Chemotoxic and Asphyxiation Assessment

NNL has a deep, comprehensive understanding of safety case needs, right across the nuclear industry. Meaning we have the expertise to deliver a complete suite of nuclear safety assessments, from specific safety assessments to the management of full safety cases.


Chemotoxic assessments aim to examine the risks to human health posed by the release of a hazardous substance. The focus is on the sudden accidental release of a substance and the risk of an acute exposure.

This is in contrast to routine or low level emissions of a substance, dealt with elsewhere - for example in COSHH assessments.  With a fully developed toolbox of chemotoxic technical guides and methodologies, we have a track record of meeting regulatory requirements.

Working across a diverse range of facilities such as chemical plants and reprocessing facilities, it's easy to see why we're a market leader in specialist chemotoxic assessments.


When an asphyxiation hazard is identified, an Asphyxiation Assessment is a vital part of any safety case. NNL has a wealth of experience in this crucial area. Such tests look at the risks to human health posed by the release of asphyxiating substances. One of our most recent innovations is the development of an asphyxiation area classification scheme. In fact, it's proved extremely useful in the design of a retrievals facility at Sellafield. Here, there is a constant need to balance different relative risks, from both a radiological and asphyxiation perspective.


COMAH assessments look at the Control of Major Accident Hazards Regulations. Carrying out COMAH assessments in the form of COMAH Safety Reports for the Springfields Site, our experience is far-reaching.

Our COMAH Safety Reports have demonstrated that operations and activities involving or generating COMAH substances can be safely managed and the risk of a major accident as low as reasonably practicable.