Participants run at the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. This annual running event which requires participants to run half-naked, was organized to promote environmentally friendly lifestyles. (Photo by Kim Kyung-Hoon/Reuters)





A participant wearing a facial mask runs in the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





Participants run at the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





A woman wearing a wedding dress runs at the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





A woman takes a selfie after running in the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





Participants wearing swimsuits share a light moment before running in the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





A participant blows a horn while running in the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





A participant gestures while running in the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





A boy runs at the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)





Participants run at the “Half-Naked Marathon” at Olympic Forest park in Beijing, China, February 28, 2016. (Photo by Kim Kyung-Hoon/Reuters)