The researchers of the CERH have a broad national and international collaboration network with organizations of a different kind. CERH is co-operating widely with the universities, research institutes, ministries, municipalities and other organizations in the field of environment and health. The researchers of the CERH have also collaborated with WHO and its Regional Office for Europe during the last decades. This long term co-operation has resulted in a request from WHO to apply for designation as a collaborating center on “Global change, environment and public health”.