text: Moreover, there are difficulties to apply the same level of protection to types of work with weakened or 
  non-existing employer–worker relations, for example, temporary and subcontracted work, involuntary 
  self-employed, seasonal work, platform work, domestic work and all types of irregular work. These forms 
  of work often have as one major characteristic a**less clear employer–worker relationship**, while the 
  main structural element of the EU OSH legislation is the dual role of employers and workers in OSH. 
  
  **OSH infrastructures**
  
  There exists a**diverse and rich OSH infrastructure**in most EU Member States, that is, labour 
  inspection and other supervising authorities, governmental OSH institutes, prevention and research 
  centres, knowledge centres, OSH training and education centres, and occupational health clinics. The 
  social partners and professional organisations often contribute to this infrastructure, either in an advisory 
  way or even as an integral part of such institutions. These institutions are responsible for supervision 
  and control of compliance, they train OSH practitioners, produce guidance material, engage in 
  improvement actions and projects, and contribute to more awareness and better knowledge. In many 
  cases they help in adapting general legislation to sector- or workplace-specific regulations. 
  
  EU Member States apply very diverse regulations regarding the**number and required qualification**
  **of OSH staff in enterprises, and for external protective and preventive services**(PPS). In diverse 
  ways, the Member States prescribe topics like necessary qualifications and certificates, depending on 
  sector and work tasks, time granted for preventive work and training, and obligatory or voluntary use of 
  external PPS by enterprises, while some of these PPS offer technical support and others also medical 
  monitoring and advice. In some countries such support is granted for free in certain sectors or for certain 
  types of enterprises. The role and power of all actors in these systems varies substantially, defining 
  such roles specifically for employers, workers’ representatives and safety representatives. 