significantly affects their cytotoxicity. In comparison to two kinds of commercial PM such as carbon black and SRM-1648a, real ambient PM