I was just able to finish a Pulmonary Function Test (took two tries and a very patient technician) and came back with low DCLO . A low DLCO (diffusing capacity of the lungs for carbon monoxide) can be associated with inflammation, particularly in conditions affecting the pulmonary vasculature or the alveoli. Inflammation can impair the lungs' ability to transfer oxygen to the bloodstream, leading to a reduced DLCO. Since Long COVID can significantly impact the pulmonary vasculature, I believe this is why I am so tired and can become short of breath. Now back to the doctor to see if there is anything I can do to treat it!