Published January 2026.

This guidance covers the requirement for COSHH assessments for all substances during an intrusive ground investigation and monitoring to prevent ill health in workers.

During a ground investigation, numerous substances can be brought to site and utilised. These may be hazardous and harmful to health. Under The Control of Substances Hazardous to Health (COSHH) Regulations 2002 an employer is required to assess the harmful nature of all substances used, and to protect employees from harm. Examples of substances include line marker spray paint, diesel, antibacterial handwash, pH buffer solutions, cement, bentonite, drilling mud, motor oil and acid solutions and methanol (used as preservatives for chemical laboratory samples).

Harmful substances can also be encountered in the soil and groundwater being investigated and assessment of the harm posed by these substances is also required although they do not strictly fall within COSHH regulations. Section 1.6 provides information on how COSHH can be applied to the investigation of potentially contaminated sites.

Note: the COSHH Regulations do not cover: lead, asbestos or radioactive substances which each have their own regulations.