| Confined spaces, such as tanks and utility vaults | A worker can carry a detector while entering, moving through, and exiting the space. | Atmospheric testing may include oxygen, flammable gases or vapors, and relevant toxic gases. | Test the atmosphere as required by the entry procedure. A personal detector does not replace required pre-entry testing or continuous monitoring. |
| Maintenance across multiple work areas | One appropriately configured device can accompany a worker between changing job locations. | Monitor for the gases identified in the site hazard assessment and task-specific procedures. | Confirm the detector is suitable for the target gases and operating conditions before use. |
| Temporary tasks near a possible gas release | Workers can keep the detector close while performing short-duration inspections or repairs. | Personal monitoring can warn the wearer when the selected sensors detect a hazardous condition. | Alarm response, evacuation routes, and communication procedures should be established before work begins. |
| Changing or unfamiliar locations | A carried detector can provide monitoring where fixed detection may not cover a temporary work position. | Detection depends on the installed sensors, sampling method, and the gases present. | No single detector detects every gas. Select sensors based on the hazards identified for the location. |
| Work involving potential oxygen deficiency or enrichment | A portable instrument allows workers to monitor oxygen levels as they move through the work area. | Oxygen measurement can help identify an atmosphere outside the limits set by applicable procedures. | Oxygen readings alone do not establish that an atmosphere is safe; other atmospheric hazards may also be present. |
| Outdoor or dispersed work sites | Workers can carry monitoring equipment between separated tasks without relying solely on a detector at a fixed point. | Monitoring needs vary with the task, site conditions, and identified gas hazards. | Consider environmental conditions, instrument limitations, and the site’s inspection and alarm-response procedures. |
| Routine daily use | A wearable or handheld device keeps monitoring accessible during work rather than limiting it to one location. | Functional checks and calibration help confirm the instrument is operating as intended. | Follow the manufacturer’s instructions and workplace policy for bump testing, calibration, maintenance, and charging. |