05/22/2026
Confined Space Training: Why Air Testing Comes First
One reading at the opening is not enough.
In confined space work, hazardous atmospheres can exist at different levels inside the space. Some gases rise. Some settle. Some collect in pockets where ventilation is poor.
That means the air near the entry point may test safe while the air deeper inside the space may not be.
Before entry, workers need to think about where the sample is being taken.
Air testing should consider:
The top, middle, and bottom of the space
Low points, corners, sumps, or pits
Areas near sludge, residue, or standing liquid
Spaces connected to pipes, valves, or process lines
Whether conditions could change during the work
Air testing comes first because it helps answer the most important question:
Is the atmosphere safe throughout the space or just at the opening?
In confined space work, the location of the reading matters.
A safe reading in one area does not guarantee a safe atmosphere everywhere.
