A spate of ferocious wildfires across North America and Europe, worsened by the climate crisis, have incinerated homes and forests and forced thousands of people to flee. Previous fires suggest the effects of these blazes may linger for years to come.

The current fires and their plumes of smoke can appear to be a temporary, if immediate, crisis. Nearly 1,000 fires have sprung into life in the boreal forests of Canada, causing the evacuation of towns and toxic smoke to waft into major Canadian and US cities, prompting threats of retribution from Donald Trump, who bizarrely accused Canada of “poisoning” his country’s air.

Smoke is billowing from wildfires in the US too, amid the third major heatwave of the past month which has furthered dried out parched vegetation. Vast, lightening-sparked fires across Washington, eastern Oregon and Idaho have caused a plume of smoke so large that it could reach Florida.

In Europe, meanwhile, huge fires have gripped parts of the UK, France and Spain, causing the evacuation of more than 250,000 people.

The climate crisis, caused by the burning of fossil fuels, is known to be creating more fire-prone conditions around the world by drying out soils and plants. “The entire Iberian peninsula is suffering the effects of the climate emergency in a very specific way,” said Pedro Sánchez, Spain’s prime minister.

Scientists have also long been aware of the unhealthy consequences of wildfire smoke, which can trigger severe respiratory and cardiac problems in affected people. A recent study found that exposure to tiny particles carried in wildfire smoke will raise the risk of hospitalization for older people hundreds of miles away from fires.

“The cardiovascular toll of wildfire smoke reaches well beyond the fire lines and well beyond the day the sky turns orange,” said Kai Chen, associate professor of epidemiology at the Yale School of Public Health and study co-author.

But identifying the ongoing effects of wildfires long after they have been extinguished has been a more recent understanding. There are continuing challenges in Maui, the second largest of Hawaii’s islands, three years after wildfires there caused more than 100 deaths and razed several thousand buildings, a new report highlights.

While living and economic conditions have generally improved since the fires, many people in Maui are still struggling with health concerns such as poorer lung functions, higher blood pressure and mental health challenges, according to the Maui Wildfire Exposure Study, led by researchers at the University of Hawaii and released on Monday.

“The progress is real, and it should be recognized,” said Alika Maunakea, co-director of the study and a school of medicine professor at the University of Hawaii. “But the biological, emotional and social consequences of a disaster do not disappear on the same timeline as debris removal or reconstruction.”

Nearly half of all adults in the Maui study continued to report depressive symptoms, with nearly one in five differing from post-traumatic stress. The study, which conducted screenings of more than 2,500 participants, also found severe depressive symptoms and post-traumatic stress increased among children and adolescents, as did blood pressure readings and obesity levels.

“Children may appear resilient while still carrying significant emotional and physical effects beneath the surface,” said Christopher Knightsbridge, a mental health therapist based in Lahaina, a coastal town that was largely destroyed by the fires.

“Supporting children means supporting the entire family, including their housing, food security, daily routines and access to trusted care,” he added.

The researchers stressed that long-term monitoring and intervention is required following a major wildfire event due to impacts that can last for years afterwards. While the skies over North America and Europe will eventually clear of smoke after a tinderbox summer of fire, this climate change-driven era of wildfire is set to exact a lengthy toll.

As well better support for those directly affected by fires, experts say that authorities in smoke-affected areas could respond to the threat of repeated smoke exposure by creating “clean air centers” that people can flee to in order to escape smoke and other air pollutants.

A research paper from last year, which found a 7% increase in mortality among a cohort of older people living in southern California over a three year period due to wildfire smoke exposure, recommended that “activation of public health measures such as clean air centers should not only depend on intensity of smoke, as the long-term effects can be harmful, even at low levels.”

Lara Schwarz, an environmental health scientist at UC Berkley who led the research, said: “As wildfires become more frequent and severe in the context of climate change, with California being at high risk, understanding how these harmful wildfires will affect us in the long term is critical to informing better public health action and response.”