Is the pneumonectomy a risky thing to do?

Benefit vs risk. A pneumonectomy is a major surgery in which an entire lung is removed. Like any major surgery, there can be complications - some serious. Risks include bleeding, infection, irregular heartbeat, blood clots after surgery, & even a heart attack. However, if you have a serious illness like lung cancer, the benefit to surgery may outweigh the risks. I urge you to discuss concerns w/ your doctor.
Can be. Surgeons try to avoid pneumonectomy by performing lung sparing surgery called sleeve lobectomies.