"Hi to all, I was diagnosed with COPD a year and eight months ago. To prevent things from getting worse I use my treadmill every day. I walk 2 and 1/3 miles at 2.9 MPH and a 3.5% grade. During my walk I check my oxygen levels with an oximeter. The other day I was shocked to see my reading was 69. I have never seen it that low. I did not feel any different than normal so I went ahead with my walk. As I walked I kept checking and the numbers came up to 70, then 84 and finally 94. My questions are: how could the reading be so low and I still felt fine? A PT told me at 75 I should use my rescue inhaler (I have never used it because I never felt the need). Also, why would the numbers go up as I exerted myself. Logic would tell you that it would go down. Overall, I am glad that I am doing well and I do give credit to my daily routine of walking. I am 75 years old and quit smoking in June of 1990. Any thoughts? "