Low Oxygen level. A lot. please advise.

Hi Doctors, I'm 37 years old male. I was randomly checking my oxygen level with oxymeter at my friends house and I could see my oxygen is 94,93 and if I breath deeply it will go to 98 , 97 but when I breath slowly it will go back to 95,94 or 93. I verified this from past 3 days.  I dont have have shortness of breath or other issues . I dont smoke cigarette but I get dry cough and if I go outside but once back home I won't get cough . Only during outdoor if the roads are polluted. This is happening from almost 4 years. I showed to GP long back and he advise to keep mask aways when I go back. Now after seeing the low oxygen level I'm worried a lot... please advise .. thank you.