NIST, Forest Service: Wildfire risk ratings were useful

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A rating system that assesses the risk that structures face from wildfires generally proved to be accurate, according to a report from the National Institute of Standards and Technology and the Forest Service that examined a major California wildfire from 2007.

That finding led the agencies to conclude that it's more effective to combat fires in areas with structures that are at low risk.

"Our data show that it's probably best to fight fires in low-exposure areas because there's a greater chance that they can be suppressed and with less danger to the crews," says the report's author, Alexander Maranghides, in a press release Sept. 3. Maranghides is the manager of the NIST Large Fire Laboratory.

The Witch Fire burned nearly 200,000 acres north of San Diego in 2007, destroyed more than 1,600 structures, killed two civilians and injured 39 firefighters.

NIST and the Forest Service collected extensive data on structures within the fire's perimeter and compared it with what the agencies' risk assessment system said was the risk of fire exposure. Defensive measures were more than twice as effective at low-exposure structures, the report (.pdf) says.

Defensive measures ranged from firefighters defending a home with multiple fire hoses to a homeowner extinguishing a fire with a garden hose, the report says.

In the release, Maranghides says the report was the first ever examination of the impact of a wildfire in relation to exposure risks and the effectiveness of defensive measures.

According to NIST, the risk assessment system it developed with the Forest Service is the first rating system that lets communities assess risks from wildfires on a building-by-building basis.

If homes rated high-risk are retrofitted to prevent catching on fire, that may be able to stifle a wildfire's growth and keep other structures from igniting.

For more:
- download the report, "A Case Study of a Community Affected by the Witch and Guejito Fires: Report #2--Evaluating the Effects of Hazard Mitigation Actions on Structure Ignitions" (.pdf)
- go to the NIST press release
- go to a description of the wildfire risk rating system

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