COPD

I recently cared for a resident who had COPD. The family had just taken him outside to smoke and was concerned that he was not breathing well when he came back to the floor. His SPO2 on room air was 84 to 89. He was not hypoxic , nor was he in any acute visual distress. He was alert and oriented and made no effort to complain. When asked if he was ok he just said I wanna smoke. His radial pulse was 98. I previously checked the resident (1 hour prior) per family request and his spo2 on room air was 92-94 his pulse was 88 and his B/p was 110/60. When you have a COPD patient in no visual distress I was taught that an SPO2 saturation of 88% to 92% was a normal range was this information incorrect? The facility I worked in before we always maintained our residents with COPD between 88-92 with or without oxygen , if they stayed below 88 for extended time oxygen therapy was applied at 2 L/M via nc and the order was to maintain them between 88-92 to prevent them from becoming hypercapnia. Any information on this would be great