When determining the need for a shutdown, which of the following gas types would be monitored?

Monitoring for combustible or toxic gases is crucial when determining the need for a shutdown because these gases can pose serious safety hazards in a working environment. When levels of these gases exceed safe thresholds, they can lead to explosions, fires, or health crises among personnel. Therefore, continuous monitoring of combustible or toxic gases is essential in ensuring both operational safety and compliance with regulatory standards.

In contrast, inert gases do not react with other substances and generally do not pose the same level of risk in terms of combustion or toxicity. Non-combustible gases, while they may present other concerns, are typically not the primary focus for immediate shutdown protocols in the context of fire or explosion hazards. Neutral gases also lack the properties that would necessitate urgent monitoring for shutdown purposes. Thus, the decision to monitor is primarily driven by the immediate risks associated with combustible or toxic gases, necessitating vigilance to protect equipment and personnel.