A continuous numerical scale for determining the degree of fibrosis in lung specimens was devised for correlation with other pulmonary variables such as lung function tests or mineral burden. Grading was scored on a scale from 0 to 8, using the average of microscope field scores. The system allows fibrosis to be measured in small samples of tissue (1 cm) which can provide a detailed description of the changes in a lung, currently not possible with most existing methods.