About 37 percent of homes built four to five years ago have a higher concentration of a chemical that apparently causes the so-called sick building syndrome, according to the results of a study conducted by the Infrastructure Ministry.
Formaldehyde has been blamed for inducing headaches, dizziness and nausea in occupants of houses inflicted with the syndrome. The limit on formaldehyde concentration stipulated by the Health, Labor and Welfare Ministry is 0.08 parts per million.
According to the survey conducted by the Land, Infrastructure and Transport Ministry, 36.7 percent of houses built four to five years ago exceed the Health Ministry's limit on the chemical. On average, 27.3 percent of houses exceed the ministry limit, while 28.8 percent of homes built within the past year and 28.9 percent of houses built in the past two to three years also surpass the figure, the survey shows.