What is the ruling on working in the specialty of occupational medicine in a government hospital, which involves examining workers and visiting various workplaces that may be usurious companies or factories that produce unlawful things?

Medical work is permissible, and so is earning a wage for it. However, it is not permissible for a doctor to examine a person for the purpose of working in a winery or an interest-based bank, because that constitutes cooperation in sin. Nor is it permissible for him to go to places where forbidden acts are committed to certify their suitability, as that constitutes condoning evil.