Science
James Reason, Who Used Swiss Cheese to Explain Human Error, Dies at 86
The story of how James Reason became an authority on the psychology of human error begins with a teapot.
It was the early 1970s. He was a professor at the University of Leicester, in England, studying motion sickness, a process that involved spinning his subjects round and round, and occasionally revealing what they had eaten for breakfast.
One afternoon, as he was boiling water in his kitchen to make tea, his cat, a brown Burmese named Rusky, sauntered in meowing for food. “I opened a tin of cat food,” he later recalled, “dug in a spoon and dolloped a large spoonful of cat food into the teapot.”
After swearing at Rusky, Professor Reason berated himself: How could he have done something so stupid?
The question seemed more intellectually engaging than making people dizzy, so he ditched motion sickness to study why humans make mistakes, particularly in high-risk settings.
By analyzing hundreds of accidents in aviation, railway travel, medicine and nuclear power, Professor Reason concluded that human errors were usually the byproduct of circumstances — in his case, the cat food was stored near the tea leaves, and the cat had walked in just as he was boiling water — rather than being caused by careless or malicious behavior.
That was how he arrived at his Swiss cheese model of failure, a metaphor for analyzing and preventing accidents that envisions situations in which multiple vulnerabilities in safety measures — the holes in the cheese — align to create a recipe for tragedy.
“Some scholars play a critical role in founding a whole field of study: Sigmund Freud, in psychology. Noam Chomsky, in linguistics. Albert Einstein, in modern physics,” Robert L. Sumwalt, the former chairman of National Transportation Safety Board, wrote in a 2018 blog post. “In the field of safety, Dr. James Reason has played such a role.”
Professor Reason died on Feb. 4 in Slough, a town about 20 miles west of London. He was 86.
His death, in a hospital, was caused by pneumonia, his family said.
A gifted storyteller, Professor Reason found vivid and witty ways to explain complicated ideas. At conferences, on TV news programs and in consultation with government safety officials around the world, he would sometimes deploy slices of cheese as props.
In one instructional video, he sat at his dining room table, which was set for a romantic dinner, with a bottle of wine, two glasses and a cutting board layered with cheese.
“In an ideal world, each defense would look like this,” he said, holding up a slice of cheese without holes. “It would be solid and intact.”
Then he reached for another slice, one with quarter-size cutouts. “But in reality, each defense is like this,” he said. “It has holes in it.”
The metaphor was easy to understand.
“All defenses have holes in them,” Professor Reason continued. “Every now and again, the holes line up so that there can be some trajectory of accident opportunity.”
To explain how the holes develop, he put them in two categories: active failures, or mistakes typically made by people who, for example, grab the cat food instead of the tea leaves; and latent conditions, or mistakes made in construction, written instructions or system design, like storing two scoopable substances near each other in a cabinet.
“Nearly all organizational accidents involve a complex interaction between these two sets of factors,” he wrote in his autobiography, “A Life in Error: From Little Slips to Big Disasters” (2013).
In the Chernobyl nuclear accident, he identified latent conditions that had been in existence for years: a poorly designed reactor; organizational mismanagement; and inadequate training procedures and supervision for frontline operators, who triggered the catastrophic explosion by making the error of turning off several safety systems at once.
“Rather than being the main instigators of an accident, operators tend to be the inheritors of system defects,” he wrote in “Human Error” (1990). “Their part is that of adding the final garnish to a lethal brew whose ingredients have already been long in the cooking.”
Professor Reason’s model has been widely used in health care.
“When I was in medical school, an error meant you screwed up, and you should just try harder to not screw up,” Robert Wachter, the chairman of the department of medicine at the University of California San Francisco, said in an interview. “And if it was really bad, you would probably get sued.”
In 1998, a doctor he had recently hired for a fellowship said he wanted to specialize in patient-safety strategy, to which Dr. Wachter replied, “What’s that?” There were no formal systems or methods in his hospital (or most others) to analyze and prevent errors, but there was plenty of blame to go around, most of it aimed at doctors and nurses.
