As the Eaton and Palisades fires rapidly jumped between tightly packed houses, the proactive steps some residents took to retrofit their homes with fire-resistant building materials and to clear flammable brush became a significant indicator of a home’s fate.

Early adopters who cleared vegetation and flammable materials within the first five feet of their houses’ walls — in line with draft rules for the state’s hotly debated “zone zero” regulations — fared better than those who didn’t, an on-the-ground investigation from the Insurance Institute for Business and Home Safety published Wednesday found.

Over a week in January, while the fires were still burning, the insurance team inspected more than 250 damaged, destroyed and unscathed homes in Altadena and Pacific Palisades.

On properties where the majority of zone zero land was covered in vegetation and flammable materials, the fires destroyed 27% of homes; On properties with less than a quarter of zone zero covered, only 9% were destroyed.

The Insurance Institute for Business and Home Safety, an independent research nonprofit funded by the insurance industry, performed similar investigations for Colorado’s 2012 Waldo Canyon fire, Hawaii’s 2023 Lahaina fire and California’s Tubbs, Camp and Woolsey fires of 2017 and 2018.

While a handful of recent studies have found homes with sparse vegetation in zone zero were more likely to survive fires, skeptics say it does not yet amount to a scientific consensus.

Travis Longcore, senior associate director and an adjunct professor at the UCLA Institute of the Environment and Sustainability, cautioned that the insurance nonprofit’s results are only exploratory: The team did not analyze whether other factors, such as the age of the homes, were influencing their zone zero analysis, and how the nonprofit characterizes zone zero for its report, he noted, does not exactly mirror California’s draft regulations.

Meanwhile, Michael Gollner, an associate professor of mechanical engineering at UC Berkeley who studies how wildfires destroy and damage homes, noted that the nonprofit’s sample does not perfectly represent the entire burn areas, since the group focused specifically on damaged properties and were constrained by the active firefight.

Nonetheless, the nonprofit’s findings help tie together growing evidence of zone zero’s effectiveness from tests in the lab — aimed at identifying the pathways fire can use to enter a home — with the real-world analyses of which measures protected homes in wildfires, Gollner said.

A recent study from Gollner looking at more than 47,000 structures in five major California fires (which did not include the Eaton and Palisades fires) found that of the properties that removed vegetation from zone zero, 37% survived, compared with 20% that did not.

Once a fire spills from the wildlands into an urban area, homes become the primary fuel. When a home catches fire, it increases the chance nearby homes burn, too. That is especially true when homes are tightly packed.

When looking at California Department of Forestry and Fire Protection data for the entirety of the two fires, the insurance team found that “hardened” homes in Altadena and the Palisades that had noncombustable roofs, fire-resistant siding, double-pane windows and closed eaves survived undamaged at least 66% of the time, if they were at least 20 feet away from other structures.

But when the distance was less than 10 feet, only 45% of the hardened homes escaped with no damage.

“The spacing between structures, it’s the most definitive way to differentiate what survives and what doesn’t,” said Roy Wright, president and chief executive of the Insurance Institute for Business and Home Safety. At the same time, said Wright, “it’s not feasible to change that.”

Looking at steps that residents are more likely to be able to take, the insurance nonprofit found that the best approach is for homeowners to apply however many home hardening and defensible space measures that they can. Each one can shave a few percentage points off the risk of a home burning, and combined, the effect can be significant.

As for zone zero, the insurance team found a number of examples of how vegetation and flammable materials near a home could aid the destruction of a property.

At one home, embers appeared to have ignited some hedges a few feet away from the structure. That heat was enough to shatter a single pane window, creating the perfect opportunity for embers to enter and burn the house from the inside out. It miraculously survived.

At others, embers from the blazes landed on trash and recycling bins close to the houses, sometimes burning holes through the plastic lids and igniting the material inside. In one instance, the fire in the bin spread to a nearby garage door, but the house was spared.

Wooden decks and fences were also common accomplices that helped embers ignite a structure.

