Here's why:

* No visible flame: Smoldering fires are characterized by a low, glowing heat without a visible flame.

* No smoke (initially): In the very early stages of smoldering, there might not be much smoke, but as the fire progresses, smoke can develop.

* Gases are being produced: Smoldering releases gases, including carbon monoxide, which is highly dangerous.

Let me know if you'd like to know more about the stages of a fire!