Wildfire smoke is becoming an increasing threat to pregnant women as climate change drives more frequent and intense fires, potentially undermining improvements made in air quality through reductions in pollution from transport and industry.

A new study published in Frontiers in Environmental Health examined exposure to fine particulate matter, known as PM2.5, from wildfires across the United States between 2003 and 2019. Researchers found that prenatal exposure to wildfire smoke more than doubled during the 17-year period.

The increase was particularly significant in western US states, where wildfire seasons have become longer and fires have grown more severe. Researchers found that wildfire smoke was responsible for about 65% of days when air pollution reached levels considered unsafe during pregnancy.

The findings suggest that progress in reducing pollution from human activities is being partly offset by emissions from wildfires.

“Increasing wildfire activity is systematically offsetting prenatal air quality gains,” researchers said, warning that the trend could place a disproportionate burden on low-income, rural and Indigenous communities as wildfire activity continues to intensify.

PM2.5 consists of microscopic particles that can travel deep into the lungs and enter the bloodstream. Exposure during pregnancy has previously been associated with health problems including premature birth and low birth weight.

Researchers also noted that particles produced by wildfires may pose additional risks because their chemical composition can differ from pollution produced by traffic and industrial activity. This could make wildfire smoke particularly concerning for people who are more vulnerable to air pollution.

The findings have implications beyond the United States, as Europe has also experienced increasingly severe wildfire seasons in recent years.

Countries including Greece, Portugal, Spain and France have faced major fires during successive summers, with smoke sometimes spreading across national borders. European climate and health authorities have warned that rising temperatures are contributing to conditions that increase the likelihood and intensity of wildfires.

The growing exposure has raised concerns about how public health systems can protect vulnerable groups as climate-related risks increase.

Experts say governments may need to strengthen guidance for pregnant women and other groups at higher risk from smoke exposure. Measures could include improved wildfire smoke forecasting, earlier health warnings and greater access to clean indoor air during periods of severe pollution.

The research highlights a challenge facing environmental policymakers. While decades of measures have reduced pollution from vehicles, industry and other human activities, climate change is creating additional sources of harmful air pollution.

Good sleep may have a stronger influence on teenagers’ academic performance and social lives than diet, exercise or screen time, according to new research examining the daily factors that shape young people’s well-being.

The findings suggest that sleep could be particularly important for children experiencing symptoms of depression, anxiety or psychotic-like experiences, which have been linked to difficulties at school and in relationships.

Researchers examined data from more than 6,000 children for academic performance and more than 7,000 for social difficulties. The participants were aged between 10 and 13 and were assessed on four lifestyle factors: sleep quality, screen use, physical activity and diet.

Children showing symptoms of mental health difficulties generally performed worse academically and experienced more social problems. However, researchers found that lifestyle habits appeared to explain a significant part of this relationship, with sleep standing out as the most important factor.

“We expected sleep to be important, but we didn’t expect it to stand out so clearly above other lifestyle factors, particularly screen time,” said Jason Smucny, the study’s lead author at the University of California, Davis.

Researchers said poor sleep can cause daytime tiredness, problems with concentration and weaker executive functioning, all of which can make it harder for students to learn, complete schoolwork and perform well in examinations.

Sleep may also affect relationships. Disrupted or inadequate sleep can contribute to irritability and social withdrawal, potentially making it harder for young people to communicate with friends and maintain healthy relationships.

The researchers said their findings point to sleep quality as an important pathway through which early mental health symptoms can affect everyday functioning.

Tara Niendam, the study’s senior author, said parents, teachers and health professionals often concentrate on symptoms such as anxiety and depression, but families are also concerned about how those difficulties affect school performance, friendships and daily activities.

The research suggests that improving sleep routines could be one practical way of supporting young people facing these challenges.

Adolescents have increasingly struggled to get enough sleep, with previous research indicating that teenage sleep levels have declined over recent decades. School demands, social activities, technology use and changing schedules can all interfere with regular sleeping patterns.

The researchers stressed that better sleep cannot address every mental health problem. However, establishing consistent sleep routines may support emotional health and help young people manage the demands of school and social life.

With summer giving students an opportunity to recover from demanding school schedules, the findings highlight the potential importance of using the break to establish healthier and more consistent sleeping habits before the new academic year begins.