California’s current zone zero draft regulations take some of those risks into account. They prohibit wooden fences within the first five feet of a home; the state’s zone zero committee is also considering whether to prohibit virtually all vegetation in the zone or to just limit it (regardless, well-maintained trees are allowed).

On the other hand, the draft regulations do not prohibit keeping trash bins in the zone, which the committee determined would be difficult to enforce. They also do not mandate homeowners replace wooden decks.

The controversy around the draft regulations center around the proposal to remove virtually all healthy vegetation, including shrubs and grasses, from the zone.

Critics argue that, given the financial burden zone zero would place on homeowners, the state should instead focus on measures with lower costs and a significant proven benefit.

“A focus on vegetation is misguided,” said David Lefkowith, president of the Mandeville Canyon Assn.

At its most recent zone zero meeting, the Board of Forestry and Fire Protection directed staff to further research the draft regulations’ affordability.

“As the Board and subcommittee consider which set of options best balance safety, urgency, and public feasibility, we are also shifting our focus to implementation and looking to state leaders to identify resources for delivering on this first-in-the-nation regulation,” Tony Andersen, executive officer of the board, said in a statement. “The need is urgent, but we also want to invest the time necessary to get this right.”

Home hardening and defensible space are just two of many strategies used to protect lives and property. The insurance team suspects that many of the close calls they studied in the field — homes that almost burned but didn’t — ultimately survived thanks to firefighters who stepped in. Wildfire experts also recommend programs to prevent ignitions in the first place and to manage wildlands to prevent intense spread of a fire that does ignite.

For Wright, the report is a reminder of the importance of community. The fate of any individual home is tied to that of those nearby — it takes a whole neighborhood hardening their homes and maintaining their lawns to reach herd immunity protection against fire’s contagious spread.

“When there is collective action, it changes the outcomes,” Wright said. “Wildfire is insidious. It doesn’t stop at the fence line.”

The dreaded norovirus — the “vomiting bug” that often causes stomach flu symptoms — is climbing again in California, and doctors warn that a new subvariant could make even more people sick this season.

In L.A. County, concentrations of norovirus are already on the rise in wastewater, indicating increased circulation of the disease, the local Department of Public Health told the Los Angeles Times.

Norovirus levels are increasing across California, and the rise is especially notable in the San Francisco Bay Area and L.A., according to the California Department of Public Health.

And the rate at which norovirus tests are confirming infection is rising nationally and in the Western U.S. For the week that ended Nov. 22, the test positivity rate nationally was 11.69%, up from 8.66% two months earlier. In the West, it was even worse: 14.08%, up from 9.59%, according to the U.S. Centers for Disease Control and Prevention.

Norovirus is extraordinarily contagious, and is America’s leading cause of vomiting and diarrhea, according to the CDC. Outbreaks typically happen in the cooler months between November and April.

Clouding the picture is the recent emergence of a new norovirus strain — GII.17. Such a development can result in 50% more norovirus illness than typical, the CDC says.

“If your immune system isn’t used to something that comes around, a lot of people get infected,” said Dr. Peter Chin-Hong, an infectious diseases expert at UC San Francisco.

During the 2024-25 winter season, GII.17 overthrew the previous dominant norovirus strain, GII.4, that had been responsible for more than half of national norovirus outbreaks over the preceding decade. The ancestor of the GII.17 strain probably came from a subvariant that triggered an outbreak in Romania in 2021, according to CDC scientists.

GII.17 vaulted in prominence during last winter’s norovirus surge and was ultimately responsible for about 75% of outbreaks of the disease nationally.

The strain’s emergence coincided with a particularly bad year for norovirus, one that started unusually early in October 2024, peaked earlier than normal the following January and stretched into the summer, according to CDC scientists writing in the journal Emerging Infectious Diseases.

During the three prior seasons, when GII.4 was dominant, norovirus activity had been relatively stable, Chin-Hong said.

Norovirus can cause substantial disruptions — as many parents know all too well. An elementary school in Massachusetts was forced to cancel all classes on Thursday and Friday because of the “high volume of stomach illness cases,” which was suspected to be driven by norovirus.

