Asthma is a heterogenic disease with different phenotypes. However, there are patients not fitting into the phenotypes and no consensus on definitions. There is a lack of studies on samples from the general population and the stability of phenotypes. As the prevalence of both asthma and obesity is rising, more patients with obese asthma is to be expected. Assessing symptoms, lung function and work ability, and examine whether there is a synergetic effect between asthma and obesity will help understanding this phenotype, ultimately resulting in better treatment of a difficult to treat group of patients with asthma. Further, we aim to assess how occupational exposure influence the different asthma phenotypes. This will generate knowledge on how to follow up exposed patients with asthma. We have collected more detailed data than previous studies on exposure and respiratory health from 16.099 inhabitants in Telemark. In 2018 all these responders and those previously not invited in the same age group (16 to 50 years) were invited, resulting in 12.930 responders. 651 asthma cases and 661 controls underwent medical examination in 2014-2015. Data collection from the follow-up of these are now in progress and 950 subjects are now examined. Working together in an extensive international network and by combining unique data from the Telemark our aim is to give a better understanding of the different asthma phenotypes, a key to better prevention and personalized treatment of asthma.