Riders donned surgical face masks at the 2019 Tour de Siak race in Jakarta, Indonesia to protect their lungs from smoke.
It didn’t help.
Robert Muller (NEX CCN CYCLING TEAM) had difficulty breathing and sought medical treatment. He was immediately given oxygen by the medical team.

Muller commented that while competing in smoke he experienced shortness of breath even though wearing a surgical mask. “It’s hard to breathe, dizzy,” he said.
Dr. Dini who treated Muller said, “Earlier after we treated, conditions began to improve. He was not used to racing with the smoke condition.”

With thick smoke, haze and poor visibility from forest fires engulfing the region, organizers canceled the race after only 20km.
“Due to the condition, I have taken this decision prior to the doctor’s warning. The best step is to stop the race. When such a thing happens, it is out of our control,” said Sondi Sampurno, director of the cycling race.