Only 23 percent of some 103,000 homes in seven prefectures had been fully decontaminated as of the end of December under a nuclear disaster government program, the Environment Ministry reported.
The percentage was virtually unchanged from the previous survey conducted at the end of August due to a rise in the number of dwellings covered by the decontamination program as well as difficulties in obtaining consent from homeowners, the ministry said Friday.
By contrast, decontamination work had been completed for 85 percent of schools and preschool facilities by the end of 2012.
The figures covered areas in 58 municipalities in Iwate, Miyagi, Ibaraki, Tochigi, Gunma, Saitama and Chiba prefectures. Fukushima Prefecture was excluded from the survey.