International

Scientists discover how air pollution triggers lung cancer

AFP | by Daniel Lawler and Isabelle Cortes

Scientists said Saturday they had identified the mechanism through which air pollution triggers lung cancer in non-smokers, a discovery one expert hailed as “an important step for science — and for society”.

The research illustrated the health risk posed by the tiny particles produced by burning fossil fuels, sparking fresh calls for more urgent action to combat climate change.

It could also pave the way for a new field of cancer prevention, according to Charles Swanton of the UK’s Francis Crick Institute.

Swanton presented the research, which has not yet been published in a peer-reviewed journal, at the European Society for Medical Oncology’s annual conference in Paris.

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Air pollution has long been thought to be linked to a higher risk of lung cancer in people who have never smoked.

“But we didn’t really know whether pollution was directly causing lung cancer — or how,” Swanton told AFP.

Traditionally it has been thought that exposure to carcinogens, such as those in cigarette smoke or pollution, causes DNA mutations that then become cancer.

But there was an “inconvenient truth” with this model, Swanton said: previous research has shown that the DNA mutations can be present without causing cancer — and that most environmental carcinogens do not cause the mutations.

His study proposes a different model.

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A future cancer pill?

The research team from the Francis Crick Institute and University College London analysed the health data of more than 460,000 people in England, South Korea and Taiwan.

They found that exposure to tiny PM2.5 pollution particles — which are less than 2.5 microns across — led to an increased risk of mutations in the EGFR gene.

In laboratory studies on mice, the team showed that the particles caused changes in the EGFR gene as well as in the KRAS gene, both of which have been linked to lung cancer.

Finally, they analysed nearly 250 samples of human lung tissue never exposed to carcinogens from smoking or heavy pollution.

Even though the lungs were healthy, they found DNA mutations in 18 percent of EGFR genes and 33 percent of KRAS genes.

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“They’re just sitting there,” Swanton said, adding that the mutations seem to increase with age.

“On their own, they probably are insufficient to drive cancer,” he said.

But when a cell is exposed to pollution it can trigger a “wound-healing response” that causes inflammation, Swanton said.

And if that cell “harbours a mutation, it will then form a cancer”, he added.

“We’ve provided a biological mechanism behind what was previously an enigma,” he said.

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In another experiment on mice, the researchers showed that an antibody could block the mediator — called interleukin 1 beta — which sparks the inflammation, stopping cancer from getting started in the first place.

Swanton said he hoped the finding would “provide fruitful grounds for a future of what might be molecular cancer prevention, where we can offer people a pill, perhaps every day, to reduce the risk of cancer”.

Revolutionary

Suzette Delaloge, who heads the cancer prevention programme at France’s Gustave Roussy institute, said the research was “quite revolutionary, because we had practically no prior demonstration of this alternative way of cancer forming.

“The study is quite an important step for science — and for society too, I hope,” she told AFP.

“This opens a huge door, both for knowledge but also for new ways to prevent” cancer from developing, said Delaloge, who was not involved in the research but discussed it at the conference on Saturday.

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“This level of demonstration must force authorities to act on an international scale.”

Tony Mok, an oncologist at the Chinese University of Hong Kong, called the research “exciting”.

“It means that we can ask whether, in the future, it will be possible to use lung scans to look for pre-cancerous lesions in the lungs and try to reverse them with medicines such as interleukin 1 beta inhibitors,” he said.

Swanton called air pollution a “hidden killer”, pointing to research estimating it is linked to the deaths of more than eight million people a year — around the same number as tobacco.

Other research has linked PM2.5 to 250,000 deaths annually from lung cancer alone.

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“You and I have a choice about whether we smoke or not, but we do not have a choice about the air we breathe,” said Swanton, who is also the chief clinician at Cancer Research UK, which was the main funder of the research.

“Given that probably five times as many people are exposed to unhealthy levels of pollution than tobacco, you can see this is quite a major global problem,” he added.

“We can only tackle it if we recognise the really intimate links between climate health and human health.”

International

Three U.S. Executions Set for Same Day as Trump Pushes to Expand Death Penalty

The death penalty has been abolished in 23 of the 50 U.S. states, while three others —California, Oregon and Pennsylvania— currently have moratoriums in place.

