Sinusitis occurs when the air filled cavities inside the skull become inflamed. Certain factors increase the risk of developing sinusitis. For example,
Having hay fever or running nose.
Being in Day care
Having a condition that affects the cills.
Undergoing altitude changes, such as those that occur during air travel or scuba diving.
Having enlarged adenoids or rarely an infected tooth.
Having an immune system that's compromised by chemotherapy, HIV infection.
Having cystic fibrosis, an inherited disease that results in thick sticky mucus in the lungs and digestive track.
Courtesy : The Hindu, Wellness, 21/2/12.