There are many causes for this condition:

Common cold, inflammation of the nose or sinuses, hay fever, deviated septum (when the partition between your nose is crooked), and nasal polyps( tumors) can cause swelling of the nasal and sinus passages and lead to sinusitis. Smoking or breathing in smoke interferes with the function of sinus leading to infection. Using decongestant nasal sprays too much, smoking, and swimming or diving can also increase our risk of getting sinusitis. Some people have growths called polyps that block their sinus passages. Very young children may be prone to developing sinusitis because their smaller sinus passages become obstructed more easily than those of adults. Damp weather, especially in northern temperate climates, or pollutants in the air and in buildings also can trigger sinusitis. Sinusitis occurs more often in people who have reduced immune function such as AIDS. Drinking alcohol also causes nasal and sinus membranes to swell. If you have asthma, an allergic disease, you may have frequent episodes of chronic sinusitis.