More than 130 students at Roberts Elementary School in Medford, Mass., were absent Wednesday, and administrators said there probably wouldn’t be a “reasonable number of students and staff” to resume classes Friday. A company was hired to perform a deep clean of the school’s classrooms, doorknobs and kitchen equipment.

Some places in California, however, aren’t seeing major norovirus activity so far this season. Statewide, while norovirus levels in wastewater are increasing, they still remain low, the California Department of Public Health said.

There have been 32 lab-confirmed norovirus outbreaks reported to the California Department of Public Health so far this year. Last year, there were 69.

Officials caution the numbers don’t necessarily reflect how bad norovirus is in a particular year, as many outbreaks are not lab-confirmed, and an outbreak can affect either a small or large number of people.

Between Aug. 1 and Nov. 13, there were 153 norovirus outbreaks publicly reported nationally, according to the CDC. During the same period last year, there were 235.

UCLA hasn’t reported an increase in the number of norovirus tests ordered, nor has it seen a significant increase in test positivity rates. Chin-Hong said he likewise hasn’t seen a big increase at UC San Francisco.

“Things are relatively still stable clinically in California, but I think it’s just some amount of time before it comes here,” Chin-Hong said.

In a typical year, norovirus causes 2.27 million outpatient clinic visits, mostly young children; 465,000 emergency department visits, 109,000 hospitalizations, and 900 deaths, mostly among seniors age 65 and older.

People with severe ongoing vomiting, profound diarrhea and dehydration may need to seek medical attention to get hydration intravenously.

“Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy,” the CDC says. Sports drinks can help with mild dehydration, but what may be more helpful are oral rehydration fluids that can be bought over the counter.

Children under the age of 5 and adults 85 and older are most likely to need to visit an emergency room or clinic because of norovirus, and should not hesitate to seek care, experts say.

“Everyone’s at risk, but the people who you worry about, the ones that we see in the hospital, are the very young and very old,” Chin-Hong said.

Those at highest risk are babies, because it doesn’t take much to cause potentially serious problems. Newborns are at risk for necrotizing enterocolitis, a life-threatening inflammation of the intestine that virtually only affects new babies, according to the National Library of Medicine.

Whereas healthy people generally clear the virus in one to three days, immune-compromised individuals can continue to have diarrhea for a long time “because their body’s immune system can’t neutralize the virus as effectively,” Chin-Hong said.

The main way people get norovirus is by accidentally drinking water or eating food contaminated with fecal matter, or touching a contaminated surface and then placing their fingers in their mouths.

People usually develop symptoms 12 to 48 hours after they’re exposed to the virus.

Hand sanitizer does not work well against norovirus — meaning that proper handwashing is vital, experts say.

People should lather their hands with soap and scrub for at least 20 seconds, including the back of their hands, between their fingers and under their nails, before rinsing and drying, the CDC says.

One helpful way to keep track of time is to hum the “Happy Birthday” song from beginning to end twice, the CDC says. Chin-Hong says his favorite is the chorus of Kelly Clarkson’s “Since U Been Gone.”

If you’re living with someone with norovirus, “you really have to clean surfaces and stuff if they’re touching it,” Chin-Hong said. Contamination is shockingly easy. Even just breathing out little saliva droplets on food that is later consumed by someone else can spread infection.

Throw out food that might be contaminated with norovirus, the CDC says. Noroviruses are relatively resistant to heat and can survive temperatures as high as 145 degrees.

Norovirus is so contagious that even just 10 viral particles are enough to cause infection. By contrast, it takes ingesting thousands of salmonella particles to get sick from that bacterium.

People are most contagious when they are sick with norovirus — but they can still be infectious even after they feel better, the CDC says.

The CDC advises staying home for 48 hours after infection. Some studies have even shown that “you can still spread norovirus for two weeks or more after you feel better,” according to the CDC.

The CDC also recommends washing laundry in hot water.

Besides schools, other places where norovirus can spread quickly are cruise ships, day-care centers and prisons, Chin-Hong said.

