What is the correct order of atmospheric testing?

The correct order of atmospheric testing is based on the importance of identifying the most critical atmospheric conditions that could pose immediate risks to workers in a confined space. The first step is to test for oxygen levels. This is essential because a deficiency or excess of oxygen can significantly affect human health and safety — too little oxygen can lead to unconsciousness, while too much can create fire hazards.

Following the oxygen test, the next step is to check for flammable gases and vapors. Identifying flammables after ensuring that there is an adequate oxygen level is crucial to prevent any ignition sources from leading to explosions or fires in the presence of combustible materials.

The third step is to test for toxic gases. These can pose serious health threats, and it's important to establish the presence of harmful substances after confirming that the oxygen levels and flammable materials are managed.

Lastly, testing for any other atmospheric parameters allows for a comprehensive understanding of the environment, which could include additional harmful substances or conditions specific to that confined space.

This order prioritizes safety by first addressing the most critical concerns of oxygen and fire hazards before evaluating toxic exposures, ensuring a deliberate and methodical approach to atmospheric testing in confined spaces.