Latest news with #Zone0
Los Angeles Times
25-06-2025
- Science
- Los Angeles Times
Letters to the Editor: Proposed Zone 0 fire-safety regulation needs more scrutiny
To the editor: The Los Angeles Times has seen fit to print an article about an insurance industry-sponsored 'test' purporting to show the effectiveness of California's proposed Zone 0 regulation ('In a test, one home burns, the other is unscathed. A lesson for fire-proofing L.A.?,' June 11). This would require homeowners to remove all vegetation within five feet of homes. There are several facts that this article ignores about the 'test' and Zone 0: The test failed to consider science showing that mature, healthy vegetation can provide protection to homes in urban wildfires, as an opinion piece in the L.A. Times pointed out recently. What if this experiment had included a fire-hardened home surrounded by healthy vegetation? What if this experiment included a Zone 0-compliant home subjected to flying embers and winds of 60-80 mph? The insurance industry stands to benefit significantly by Zone 0 regulation because it potentially hands them yet another reason to cancel California homeowners' policies. All it takes is a drone flyover for insurers to know what's growing on your lot. The regulation is profoundly regressive. Homeowners with the least resources will pay disproportionately more to come into compliance with Zone 0. Homeowners with small lots will have disproportionately less green space where their children can play. Lastly, the article fails to mention the grave impact on California's environment that the wholesale removal of millions of plants and mature trees would have. Defensible space is critical to fire prevention. I hope future reporting will explore the motives of Zone 0 advocates and the science behind more nuanced approaches. Susan Woolley, Altadena
Fast Company
04-06-2025
- Health
- Fast Company
What California's plant ban overlooks for wildfire safety
One of the most striking patterns in the aftermath of many urban fires is how much unburned green vegetation remains amid the wreckage of burned neighborhoods. In some cases, a row of shrubs may be all that separates a surviving house from one that burned just a few feet away. As scientists who study how vegetation ignites and burns, we recognize that well-maintained plants and trees can actually help protect homes from wind-blown embers and slow the spread of fire in some cases. So, we are concerned about new wildfire protection regulations being developed by the state of California that would prohibit almost all plants and other combustible material within 5 feet of homes, an area known as 'Zone 0.' Wildfire safety guidelines have long encouraged homeowners to avoid having flammable materials next to their homes. But the state's plan for an 'ember-resistant zone,' being expedited under an executive order from Gov. Gavin Newsom, goes further by also prohibiting grass, shrubs, and many trees in that area. If that prohibition remains in the final regulation, it's likely to be met with public resistance. Getting these rules right also matters beyond California, because regulations that originate in California often ripple outward to other fire-prone regions. Lessons from the devastation Research into how vegetation can reduce fire risk is a relatively new area of study. However, the findings from plant flammability studies and examination of patterns of where vegetation and homes survive large urban fires highlight its importance. When surviving plants do appear scorched after these fires, it is often on the side of the plant facing a nearby structure that burned. That suggests that wind-blown embers ignited houses first: The houses were then the fuel as the fire spread through the neighborhood. We saw this repeatedly in the Los Angeles area after wildfires in January 2025. The pattern suggests a need to focus on the many factors that can influence home losses. Several guides are available that explain steps homeowners can take to help protect houses, particularly from wind-blown embers, known as home hardening. For example, installing rain gutter covers to keep dead leaves from accumulating, avoiding flammable siding, and ensuring that vents have screens to prevent embers from getting into the attic or crawl space can lower the risk of the home catching fire. However, guidance related to landscaping plants varies greatly and can even be incorrect. For example, some 'fire-safe' plant lists contain species that are drought tolerant but not necessarily fire resistant. What matters more for keeping plants from becoming fuel for fires is how well they're maintained and whether they're properly watered. How a plant bursts into flames When living plant material is heated by a nearby energy source, such as a fire, the moisture inside it must be driven off before it can ignite. That evaporation cools the surrounding area and lowers the plant's flammability. In many cases, high moisture can actually keep a plant from igniting. We've seen this in some of our experimental work and in other studies that test the flammability of ornamental landscaping. With enough heat, dried leaves and stems can break down and volatilize into gases. And, at that point, a nearby spark or flame can ignite these gases and set the plant on fire. Even when the plant does burn, however, its moisture content can limit other aspects of flammability, such as how hot it burns. Up to the point that they actually burn, green, well-maintained plants can slow the spread of a fire by serving as 'heat sinks,' absorbing energy and even blocking embers. This apparent protective role has been observed in both Australia and California studies of home losses. How often vegetation buffers homes from igniting during urban conflagrations is still unclear, but this capability has implications for regulations. California's 'Zone 0' regulations The Zone 0 regulations California's State Board of Forestry is developing are part of broader efforts to reduce fire risk around homes and communities. They would apply in regions considered at high risk of wildfires or defended by Cal Fire, the state's firefighting agency. Many of the latest Zone 0 recommendations, such as prohibiting mulch and attached fences made of materials that can burn, stem from large-scale tests conducted by the National Institute of Standards and Technology and the Insurance Institute for Business and Home Safety. These features can be systematically analyzed. But vegetation is far harder to model. The state's proposed Zone 0 regulations oversimplify complex conditions in real neighborhoods and go beyond what is currently known from scientific research regarding plant flammability. A mature, well-pruned shrub or tree with a high crown may pose little risk of burning and can even reduce exposure to fires by blocking wind and heat and intercepting embers. Aspen trees, for example, have been recommended to reduce fire risk near structures or other high-value assets. In contrast, dry, unmanaged plants under windows or near fences may ignite rapidly and make it more likely that the house itself will catch fire. As California and other states develop new wildfire regulations, they need to recognize the protective role that well-managed plants can play, along with many other benefits of urban vegetation. We believe the California proposal's current emphasis on highly prescriptive vegetation removal, instead of on maintenance, is overly simplistic. Without complementary requirements for hardening the homes themselves, widespread clearing of landscaping immediately around homes could do little to reduce risk and have unintended consequences.
