The aim of this study is to explore whether lung cancer associated with air pollution has cell type specificity. The air quality data (SO(2), CO, O(3), NOx) from the Taiwan EPA's air quality monitoring stations were collected between 1995 and 1998. Patients with lung cancer were identified through the National Cancer Registration Program operated by the Taiwanese government. Two major pathological types (adenocarcinoma (AC) and squamous cell carcinoma (SCC)) were considered. The Pearson correlation coefficients between the air quality index and age-standardized incidence rate per 100,000 person years (ASR) of AC and SCC were calculated for both genders for three township categories characterized by different levels of air pollution. The traffic-related NOx and CO showed significant correlations with female lung cancer incidence rate, with Pearson's correlation 0.33 (P=0.03) and 0.40 (P=0.01) respectively. However, the correlation between air pollution and lung cancer was not significant for males. Significant correlation coefficients were also found between the ratio of AC/SCC and the mean concentrations of NOx (r=0.41, P=0.04) and CO (r=0.47, P=0.02) in females. Our results show that the worse the air pollution was in the area, the higher the AC rate, regardless of gender. On the other hand, SCC incidence rates did not increase with increasing air pollution. Our results show that a correlation exists between air pollution and lung adenocarcinoma incidence.