Hello from life under the heat dome. Tens of millions of people across the United States, including here in New York City, are facing dangerous temperatures this week as a high-pressure system traps hot air around us.
Prolonged exposure to this stifling heat is dangerous on its own, but as Claire Brown and I reported today, heat waves also thicken and trap harmful pollution in the air we breathe. And President Trump’s rollbacks of clean air regulations threaten to make that cycle worse.
The dual hazards of extreme heat and air pollution on public health are becoming increasingly concerning as climate change pushes up global temperatures, researchers told us.
How air pollution harms health
Being exposed to high levels of heat or air pollution puts stress on the body, and when both happen at the same time, they “have an exaggerated harmful effect,” said Dr. Meredith McCormack, director of pulmonary and critical care at Johns Hopkins University. Health effects can add up the longer a heat wave continues and can lead to increased hospital admissions, experts said.
Air pollution affects the whole body, aggravating lung conditions like asthma and raising the risk of heart attacks and strokes. Children, older adults and people who have underlying conditions or are pregnant are at higher risk. Air pollution exposure is also associated with other illnesses like cancer, preterm birth and dementia.
Globally, air pollution leads to millions of premature deaths each year, and most of those deaths occur in low- and middle-income countries, according to the World Health Organization. In the United States, it leads to more than 100,000 premature deaths annually, according to the National Weather Service.
A recent report by the American Lung Association found nearly half of all Americans live in places with unhealthy levels of ozone or particle air pollution. People of color were more likely to live closer to pollution sources like power plants and highways, in part because of the history of racist practices like redlining.
There are two main types of air pollution that public researchers track: ground-level ozone and particulate matter. Ground-level ozone is a gas that forms from chemical reactions in sunlight, and burning fossil fuels contributes to its formation.
Particulate matter refers to tiny pieces of solids and liquids in the air. PM 2.5 particles, smaller than 2.5 micrometers in size, are the most dangerous of these because they can pass into the bloodstream.
How heat and air pollution are linked
Rising heat and worsening air pollution are closely connected. The burning of fossil fuels is both heating the planet and pumping out toxic air pollutants. And as climate change pushes global temperatures past record levels, the number of days when it is both hot and polluted has also increased.
Heat waves are primarily caused by high-pressure systems that push warm air down onto an area and hold it there. During heat waves, the air is stagnant, with little wind to blow away pollutant emissions from sources like vehicles or buildings. Sunny, hot conditions also encourage ozone to form faster. As a heat wave continues, pollution builds up.
Jim McQuaid, an atmospheric chemist at the University of Leeds, compared a heat wave to a “big cooking pot.” It holds in air pollutants and heat, making the air pollution inside “stronger and more potent” over time.
Climate change is also making wildfires more frequent and intense, and they produce smoke that can spread particle pollution for thousands of miles. Notably, in the summer of 2023, smoke from wildfires in Canada reached western Europe and the southern United States.
This week, multiple cities had heat warnings and forecasts of air quality levels that are unhealthy for sensitive groups, including New York City, Philadelphia, Cincinnati and Grand Rapids, Mich.
Tips for staying safe
Reducing health risks from air pollution, similar to the risks of heat, comes down to minimizing exposure, experts said. That starts with regularly checking air quality. Local weather reports often include air quality warnings in their forecasts. The E.P.A. also posts air quality information on its website, airnow.gov, although many areas lack official monitoring.
Experts suggest limiting time outside and avoiding exercising outdoors when air is unhealthy. In high-particle pollution events, like wildfires and smog, N-95 masks can provide some protection but won’t stop gases like ozone or the smallest particles.
The toll of time spent outside in extreme heat can add up quickly. When indoors, consider closing doors and windows on high pollution days if the temperature inside is comfortable, Dr. McCormack said, and use an air purifier. Many places, like New York City, open cooling centers during heat waves if you don’t have access to air-conditioning.
Claire Brown contributed reporting.
Climate policy
Trump administration to end protections for 58 million acres of national forests
The Trump administration said on Monday that it would open up 58 million acres of back country in national forests to road construction and development, removing protections that had been in place for a quarter century.
Agriculture Secretary Brooke Rollins announced plans to repeal the 2001 “roadless rule” that had preserved the wild nature of nearly a third of the land in national forests in the United States. Ms. Rollins said the regulation was outdated.
The unspoiled land in question includes Tongass National Forest in Alaska, North America’s largest temperate rainforest; Reddish Knob in the Shenandoah Mountains, one of the highest points in Virginia; and millions of acres of the Frank Church-River of No Return Wilderness in Idaho.
Environmental groups said the plan could destroy some of America’s untouched landscapes and promised to challenge it in court. — Lisa Friedman
Climate law
Oil companies fight climate lawsuits by citing free speech
Oil companies are employing an unusual tactic in some of their biggest court battles. They’re saying that their critics are infringing on their free-speech rights, invoking laws designed to protect people who challenge the powerful.
The laws, known as “anti-SLAPP” provisions, were created to stop companies or people from silencing their critics with the threat of costly lawsuits. Oil companies have turned this around, arguing that climate lawsuits against them should be thrown out because they infringe on the companies’ protections under the First Amendment.
“What we’re seeing now is a complete inversion” of the original intent of these laws, said Nicole Ligon, an assistant professor of law at Campbell University in North Carolina and expert on freedom of speech and SLAPP, which is shorthand for strategic lawsuit against public participation. — Karen Zraick
By the numbers
25 to 47 percent fewer plastic bags
At places throughout the United States where plastic bags require a fee or have been banned, fewer bags end up at the water’s edge, according to research published Thursday in Science.
Areas that adopted plastic bag policies saw a 25 to 47 percent reduction in the share of plastic bag litter on shorelines, when compared with areas without policies. The longer a policy was in place, the greater the reduction.
Using data compiled by the nonprofit Ocean Conservancy, researchers analyzed results from 45,067 shoreline cleanups from 2016 to 2023, along with a sample of 182 local and state policies enacted to regulate plastic shopping bags between 2017 and 2023. — Christina Kelso
More climate news from around the web:
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Companies in the United States canceled $1.4 billion in new factories and clean energy projects in May, according to an analysis by E2, an industry group.
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In a Times Opinion piece, Carl Pope, the former executive director of the Sierra Club, writes about the biggest mistake he made during 50 years of climate work: overlooking methane emissions.
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The Washington Post explores the surprising ways that food packaging can expose us to microplastics.
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Climate change is raising the risk of sleep apnea, according to a study highlighted by NPR. “The chance of having any kind of sleep apnea problem overnight goes up by almost 50 percent when it’s 80 degrees Fahrenheit or warmer, compared to when temperatures are in the 50s,” NPR writes.
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