Table 1.

Study population

	Number	Percent
Women who delivered at Kyushu University Hospital and resided in Fukuoka Prefecture	695	100
Women who resided within a 20-km radius of the Yoshizuka monitoring station (the nearest station to Kyushu University Hospital)	641	92.2
Women who resided near Yoshizuka station or one of the four other monitoring stations (as the nearest station to their respective residential postal code region) in Fukuoka city	584	84.0
Women who resided in Fukuoka city	433	62.3
Women who resided near Yoshizuka monitoring station (as the nearest station to their respective residential postal code region)	279	40.1