- Carry out a desk study to identify ground gas sources before work starts.
- Monitor for methane, CO2, O2, and H2S as a minimum at all excavations.
- Calibrate gas detection instruments to the manufacturer's schedule.
- Record all monitoring results and compare against trigger and action levels.
- Ventilate excavations and enclosed spaces before and during work.
- Ensure all operatives know alarm thresholds and the evacuation procedure.
- Use intrinsically safe equipment where flammable gases may be present.
- Re-monitor after breaks, shift changes, or any change in conditions.
- Include ground gas risk in the site-specific risk assessment.
- Report any unexpected odours, readings, or symptoms immediately.
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- DON'T enter any excavation without checking the atmosphere first.
- DON'T rely on smell to detect gases — some are odourless or deaden senses.
- DON'T use uncalibrated or out-of-date gas detection equipment.
- DON'T ignore low-level readings — they can increase rapidly.
- DON'T smoke, use naked flames, or create sparks near gas risk areas.
- DON'T assume gas levels are safe because they were clear earlier today.
- DON'T work in oxygen-depleted atmospheres without breathing apparatus and rescue.
- DON'T store monitoring equipment near contaminants affecting sensor accuracy.
- DON'T dismiss headaches or dizziness — these may indicate gas exposure.
- DON'T skip monitoring because the site looks or smells normal.
See also: Contaminated Land Safety Awareness | Atmospheric Monitoring and Gas Testing
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