Characterizing potential risk triggered by road traffic noise in comparison with typical air pollutants NO₂ and PM_2.5

Characterizing multiple risk stemming from automobiles are required from the viewpoint of priority setting for future risk management. However, little is known about such issues given the inadequacy of indicators. In this research, with the illustration of the metropolitan city of Osaka, Japan, using disability-adjusted life years (DALYs), impacts of road traffic noise and exhausts gas (nitrogen dioxide (NO₂) and particulate matter (PM_2.5)) were quantified and compared with the risks of ischemic heart disease and high sleep disturbance; and respiratory disease as endpoints, respectively. Health risks due to automobile noise were 3102.1 and 97.8 DALYs under the condition of open and closed windows, respectively. The health risks were reduced by 96.8% under closed-window condition. On the other hand, the health risks caused by NO₂ and PM_2.5 from automobiles were 137.6 DALYs, which was lower than the health risks due to automobile noise. These results indicate the effectiveness of DALYs as an indicator to characterize different kinds of burden of health and environmental impacts from automobiles, and they were successfully used to evaluate the effectiveness of risk reduction options such as the difference between open and closed windows. Furthermore, most people were found to have been exposed to 55-60 dB noise level. Although they easily get used to and can tolerate this level, it is also the stage at which health risks begin to occur. Therefore, with continuous exposure, qualitative estimation showed that open windows under this noise level subsequently leads to high potential health risks.