The association between air pollution level and breast cancer risk in Taiwan.

Breast cancer has the highest incidence of cancer among women in Taiwan, and air pollutants have been documented to have multiple adverse effects on human health. There is no relevant data, there has been no research in Taiwan to discuss the relevance of air pollutants to breast cancer, and evidence is sparse and inconclusive.Air quality data used in this study was collected from the 78 air quality monitoring stations situated in 74 municipalities in Taiwan during 2000 to 2011. The daily measurements taken at each monitoring station represented the level of exposure for each participant residing in that zone. The air pollution concentration is partitioned based on the concentration level in Quartile. We calculate the annual average air pollutants concentration (CO, NO, NO2, PM2.5, THC, and CH4) and the long-term average exposure levels of these pollutants until diagnosis of breast cancer, ending the study period for each individual.Patients who were living in areas with the highest air pollutants concentration (Quartile 4) had the most people diagnosed with breast cancer (CO:1.47%, NO:1.41%, NO2:1.63%, PM2.5:0.91%, THC:1.53%, CH4:2.33%). The patients who were exposed to Quartile 1 level of CO, NO, and NO2 concentration were the oldest, and other patients who were exposed to Quartile 4 level of CO, NO, and NO2 concentration were living in the areas of highest urbanization. Participants exposed to Quartile 4 level concentrations of air pollutants were associated with highest hazards ratios for breast cancer incidences.Most participants who were exposed to the high concentration of air pollutants (CO, THC and CH4) had a significantly higher risk of breast cancer. If we can improve air pollution in the environment, we can reduce the incidence of breast cancer and save precious medical resources.