This particular doctor had trained at Harvard Medical School, where they were incorporating Professor Reason’s ideas into patient-safety programs. Dr. Wachter, who began reading Professor Reason’s journal articles and books, said the Swiss cheese model was “an epiphany,” almost “like putting on a new pair of glasses.”
Someone given the wrong dose of medicine, he realized, could have been the victim of poor syringe design rather than a careless nurse. Another patient could have died of cardiac arrest because a defibrillator that was usually stored in the hallway had been taken to a different floor to replace one that had malfunctioned — and there was no system to alert anyone that it had been moved.
“When an error happens, our instinct can’t be to look at this at the final stage,” Dr. Wachter said, “but to look at the entirety of the system.”
When you do, he added, you realize that “these layers of protection are pretty porous in ways that you just didn’t understand until we opened our eyes to all of it.”
James Tootle was born on May 1, 1938, in Garston, a village in Hertfordshire, northwest of London. His father, Stanley Tootle, died in 1940, during World War II, when he was struck by shrapnel while playing cards in the bay window of his house. His mother, Hilda (Reason) Tootle, died when he was a teenager.
His grandfather, Thomas Augustus Reason, raised James, who took his surname.
In 1962, he graduated from the University of Manchester with a degree in psychology. He received his doctorate in 1967 from the University of Leicester, where he taught and conducted research before joining the faculty at the University of Manchester in 1977.
He married Rea Jaari, an educational psychologist, in 1964. She survives him, along with their daughters, Paula Reason and Helen Moss, and three grandchildren.
Throughout his career, Professor Reason’s surname was a reliable source of levity.
“The word ‘reason’ is, of course, widely used in the English language, but it does not describe what Jim is rightly famous for, namely ‘error,’” Erik Hollnagel, the founding editor of the International Journal of Cognition, Technology and Work, wrote in the preface to Professor Reason’s autobiography. “Indeed, ‘error’ is almost the opposite of ‘reason.’”
Still, it made sense.
“Jim has certainly brought reason to the study of error,” he wrote.
After years of heated debates among fire officials, scientists and local advocates, California’s Board of Forestry and Fire Protection released new proposed landscaping rules for fire-prone areas Friday that outline what residents can and can’t do within the first 5 feet of their homes.
Many of these proposed rules — designed to reduce the risk of a home burning down amid a wildfire — have wide support (or at least acceptance); however, the most contentious by far has been whether the state would allow healthy plants in the zone.
Many fire officials and safety advocates have essentially argued anything that can burn, will burn and have supported removing virtually anything capable of combustion from this zone within 5 feet of houses, dubbed “Zone Zero.” They point to the string of devastating urban wildfires in recent years as reason to move quickly.
Yet, researchers who study the array of benefits shade and extra foliage can bring to neighborhoods — and local advocates who are worried about the money and labor needed to comply with the regulations — have argued that this approach goes beyond what current science shows is effective. They have, instead, generally been in favor of allowing green, healthy plants within the zone.
The new draft regulations attempt to bridge the gap. They outline more stringent requirements to remove all plants in a new “Safety Zone” within a foot of the house and within a bigger buffer around potential vulnerabilities in a home’s wildfire armor, including windows that can shatter in extreme heat and wooden decks that can easily burst into flames. Everywhere else, the rules would allow residents to maintain some plants, although still with significant restrictions.
The rules generally do not require the removal of healthy trees — instead, they require giving these trees routine haircuts.
Once the state adopts a final version of the rules, homeowners would have three years to get their landscaping in order and up to five years for the bigger asks, including removing all vegetation from the Safety Zone and updating combustible fencing and sheds within 5 feet of the home. New constructions would have to comply immediately.
The rules only apply to areas with notable fire hazard, including urban areas that Cal Fire has determined have “very high” fire hazard and rural wildlands.
