Radon in Japan
Official radon data, regulations and resources
What should you do?
Regardless of the official classification, the only way to know the radon level in a specific building is to measure it. A long-term test (at least 3 months) is recommended. You can either test yourself with passive detectors or hire a certified professional.
Regulations & obligations
Dwellings
Japan has not set a national reference level for radon in dwellings. The nationwide survey of 2007-2010 (3,900 homes) measured an average of 14.3 Bq/m³ and estimated that 0.1% of dwellings exceed 100 Bq/m³.
Professional services
Radon Measurement Service Providers
Environmental health companies offering radon testing under general business licenses
Environmental Analysis Laboratories
JNLA or JCSS-accredited laboratories for environmental radiation analysis including radon
Accredited by: JNLA/JCSS
Workplace Health & Safety Consultants
Occupational health consultants addressing radon in workplace settings under MHLW guidelines
How to test for radon yourself
Regardless of where you live, testing for radon is easy and affordable. A long-term measurement with passive detectors is the most reliable way to know your indoor radon level.
Learn how to testMajor Cities
Tokyo
9,733,276 inhabitants
Yokohama
3,777,491 inhabitants
Osaka
2,753,862 inhabitants
Nagoya
2,332,176 inhabitants
Sapporo
1,973,832 inhabitants
Fukuoka
1,612,392 inhabitants
Kawasaki
1,538,262 inhabitants
Kobe
1,525,152 inhabitants
Kyoto
1,463,723 inhabitants
Saitama
1,324,854 inhabitants
Hiroshima
1,200,754 inhabitants
Sendai
1,096,704 inhabitants
Chiba
979,768 inhabitants
Kitakyushu
940,978 inhabitants
Sakai
826,161 inhabitants
Niigata
797,591 inhabitants
Hamamatsu
791,707 inhabitants
Ōta
748,081 inhabitants
Kumamoto
738,907 inhabitantsHigh (geology estimate)
Aihara
725,493 inhabitants