In addition to affecting air quality and natural environmental degradation, transportation can also play a key role in the degradation of urban environments. The delays and frustrations caused by urban traffic congestion can reduce human productivity and quality of life, thus possibly reducing the potential gross domestic or gross regional product. The noise produced by various types of motor vehicles, as well as the excessive use of horns–a fact of life in cities in many developing countries–raises the level of ambient noise, increases stress and reduces the quality of life. Transportation can also contribute to the.
