If I had copd what would my average spo2 level be? I sleep study for sleep apnea but breathing can be hard during day and wonder if causing afib

Depends. severe COPD average spO2 runs around 88-93%. Mild COPD above 95%-these are at resting or non acute states. COPD is also one of the main causes of AFibb as it places pressure on Atria-which are top chambers of heart-over time, causing them to stretch thin and then Fibrillate. Holter monitor would help see if u are having AFibb during a regular day for u. And PFT's tells where COPD is in severity.