Control of Hazardous Substances W505

The course aims to describe how exposure to hazardous substances arises in the workplace and to introduce the methodologies and technologies available to control exposures and thereby reduce risks to health.

Who is it for?

This course is suitable for technicians and technologists who carry out measurements and testing in workplaces. 

How is it delivered? 

This course typically runs as a five-day taught course (minimum 45 hours, including practical/demonstration sessions, lectures, tutorials, guided reading, overnight questions and examination). 

Learning objectives

On successful completion of this module, you will be able to: 

  • Describe how airborne contaminants are generated by industrial processes, how this impacts on the control strategy, and how control solutions can thereby be optimised 
  • Recognise the range of approaches to risk reduction embodied in the hierarchy of control and select appropriate strategies for implementation 
  • Describe the meaning of "adequate control", mainly concerning personal exposures;
  • Discuss the importance of design considerations in terms of the workplace, process, and plant, as a means of reducing occupational exposures 
  • Describe the principal elements of a local exhaust ventilation system, give examples of typical installations and know-how to carry out the necessary measurements to assess whether a local exhaust ventilation system is effective and operating to the design specification 
  • Recognise the limitations of local exhaust hoods and enclosures and the means to optimise their effectiveness 
  • Describe how personal protective equipment programmes may be used in an effective manner 
  • Recognise the impact that control measures may have on other workplace hazards and understand the need to take a holistic approach to the design of control solutions 


There will be a 40 short answer question “open book” examination with an allowed time of 120 minutes.

BOHS is the only awarding body for the W500 series occupational hygiene modules as part of the OHTA International Training Scheme and Qualifications Framework.


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