Officials with the Board will meet in Calabasas on Thursday from 1 p.m. to 7 p.m. to discuss the new proposal and hear from residents.
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Some L.A. residents are championing a proposed fire-safety rule, referred to as “Zone Zero,” requiring the clearance of flammable material within the first five feet of homes. Others are skeptical of its value.
Where is the Safety Zone?
The proposed Safety Zone with stricter requirements to remove all vegetation would extend 1 foot from the exterior walls of a house.
In a few areas with heightened vulnerabilities to wildfires, it extends further.
The Safety Zone covers any land under the overhang of roofs. If the overhang extends 3 feet, so does the Safety Zone in that area. It also extends 2 feet out from any windows, doors and vents, as well as 5 feet out from attached decks.
What plants would be allowed in the Safety Zone?
Generally, nothing that can burn can sit in the Safety Zone. This includes mulch, green grass, bushes and flowers.
What plants would be allowed in the rest of Zone Zero?
Homeowners can keep grasses (and other ground-covers, like moss) in this area, as long as it’s trimmed down to no taller than 3 inches.
The rules also allow small plants — from begonias to succulents — up to 18 inches tall as long as they are spaced out in groups. Residents can also keep spaced-out potted plants under this height, as long as they’re easily movable.
What about fences, trees and gates?
Any sheds or other outbuildings would need noncombustible exterior walls and roofs in Zone Zero — Safety Zone or not.
Residents would have to replace the first five feet of any combustible fencing or gates attached to their house with something made out of a noncombustible material, such as metal.
Trees generally would be allowed in Zone Zero. Homeowners would need to keep any branches one foot away from the walls, five feet above the roof and 10 feet from chimneys.
Residents would also have to remove any branches from the lower third of the tree (or up to 6 feet, whichever is shorter) to prevent fires on the ground from climbing into the canopy.
Some trees with trunks directly up against a house in this 1-foot buffer or under the roof’s overhang might need to go — since keeping branches away from the home could prove difficult (or impossible).
However, the board stressed it wants to avoid the removal of trees whenever feasible and encouraged homeowners to work with their local fire department’s inspectors to find case-by-case solutions.
What’s new and what’s not
Some of the rules discussed in Zone Zero are not new — they’ve been on the books for years, classified as requirements for Zone One, extending 30 feet from the home with generally less strict rules, and Zone Two, extending 100 feet from the house with the least strict rules.
For example, homeowners are already required to remove any dead or dying grasses, plants and trees. They also have to remove leaves, twigs and needles from gutters, and they already cannot keep exposed firewood in piles next to their house.
Residents are also already required to keep grasses shorter than 4 inches; Zone Zero lowers this by an inch.
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By Jorge Mitssunaga
April 17, 2026
Science
1,200% jump in kratom-related calls to poison control centers in last decade, analysis shows
Over the last decade, poison control centers around the country have received tens of thousands of calls from consumers of kratom products reporting adverse and life-threatening health effects, with researchers saying reports in 2025 reached a new level. California’s poison center is reporting similar findings.
Last month, researchers analyzed information from the National Poison Data System and found that between 2015 and 2025, poison control centers across the nation received 14,449 calls related to kratom. More than 23% of those calls, or 3,434, were made last year, according to a published report in the Centers for Disease Control and Prevention. That represents a more than 1,200% increase from 2015, when only 258 calls were reported.
Officers gather illegally grown kratom plants in 2019 in Phang Nha province, Thailand. The country decriminalized the possession and sale of kratom in 2021.
(Associated Press)
Kratom is derived from the leaves of Mitragyna speciosa, a tree native to Southeast Asia. It has a long history of being used for chronic pain or to boost energy and in the U.S., research points to Americans also using it to alleviate anxiety. In low doses, kratom appears to act as a stimulant but in high doses, it can have effects more like opioids.
