Knowledge of nasal wash before and after intervention (n=80) The steps Before1 After 3-month intervention After 6-month intervention 2 p1&2 n% n% n% Complete 4 steps 1 1, 25 4 5, 0 49 61, 2 <0, 001 * After work having nasal wash 30 37, 5 61 76, 3 78 97, 5 <0, 001 *) Fisher's Exact Test Comment: Before intervention, 1.25% of subjects have proper knowledge of nasal wash, after 6 months, this rate is 61.2%.