Breathing test shows spirometry is normal, lung volumes are within normal range. Severe decrease in diffusing capacity. I am not a smoker, nor been around smokers. I have shortness of breath and use an inhaler albuterol aerosol 90mcg 3-4 times per day. I take a thyrod pill, blood pressure meds. This meds keeps bp in check. I am 76 years old, self sufficient, drive, etc. overall good health for my age. I need an understanding of this diffusing process with oxygen in lungs entering the blood. Why the shortness of breath?? Need answers. Thank You Doctor for your response.