If 30% lungs are working and 70% ve been damged ... it could be recovered.....? is it dangerous ? if yes then how much ?

To complex: It sounds like pulmonary function test show 30% of normal lung function. It is an oversimplification to say that 70% of your long is not working well 30% is. More importantly, the answer to your question would be easier to address if you were sitting in the office and we could get the rest of your medical history. The cause of loss of lung function is at least as important as the degree of loss.