Some flight attendants were too ill to perform their safety duties, while others have been permanently disabled. Witkowski says that the complaints of flight attendants do not always prompt correct maintenance. They are not required to put filters in. The law doesn't even require that they put filters in. Some planes don't have filters at all.
Airlines are under great pressure to get their flights out on time.
So they do not pay as much attention to systems that are not as critical to flight safety. The claim that noni is therapeutic is very dubious. More than half of the 200 subjects reported health problems they attributed to cabin air. This is based on reports from airline flight attendants and the quality of the air in the cabin. Yes, someone may have gotten sicker, but there's never any hard evidence, it seems.