To investigate the relationship between petrochemical air pollution and risk of death due to bladder cancer, studies were conducted using a matched cancer case-control model based upon deaths that occurred in Taiwan from 1995 through 2005. Data on all eligible bladder cancer deaths were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of individuals who died from causes other than neoplasms or diseases associated with genitourinary problems. The controls were pair matched to the cases by gender, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each case. The proportion of a municipality's total population employed in the petrochemical industry in a municipality was used as an indicator of a resident's exposure to air emissions from the petrochemical industry. The subjects were divided into three levels (< or =25th percentile; 25th-50th percentile; >50th percentile). Subjects who lived in the group of municipalities characterized by the high levels of petrochemical air pollution had a significantly higher risk of death attributed to bladder cancer than subjects in the group that lived in municipalities with the lowest petrochemical air pollution levels, after controlling for possible confounders. The findings of this study warrant further investigation of the role of petrochemical air pollution in the etiology of bladder cancer.