The duration size of air pollution events refers to a state in which air pollution indices reflect unhealthy conditions over an extended period of time. Thus, a large duration size implies prolonged air pollution events. Such events exert negative effects on human health, disrupt economic activities, and deteriorate environmental ecosystems. This study proposed the use of power-law models as a tool for evaluating the behaviors of duration size for extreme and unhealthy air pollution events. Four different power-law models were used to analyze the air pollution data in Klang, Malaysia.