But in the last few years, a synthetic form of kratom refined for its psychoactive compound, 7-hydroxymitragynine or 7-OH, has entered the market that is highly concentrated and not clearly labeled, leading to confusion and problems for consumers. The synthetic form gaining momentum in the market is sparking concern among public health officials because of its ability to bind to opioid receptors in the body, causing it to have a higher potential for abuse.
Los Angeles County leaders, meanwhile, have grappled with differentiating the two and regulating the products that come in the form of powder, capsules and drinks and have been linked to six county deaths. Sales of kratom and 7-OH products were banned in the county in November.
In reviewing the data, which did not differentiate whether callers had consumed natural or synthetic kratom, researchers set out to understand the effect of what they believe is a “rapidly evolving kratom market,” and highlight the role poison centers can play as an early warning surveillance system to detect new trends.
National Poison Data System findings
The data showed that over the last 10 years, 62% of the kratom-related calls to poison control centers were from people who said they consumed the drug by itself, and the other 38% were from people who combined it with another substance or substances.
Those who consumed kratom with another substance combined it most frequently with one or a combination of the following: alcohol, opioids, benzodiazepines (like Xanax or Valium), cannabis and cannabinoids, stimulants and antidepressants.
The data also broke down hospitalizations related to kratom — adults who took it alone or in combination and experienced “adverse” health effects; and adults who took it alone or in combination and experienced more serious “moderate” or “major” health effects, including death.
Kratom powder products are displayed in a smoke shop in Los Angeles in 2024.
(Michael Blackshire/Los Angeles Times)
Hospitalizations for adults who had consumed kratom alone and experienced adverse effects increased from 43 in 2015 to 538 in 2025. For those who took it in combination and were hospitalized with an adverse health effect, the total jumped from 40 in 2015 to 549 last year.
The numbers were even higher for hospitalizations where the health effects were more serious or fatal.
In 2015, there were 76 reports of people being hospitalized after taking kratom alone and experiencing a serious health effect or dying. By last year, that number had climbed to 919. The reports of serious health effects, including death, for those who took kratom in combination with another substance grew from 51 in 2015 to 725 last year.
The research does not break down kratom-related deaths by year but states that there were 233 deaths over the 10-year study period, or just over 3% of all 7,287 serious medical outcomes. Of the total number of kratom-related deaths, 184 cases involved the consumption of multiple substances.
What California’s poison control system found in its state data
The California Poison Control System is currently reviewing its data concerning kratom-related calls but an initial analysis shows parallels to the national report, said Rais Vohra, medical director of the state poison control system.
“We have about 10% of the national population and about 10% of the national call volume with poison control,” Vohra said. “And so, not surprisingly, we were able to identify over 900 cases of calls related to kratom in that same period.”
Local researchers are still deciphering the state data but they too have found that kratom-related calls are climbing.
“It’s accelerating, which I think is one of the main points of the [published] report,” Vohra said.
A majority of calls received by poison control come from healthcare facilities where “presumably someone has a problem … severe enough to warrant calling 911 or going to the emergency room, and that’s when our agency gets involved,” Vohra said.
Kait Brown, clinical managing director for America’s Poison Control Centers, said the fact that kratom and 7-OH are federally unregulated products sold online, in gas stations and smoke shops gives people across the country easy access.
And while kratom enthusiasts maintain that it has been used in its natural form for hundreds of years, “there are new formulations that are a little bit different than how people have used it, at least historically,” said William Eggleston, a pharmacist and the assistant clinical director of the Upstate New York Poison Center in Syracuse.
People are no longer consuming kratom only as a powder or capsule but also in the form of an energy shot or extract; it’s similar for synthetic, more concentrated 7-OH products.
When regional poison centers compare their findings and experiences with the analysis of calls in the National Poison Data System, Eggleston said, “undeniably there is an increase in calls related to kratom.”
“But when you put it in the bigger perspective of all the calls … this is still a very small percentage of what we’re dealing with on a day to day basis,” he said.
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