- When you might still breathe in contaminated air, despite other controls you have in place eg extraction systems
- When there is short-term or infrequent exposure and using other controls is impractical
- Whilst you are putting other controls in place
- When you need to provide RPE for safe exit in an emergency
- When you need to provide RPE for emergency work or when there is a temporary failure of controls
- When emergency rescue by trained personnel is necessary