While California burns, a new study shows that smoke is a silent killer of Fire

Air quality alerts have come into force in 11 states this week, while Canada Forest Smoke as well as California Gifford fires – which burned nearly 100,000 acres and are only 15% – distributed in the United States. While the planet warms up, such flames burn more intensely, smoke that can travel thousands of kilometers. In July, a group of republican members of the Congress went so far as to write an official complaint letter in Canada, arguing that the country’s smoke makes it difficult for Americans to enjoy summer.

But a growing corpus of research reinforces the knowledge that the smoke of forest fires is much more than a disadvantage – in fact, it actually kills many more people than the flames themselves. New research on the benefits of the Eaton palisades and fires that ravaged Los Angeles in January confirm this. Officially, conflagrations killed 30 people. But the new study suggests that this is an important underestimation, because it does not take into account the victims who may be dead miles from the flames while toxic smoke floated on the landscape. These researchers estimate that the number of deaths can be closer to 440 – or more.

This is “a big difference between what has been officially recorded in relation to what we consider according to our mortality modeling,” said Andrew C. Stokes, Demographer of Mortality at the Boston University School of Public Health, co-author of the research letter describing the results of the Journal of the American Medical Association. “Los Angeles has a solid system of investigation into death, and yet it is always very difficult for doctors and coroners to accurately attribute the cause of death during a natural disaster.”

The researchers found the additional deaths by examining the mortality data of the National Center for Health Statistics at the Centers for Disease Control and Prevention. From that, they could see how many people died in the County of Los Angeles in 2018, 2019 and 2024-that is to say how much Angelenos dies in a given year. (They jumped 2020 to 2023, because these years were not typical, given the deaths of the Pandemic Covid-19).).)

The Palisades and Eaton Fire raged throughout January, the researchers therefore examined the data from January 5 to February 1, 2025. On the basis of previous years, 5,931 deaths would be expected in the county during this period – but the period really experienced 6,371 deaths. The difference between these figures, 440, suggests that it is the number of people whose death can be attributed to fires.

These include not only people directly killed in the flames, but also those who suffered from abundant smoke pouring into the metropolis. This pollution can exacerbate conditions such as heart disease, chronic obstructive pulmonary disease and asthma. But these deaths have probably been assigned to the pre -existing conditions by the forensic doctors and coroners, rather than the triggering effects of the inhalation of forest smoke. There may also be people who died of more indirect effects of forest fires, such as the disruption of health systems or negative impacts on mental health.

“This shows that the flames were not the biggest killer,” said Jessica Yu, a researcher for the climate and energy policy of the University of Stanford who was not involved in research. “It’s also smoke.”

Forest fire smoke is a mixture of gas, water vapor and tiny particles, such as tar, carbon and soot, but it can contain hundreds of harmful chemicals. The smaller the particle matter, the larger the threat: the PM 2.5 particles, which are about thirty of the width of human hair, are small enough to enter the bloodstream. They can cause inflammation, trigger immune responses and worsen a number of pre -existing health problems. (While smoke moves into the atmosphere, it also transforms, producing ozone which still irritates the lungs.) Even a relatively brief exposure to the smoke of forest fires can have long -term health effects, especially for vulnerable communities which fight with poor air quality, even outside the season of forest fires. And because the PM 2.5 particles are so small, they can linger invisible in the air long after the end of a fire.

This new count of 440 deaths can always be an underestimation, and necessarily. (Previous research estimated that between 2008 and 2018, the smoke of forest fires in California was responsible for around 55,000 premature deaths, with an economic impact of more than $ 400 billion.) These researchers had only data between January 5 and February 1, but the impacts can be even more stretched, in particular that the cleaning teams have worked with the many toxicaries that have been raised Meldics, plastics and everything in homes, cars, cars and cars, and plastic smoke, and all others in homes, cars, and cars, and plastic smoke, and all others in homes, cars, and cars, and lead smoke, and all others in homes, cars and cars, and cars, and cars, and cars.

The study data also only covered the County of Los Angeles, while smoke could have killed even more people in neighboring jurisdictions. “Toxic do not respect the boundaries of the county,” said Stokes. “The neighboring counties were probably also deeply affected.”

Toxic do not respect international borders either. Relaxable forest fires across Canada have been throwing smoke in northern United States for months now. (This smoke can be even more toxic than usual, because fires burn in mining regions, where soils are strongly polluted by lead, mercury and arsenic.)

What is necessary, says Yu, is a more holistic approach to the response to disasters. EPA community programs could provide air filters to low -income neighborhoods. Advanced planning of the fire season in the health system could allow hospitals to allocate overvoltage capacity to affected areas, pre-positioning of mobile medical units and strengthen remote services to ensure that people can access care during the crisis.

“Events like this are not necessarily health risks of equal opportunity,” said Yu. “They affect people differently in colored communities and low-income neighborhoods. We really have to think about how to prioritize and target some of these health care responses. ”

Although it remains difficult to determine the real death tolls of forest fires, researchers think that their framework can be applied elsewhere. While the worsening of forest fires continues to expose more people to smoke, new research could give scientists and public health officials a better understanding of the threat.

“We think we have a set of generalizable tools,” said Stokes. “We have the modeling infrastructure that would allow us to look at other events and continue to disentangle this.”