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.
Here are the IRS definitions for at least a 1/2 time student, quoted from form 1098-T instructions . Box 8. Check if at Least Half-Time Student. Check this box if the student was at least a half-time student during any academic period that began in 2011. A half-time student is a student enrolled for at least half the full-time academic workload for the course of study the student is pursuing.