A number of concerns and controversies surfaced before, during, and after the 2008 Summer Olympics, and which received major media coverage. Leading up to the Olympics, there were concerns about human rights in China, such that many high-profile individuals, such as politicians and celebrities, announced intentions to boycott the games to protest China's role in the Darfur conflict, and Myanmar, its stance towards Tibet, or other aspects of its human rights record. During the games in Beijing, the city was also under a high alert because of security concerns following civil unrest in Tibet and terrorist attacks by Xinjiang separatists. The levels of air pollution in Beijing also came under much scrutiny, due both to concerns about athletes' health and concerns that Beijing had failed to live up to promises it made during its Olympic bid. Foreign journalists at the games reportedly faced various restrictions to their work, limitations to internet access, and threats of physical violence. The gymnastics competition caused a major worldwide controversy during and after the games when some Chinese gymnasts were accused of being under the minimum age, but then cleared after an investigation. Other controversies surrounding the 2008 Summer Olympics included ticketing problems, displacement of Beijing residents due to construction and demolitions, and alleged persecution of individuals applying to protest.