Which of the following substances is specifically mentioned as not covered by COSHH?

The correct answer is pinpointed because COSHH, the Control of Substances Hazardous to Health Regulations, pertains to substances that could potentially pose a risk to health when they are used at work. Asbestos is explicitly mentioned in health and safety legislation as a substance that has its own specific regulations due to its recognized risks, independent of the broader regulations described by COSHH.

Asbestos has long been acknowledged for its unique hazardous properties, including its role in respiratory diseases like asbestosis and lung cancer. Therefore, in the context of COSHH, asbestos is excluded from the general coverage of substances that COSHH typically addresses, necessitating that it be handled under separate, more stringent legislation.

On the other hand, dust, fumes, and gases are more general categories of substances that can be harmful and are covered under the regulations laid out by COSHH since they can arise from a variety of activities in the workplace and have various potential health effects. Each of these substances can pose health risks depending on their nature and the level of exposure, making them relevant to COSHH principles.