“His curiosity comes from working as a wax technician for Canadian elite cross-country skiers in the early- to mid-2000s while he was still getting his PhD. He travelled with teams for months and noticed how breathing issues would worsen as the ski season wore on. ‘By the time you got to national or the spring season races in March, they were hacking all the time, so they basically had chronic cough,’ he said. ‘It’s not healthy to have chronic cough.'” CBC News: Why winter exercise can be especially hard on the lungs.