Is Pulmonary Tuberculosis Contagious?

Hi good day Doctors. i have a son whose x-ray result from radiologist impression was minimal ptb but the Pulmonologist find it hard to find any trace from the result and she said that it may due to allergic rhinitis because they are closely related. we've done PPD exam and it will be check after 3 days. my concern is , is it contagious? are we in high risk of contaminating PTB? Please help me. thank you