Hi thanks for contacting HCM... Your father having interstitial fibrosis like condition that is restrictive lung disease .... It could be induced by smoking or secondary to viral interstitial pneumonia ... Spirometry done for grading severity of restrictive disease and accordingly management . You might need bronchodilator drug or steroid .... Avoid exposure to dust , pollution or smoking limited .... If needed and x ray seems suspicious biopsy can be taken for histopathological examination.... Hope your concern solved .. Consult pulmonologist for this ... Take care ...