Environment, Health and Safety

4.9 Unattended Operations

4.9 Unattended Operations

Unattended Operations

Unattended operations are activities in which laboratory equipment or processes continue to run without personnel present. When unattended operations are necessary, they must be deliberately planned and set up to limit the likelihood and consequences of equipment failure, utility interruption, or other foreseeable abnormal conditions.

Before leaving an operation unattended, laboratory personnel should identify the hazards involved, evaluate what could reasonably go wrong, and ensure appropriate controls are in place. Additional precautions are especially important when unattended operations involve hazardous chemicals, elevated temperatures or pressures, electrical hazards, or other conditions with the potential for significant impact.

Notification and identification

For unattended operations involving significant hazards, the laboratory should remain visibly occupied and clearly identified. A light should be left on, and an information or warning sign should be posted on the laboratory door or another conspicuous location that can be read without placing responders at risk.

The sign should include:

  • A brief description of the operation in progress
  • The chemicals or materials involved
  • The primary hazards present (e.g., heat, pressure, electrical)
  • The name and contact number of the responsible individual, with a secondary contact if available

Planning and safeguards

Unattended operations should be designed so that reasonably foreseeable failures do not escalate into more serious incidents. Risk is reduced most effectively by combining multiple layers of protection and avoiding reliance on a single safeguard.

  • Use secondary containment (e.g., trays or pans) to capture potential leaks or spills
  • Use safety shields and keep fume hood sashes lowered to contain splashes, fragments, or releases
  • Remove unnecessary chemicals, equipment, or combustible materials from the immediate area
  • Use automatic shutoff devices or interlocks where feasible (e.g., loss of cooling water, over-temperature protection)
  • Connect critical equipment to emergency power outlets when loss of power could introduce additional hazards

If hazards cannot be adequately controlled for unattended operation, the activity should be modified, delayed, or actively supervised until appropriate controls can be implemented.

Principal Investigators and laboratory supervisors are responsible for establishing expectations and providing resources to support safe unattended operations. Laboratory personnel are expected to follow approved procedures and to pause work or raise concerns when unattended operations present unmanaged risk.