A total of 53 students participated in the study, of whom 31 (58.5%) were male and 22 (41.5%) were female. The average age of the participants was 7.3 years old. One par-ticipant dropped out during the dry season, which did not affect the study since the sample size was still large enough based on the detectable differences of the sample size, using
the standard power cutoff of 90%. All participants from the rice farming area were from rice farming families whose houses were located less than 500 meters from the rice paddy fields. In contrast, participants from the aquacultural farming areas were not from rice farming families, and their houses were not adjacent to any rice paddy fields. The environmental conditions and activities of participants are presented in Table 1. Most of the farmers in the rice area indicated that they used PYR in their farms, while none of the farmers in the aquaculture area used PYR for any agri-cultural purposes. PYR products, whether they be in spray, coil, or electric form, were commonly used for household purposes in both study areas. The frequency of PYR use in households was significantly higher during the dry season in both study areas (χ2 test, P,0.05). However, they were significantly less frequently used for floor-cleaning using wet mops during the dry season in both study areas (χ2 test,
P,0.05). Participants coming from the rice area reported that they played more frequently in rice farms compared with those from the aquacultural area, during the wet and dry seasons. The personal hygiene of the participants, which included observable dirt on the body and the washing of