Introduction Existing cohort studies in Europe capturing some type of occupational information enrol tens of millions of persons. There are few large-scale analyses systematically combining cohorts from this extraordinary resource, and a systematic approach to facilitate the use of cohorts across research groups and countries is needed.

Objectives As part of the ongoing OMEGA-NET COST Action, we created an online inventory of cohorts (https://occupationalcohorts.net/) with occupational information in Europe and worldwide and implemented an interactive search tool with detailed information on these cohorts. The inventory aims to collect information that facilitates collaboration across cohorts to explore occupation, work related exposures and health relationships.

Methods The inventory includes prospective or retrospective cohorts, case-control studies nested within cohorts and intervention studies that: (i) are active or can substantiate that their data are potentially accessible; (ii) collect data on occupation and/or industry or at least one occupational exposure; and (iii) have at least one follow-up either already conducted or planned. The inventory only incorporates cohort meta-data. Researchers enter information regarding their cohort using a web-based OMEGA-NET inventory questionnaire. The published version of the inventory is stored in a searchable web database.

Results To-date the inventory includes information on > 130 cohorts in more than 20 countries. Information is collected on: (i) Identification and basic description; (ii) Follow-up; (iii) Occupational exposures (dusts and fibres, solvents, pesticides, metals and metal oxides, other chemicals, engineered nanoparticles, biological factors, physical agents, ergonomics, physical workload and injury, psychosocial domains, organisation of work and working time); (iv) Outcomes evaluated; (v) Biological samples and analysis; (vi) Other information e.g. sociodemographic.

Conclusion The OMEGA-NET inventory will continue to identify and invite cohorts and seeks to capture the majority of available active cohorts with information on occupational exposures, many of them being non-occupational in their primary aim.