Is it ok for me to use the steam room at the gym after having pneumothorax surgery?

More needed: Details will be needed for a meaningful answer, such as reason for pneumothorax, if known, time from surgery, any preexisting conditions. Your best reference would be your treating physician, either GP or pulmonologist.

Avoid exposure.: If your need for the thorax surgery was due to medical origin, I would avoid the breathing in such an enclosed environment. Your physician should be consulted.