Bread mold can contain any number of fungal species, and different types can pose different risks to someone who ingests them. If you start developing any concerning symptoms such as severe nausea, vomiting, difficulty breathing, wheezing, hives
, or coughing up blood, call your doctor
Because there are many types of different fungi that can grow on bread, it is difficult to tell which type was growing on your hot dog bun. Rest assured, most types are completely harmless, and you can eat them without incurring any negative effects. This is true for the vast majority of molds. However, some are toxic and can cause food poisoning and result in nausea, vomiting, and diarrhea
. The most dangerous situation is when someone is allergic to the particular type of mold, and danger signs of an allergic reaction include symptoms such as wheezing, hives, swelling, or difficulty breathing. Because you did not actually ingest the mold, it is highly unlikely that you will experience any of these effects. If you are very allergic to the particular type of mold, you should expect to experience symptoms quite soon after breathing in the spores. Also, our noses have protective hairs called nares that block many things we breath in from getting into our system, and that can often include fungal spores from bread mold.
I would not worry too much about potentially breathing in the bread mold spores. However, if you experience any of the symptoms mentioned above, I would recommend calling your doctor immediately, and if you cannot get in touch with him or her, going to the emergency room.