The first phenomenon talks about the worsening situation of noise pollution. The average level of noise in Seoul last year was 68 decibel, well over the legal limit of 65 decibel. However, Seoul is not the only noisy city in Korea, where among 33 cities, 13 exceeds the regulations. Among 2,086 environment-related petitions submitted to the National Environmental Dispute Resolution Commission since 1991, 86 percent or 1,790 cases were noise and vibration related. Also, survey done by the National Statistical Office of people aged 15 or more last year, 92.8 percent said noise got worse in recent years. Furthermore, they claimed that repeated exposure to noise over 85 decibel for eight hours or more a day can increase mental stress and damage hearing.