The United States is set to carry out three executions on the same day, a rare occurrence that has not happened since 2010, according to the nonprofit Death Penalty Information Center.

President Donald Trump has sought to expand the use of capital punishment for what he describes as “the most heinous crimes.” In April, the Department of Justice proposed expanding execution methods to include firing squads, lethal gas and electrocution.

Tennessee is scheduled to execute Anthony Darrell Dugard Hines, 66, on Thursday. He was sentenced to death for the 1985 murder of a woman, according to local media.

In Oklahoma, Carlos Cuesta-Rodríguez, 70, is scheduled to be executed for a 2003 murder.

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Meanwhile, Alabama plans to execute Jeremy Williams, 42, who was sentenced to death for the rape and murder of a five-year-old girl.

The United States carried out 47 executions in 2025, the highest number since 2009, when 52 executions were recorded.

Florida conducted the largest number of executions last year, with 19, followed by Alabama, South Carolina and Texas, with five each.

Of the executions carried out in 2025, 39 were conducted by lethal injection. Three were carried out by firing squad and five through nitrogen hypoxia, a method that involves forcing nitrogen gas into a face mask, depriving the prisoner of oxygen.

The United Nations has condemned nitrogen gas as a cruel and inhumane method of capital punishment.

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International

Colombia Earthquake Death Toll Reaches 265 as Rescue Teams Race Against Time

The 7.4-magnitude earthquake that struck Colombia on Monday, the strongest to hit the country this century, has so far left 265 people dead and around 3,500 injured.

In Cali, Pereira and other cities in western Colombia, rescue teams are working around the clock as they search for survivors. The first 72 hours following the earthquake will be reached at 7:34 a.m. local time (12:34 GMT), a critical window for rescue efforts as the chances of finding survivors generally decline significantly after that point.

Among those anxiously awaiting news is Valeria Cardona, a 26-year-old student searching for two of her cousins in Cali.

“We have some suspicions about their location, but there are no signs of life,” she said. “Hope is the last thing you lose, but we are anxious about receiving news we don’t want to hear.”

A team of members from the Topos Aztecas, the renowned Mexican volunteer rescue group, has also arrived in Cali to join the search. The rescuers had been working in neighboring Venezuela, where a double earthquake on June 24 left more than 6,000 people dead.

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“We all came from Venezuela, from La Guaira. The 41 days we spent working there made us stronger because we overcame hunger, pain and sleepless nights,” said Héctor Méndez, 80, president of Topos Aztecas.

Méndez encouraged those affected by the disaster not to lose hope and emphasized the commitment required from rescue teams during an emergency.

“Do not feel like victims. This is not an office or workshop schedule. This is real life, where the best part of the human spirit emerges. These are things of nature that happen,” he said.

International

German Authorities Investigate More Than 100 New Cases Against Convicted Nurse

German authorities announced Monday that they are investigating more than 100 additional cases involving a nurse who was sentenced to life in prison in November for the murder of 10 patients.

The man, who was 44 at the time of his conviction, worked in palliative care at a hospital in Würselen, near Aachen. He was also found guilty of 27 attempted murders.

Aachen prosecutors are now examining 121 new cases, a spokesperson for the office said.

Prosecutors leading the investigation are preparing a new indictment that could be filed next year. Nearly 40 bodies have so far been exhumed as part of the investigation, which covers alleged incidents dating back to September 2022.

Meanwhile, prosecutors in the city of Cologne are investigating 18 additional cases. According to a spokesperson, the oldest case dates back to 2010.

Before working at the Würselen hospital, the nurse is believed to have worked at a clinic in eastern Cologne, according to local media reports.

At the time of his November conviction, the court ruled that the severity of his crimes was particularly serious, a finding that would make it difficult for him to obtain early release after 15 years in prison.

Between December 2023 and May 2024, the nurse administered overdoses of sedatives or painkillers to terminally ill patients, most of them elderly, according to the indictment in the original case.

His alleged motive was to sedate patients who required care so that he could minimize his workload during night shifts, prosecutors said.

According to the indictment, the nurse worked «without enthusiasm» and «without motivation». When faced with patients requiring extensive care, he allegedly became «irritated» and showed a lack of empathy.

The case has revived painful memories in Germany of Niels Högel, a former nurse and serial killer who was sentenced to life imprisonment in June 2019 for the murders of at least 85 patients.