Long bus trip plus BC are both risk factors for PE. Lack of trouble breathing - who knows what that means. While I did have trouble breathing, it was ONLY at the very high end output levels - fast climbing on a bike, for example. In everyday life, hiking, walking, climbing stairs, carrying groceries, riding my bike on flat or rolling terrain, I had NO trouble breathing at all. I also had a 100% oxygen sat level. And I had multiple, relatively large, PEs in both lungs.

Knowing what I know now, I wouldn't take the risk.