The most recent norovirus outbreak on a cruise ship reported by the CDC is on the ship AIDAdiva, which set sail on Nov. 10 from Germany. Out of 2,007 passengers on board, 4.8% have reported being ill. The outbreak was first reported on Nov. 30 following stops that month at the Isle of Portland, England; Halifax, Canada; Boston; New York City; Charleston, S.C.; and Miami.

According to CruiseMapper, the ship was set to make stops in Puerto Vallarta on Saturday, San Diego on Tuesday, Los Angeles on Wednesday, Santa Barbara on Thursday and San Francisco between Dec. 19-21.

The California Department of Fish and Wildlife has recommended granting threatened species status to roughly 1,400 mountain lions roaming the Central Coast and Southern California, pointing to grave threats posed by freeways, rat poison and fierce wildfires.

The determination, released Wednesday, is not the final say but signals a possibility that several clans of the iconic cougars will be listed under the California Endangered Species Act.

It’s a move that supporters say would give the vulnerable animals a chance at recovery, but detractors have argued would make it harder to get rid of lions that pose a safety risk to people and livestock.

The recommendation was “overdue,” Charlton Bonham, director of the state wildlife department, said during a California Fish and Game Commission meeting.

It arrives about six years after the Center for Biological Diversity and Mountain Lion Foundation petitioned the commission to consider listing a half-dozen isolated lion populations that have suffered from being hit by cars, poisoned by rodenticides and trapped by development.

The following year, in 2020 the Commission found the request might be warranted, giving the lions temporary endangered species protections as “candidates” for listing. It also prompted the state wildlife department to put together a report to inform the commission’s final decision.

The next step is for state wildlife commissioners to to vote on the protections, possibly in February.

Brendan Cummings, conservation director for Center for Biological Diversity, hailed the moment as “a good day, not just for mountain lions, but for Californians.”

If the commissioners adopt the recommendation, as he believes they will, then the “final listing of the species removes any uncertainty about the state’s commitment to conserving and recovering these ecologically important, charismatic and well-loved species that are so much a part of California.”

The report recommends listing lions “in an area largely coinciding” with what the petitioners requested, which includes the Santa Ana, San Gabriel, San Bernardino, Santa Monica, Santa Cruz and Tehachapi mountains.

It trims off portions along the northern and eastern borders of what was proposed, including agricultural lands in the Bay Area and a southeastern portion of desert — areas where state experts had no records of lions, according to Cummings.

Officials in the report note that most of the lion groups proposed for listing are contending with a lack of gene flow because urban barriers keep them from reaching one another.

In Southern California, lions have shown deformities from inbreeding, including kinked tails and malformed sperm. There’s an almost 1 in 4 chance, according to research, that mountain lions could become extinct in the Santa Monica and Santa Ana mountains within 50 years.

The late P-22 — a celebrity mountain lion that inhabited Griffith Park – personified the tribulations facing his kind. Rat poison and car collisions battered him from the inside out. He was captured and euthanized in late 2022, deemed too sick to return to the wild because of injuries and infection.

For some species, protections come in the form of stopping chainsaws or bulldozers. But imperiled lions, Cummings said, need their habitats stitched together in the form of wildlife crossings — such as the gargantuan one being built over the 101 Freeway in Agoura Hills. He added that developments that could restrict their movement should get more scrutiny under the proposed protections.

Critics of the effort to list lion populations have said that it will stymie residential and commercial projects.

California is home to roughly 4,170 mountain lions, according to the recent report, but not all are equal in their struggle.

Many lion populations, particularly in northwest coastal forests, are hearty and healthy.

Protections are not being sought for those cats. Some, in fact, would like to see their numbers reduced amid some high-profile conflicts.

Bonham, the director of the state Department of Fish and Wildlife, spoke to concerns about public safety at the recent meeting, alluding to the tragic death of young man who was mauled by a cougar last year in Northern California.

“These are really delicate issues and the conversation I know in the coming years is going to have to grapple with all that,” said Bonham, who will be stepping down this month after nearly 15 years in his role.

California’s lions already enjoy certain protections. In 1990, voters approved a measure that designated them a “specially protected species” and banned hunting them for sport.