Final answer:
Overexposure to R-12, also known as dichlorodifluoromethane, can result in breathing problems such as shortness of breath, cough, and headache. It can also cause the formation of aspergillomas, leading to severe complications. In extreme cases, it can be fatal.
Step-by-step explanation:
Over exposure to R-12, also known as dichlorodifluoromethane, can have several breathing problems. Inhalation of R-12 can lead to symptoms such as shortness of breath, wheezing, coughing, runny nose, and headaches. It can also cause the formation of aspergillomas, which are fungal masses that can lead to severe pneumonia and pulmonary or brain hemorrhages. In some cases, overexposure to R-12 can be fatal.