Q: How are wildfires put out?

A: Three things are needed to keep a fire going: fuel, oxygen, and heat. The total fire suppression effort removes one or more of these necessary ingredients. For example, fire lines remove vegetation (a fire's access to fuel). The fire is sometimes smothered in dirt to remove its oxygen supply. Water and retardant may also be used to cool flames and remove heat.

Q: What's the difference between "containment" of a fire and "controlling" a fire?

A: A fire is not considered "controlled" until it's all the way out. Until then, firefighters work toward "containing" the fire. Here's one way to think of it: Think of a container -- say, a mason jar. A fire is contained when it's all "bottled in," like in a container. The fire may still be burning, but if a distinct fire line is built around the entire perimeter so that there is no chance for the fire to escape or spot over outside the line, then the fire fighters declare the fire "contained."

After containing the fire, the next step is to get it under control -- that is, make sure it is dead out -- no hot spots, no floating embers, nothing that will flare up again if a breeze should come along.

Q: What is the difference between a "prescribed fire" and a "wildfire?"

A: A wildfire is an unplanned or unwanted fire. Such a fire may be a threat to resources, structures, or people. Despite the cause, these fires are suppressed using strategies and tactics appropriate to the threat.

A prescribed fire is one that is started intentionally by qualified, trained personnel. There are many reasons why the government would choose to start a fire intentionally, such as reducing the number of large, old trees to give ground vegetation a chance to grow and improve habitat for wildlife. Another reason may be to reduce the amount of fuel that would otherwise burn in a large, catastrophic wildfire. Like a doctor's prescription, there are specific conditions that must be met before the agency lights a prescribed fire, including favorable temperatures, low winds, and optimum humidity.

Other precautions also include a well-defined containment area to minimize the possibility of the fire escaping. Even if most of these conditions are in place, the supervisors in charge of igniting the fire may stop the ignition if they determine that weather conditions are too unstable, that the lines are not sufficiently defined, if enough fire fighting equipment and people are not available, if there is a threat to public or fire fighter safety, or for many other reasons. If these conditions are not in place, just as if the doctor's prescription is not followed carefully, the "remedy" may prove just as harmful as the problem.

Q: What is "mop-up?"

A: Once the fire stops spreading, firefighters begin the task of mop-up. This involves cooling burning areas inside the fire line with tools and water, managing burning debris to reduce further spread, and "blackening."