Participants in the intervention group received a structured play-based nasal hygiene education program designed for preschool children. The program included visual educational materials, an animation-based educational video, and play-based skill development activities. The intervention aimed to improve children's nasal hygiene knowledge and performance, and hand hygiene after nasal cleaning.

Participants in the control group did not receive any nasal hygiene education during the data collection period. After completion of the post-test measurements, the nasal hygiene education program was also provided to the control group.

The intervention consisted of a structured nasal hygiene education program developed for preschool children. The program included group-based education using visual educational materials, an animation-based educational video, and demonstration of nasal hygiene steps. It also included individual play-based practice stations: nasal air pressure development activities, nasal airflow performance activities, nasal hygiene sequencing cards, and a simulated nasal hygiene practice station. The program targeted both cognitive learning and psychomotor skill development.

Children's nasal hygiene knowledge was assessed using the Nasal Hygiene Knowledge Sequencing Test. The test consists of eight visual cards representing the steps of nasal hygiene. Children were asked to place the cards in the correct order. Each correctly ordered card was scored as 1 point and each incorrectly ordered card was scored as 0 points. Higher scores indicate a higher level of nasal hygiene knowledge.

Nasal air pressure performance was assessed using the Nasal Air Pressure Measurement Test. A lightweight paper strip was fixed to the child's nasal bridge, and the child was asked to blow through the nose with the mouth closed. Performance was evaluated based on the angle difference between the baseline position of the paper and the maximum elevation angle achieved during nasal blowing. Higher angle differences indicate better nasal air pressure performance.

Nasal airflow performance was assessed using the Nasal Airflow Performance Test. A lightweight pom-pom ball was placed inside a cardboard tube attached to a pediatric respiratory mask. Children were asked to blow through the nose with the mouth closed to move the pom-pom out of the tube. Performance was evaluated using two parameters: success in expelling the pom-pom from the tube and the time required to expel the pom-pom. Successful expulsion and shorter completion time indicate better nasal airflow performance.

Children's nasal hygiene skills were assessed using the Nasal Hygiene Skill Assessment Checklist. The checklist evaluates children's performance of nasal hygiene steps in a simulated environment. Each skill step was scored as "performed" = 3 points, "partially performed" = 2 points, and "not performed" = 1 point. Higher scores indicate better nasal hygiene skill performance. The performance was video-recorded and evaluated by independent observers.

Parents evaluated children's independent nasal hygiene performance using a visual analog scale. Higher scores indicate a higher level of independent nasal hygiene performance.