If FEV1 is 1.3 L, FVC is 3.1 L in an adult man, the pattern is suggestive of:

Obstructive lung disease:- - FEV1 is reduced due to obstruction of air escaping from the lungs. Thus, FEV1/ FVC ratio will be reduced. Restrictive lung disease:- - FEV1 and FVC are equally reduced due to fibrosis or other lung pathology . Thus,FEV1/FVC ratio -normal or even increased. In this question, a ratio of 1.3/3.1 is about 40% in contrast to a normal of > 80%.