A collapsed lung, also known as a pneumothorax, occurs when air escapes out of a lung and becomes trapped inside the space between the chest and lung cavities. This can be caused by air blisters in the lungs that break open, sudden air pressure changes, or trauma to the chest or ribcage.
The IRS interpreted this provision as applying only to full-time students. In a 1993 technical advice memorandum, the IRS provided a safe-harbor definition of a full-time undergraduate student as one who is taking 12 credit hours and working no more than 20 hours per week.
Full-time student. Student defined. To qualify as a student, your child must be [enrolled], during some part of each of any 5 calendar months of the year:... Most colleges consider 12 semester hours per semester to be full-time at the undergraduate level and 9 hours per semester at the graduate level.