Episode #56 2025 State of the Air: Dangers of the Air We Breathe with Dr. George Thurston

Dr. Albert Rizzo:
Welcome back to Lungcast, the monthly respiratory health podcast series from the American Lung Association and medical news site hcpive.com. I'm your host, Dr. Albert Rizzo, chief medical officer of the American Lung Association.

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The United States Clean Air Act passed in 1970 and was strengthened with subsequent amendments in 1990. It's a comprehensive federal law that regulates all sources of air emissions. The 1970 act authorized the US Environmental Protection Agency, or EPA, to establish national ambient air quality standards, or NAAQS, for six criteria air pollutants in order to protect public health and the environment. Ground-level ozone and particulate matter are two of the six, and we will be discussing them today. For your information, the others include carbon monoxide, sulfur and nitrogen dioxide, and lead.

This podcast is a special edition related to the American Lung Association's yearly State of the Air report. The American Lung Association releases this report as an annual air quality report card that tracks individuals’ exposures in cities nationwide to unhealthy levels of ground-level ozone, or smog, and particle pollution, or soot, over the course of a three-year time frame. The report also publishes a ranking of the most polluted and cleanest U.S. cities for air quality.

Our guest today is Dr. George Thurston, who has a nationally and internationally recognized record of multidisciplinary academic training and expertise in air quality, epidemiology, and exposure assessment. He is currently a tenured member of the faculty of the departments of medicine and population health at New York University's Grossman School of Medicine, where he directs the graduate program in human exposure and health effects. He received his doctorate in environmental health sciences from the Harvard School of Public Health, where his research was part of the landmark Harvard Six Cities air pollution study.

He has also been an active volunteer adviser on air quality for the American Lung Association, and we thank him for that.

Dr. Thurston, thank you for being with us today and spending your time and effort with us, especially as we start to talk about the State of the Air Report 2025.

Dr. George Thurston:
Great to be here with you.

Dr. Albert Rizzo:
So, just for a little background for our listeners, the State of the Air Report uses the most recent quality-assured air pollution data from county measuring stations collected by official federal, state, local, and tribal governments in the years 2021, 2022, and 2023. The year delay in reporting is necessary to allow for collection of accurate and validated data from these various agencies.

The measures are for ozone and two particle pollution measures—one for short-term and one for annual exposure. Regrettably, county measuring stations for the data we are reporting are present in only about 922 of the over 3,000 counties in the United States. That means there are more than 72 million people who live in counties where their ozone and particle pollution levels are not being monitored. And as we will discuss, that can have health consequences.

According to this year's report, nearly half of the people living in the U.S. breathe unhealthy levels of air pollution. Extreme heat and wildfires contributed to worse air quality for millions of people across the U.S. Particle pollution continued its decade-long worsening trend, and unhealthy levels of ozone pollution impacted significantly more people compared to our recent reports.

This year's report found that nearly half, or 46%, of the people in the United States live in an area that received a failing grade for at least one measure of air pollution—that’s 156 million people in total. 42.5 million people live in areas with a failing grade for all three measures.

This year, there are only two cities, Bangor, Maine, and San Juan, Puerto Rico, that made the cleanest cities list for all three pollution measures. Last year, there were five cities on that list.

Per this year's report, deadly particle pollution continues to impact communities in many parts of the country. 77 million people live in counties that experience unhealthy spikes in particle pollution. This is the highest figure in the last 16 years of this report. Particle pollution, which we measure as PM2.5, can have numerous health effects when inhaled. There is a measure for both short-term and annual, or year-round, particle pollution.

Dr. Thurston, please explain why a short-term and annual particle exposure measure are important, and describe some of the health effects of these exposures, as well as which populations seem to be most at risk.

Dr. George Thurston:
Yes, both short-term standards, in other words, looking at acute effects of air pollution exposure over short periods of time, and the cumulative effects of exposure day after day, are important. And then there are the long-term standards.

For example, with short-term standards, children with asthma will react to the pollution it causes. Fine particles and ozone can cause inflammation in their lungs, which can lead to exacerbation of asthma and the need to use rescue medications.

In the longer term, it can actually lead to the development of new disease. For example, the Children's Health Study in California found that children living near trafficked areas with higher nitrogen oxides, ozone, and fine particles had a higher rate of developing asthma.

So, there are both long-term cumulative effects of creating new disease and acute effects of worsening and exacerbating disease in the short term. The long-term effects of pollution are more than just the sum of short-term effects—they’re actually quite different.

For cardiovascular effects, short-term exposures to fine particulate matter, especially urban particles with high sulfur and transition metal content, can increase the risk of heart attack in people who already have cardiovascular disease. Over the long term, day-to-day cumulative exposure increases atherosclerosis and plaque buildup, leading to long-term risk. So, acute effects are short-term but can be severe, while long-term exposure creates new risks.

Dr. Albert Rizzo:
Great. This year's report also includes data from the summer of 2023, when Canadian wildfire smoke significantly impacted the Midwest and eastern states, resulting in worse particle pollution.

Dr. Thurston, can you comment on the effects that wildfires have on air quality, and whether there’s a distinction between wildfire-related air quality issues and non-wildfire air quality issues?

Dr. George Thurston:
Yes, wildfires are a very serious concern. They indicate that our climate is changing, and we’re seeing more of them every year. Firefighters get large exposures, which is an occupational risk, and the general public is exposed to biomass particle pollution.

For example, during a study in New York City, we saw a spike in asthma and chronic obstructive pulmonary disease emergency room visits when wildfires occurred. These respiratory effects are very irritating and can exacerbate disease. Longer-term exposure to organic materials and hydrocarbons from wildfire smoke can even contribute to lung disease and lung cancer.

There’s also a difference between wildfire pollution and urban pollution. Urban air pollution, from fossil fuel combustion—traffic, diesel trucks, cars, heating—is high in sulfur and transition metals. These components tend to affect the cardiovascular system more severely. Wildfire pollution, while still harmful, lacks many of the toxic compounds found in fossil fuel combustion. So, both are health concerns, but their nature and effects differ.

When wildfires encroach on cities, the effects compound with existing urban pollution, creating a “double whammy.” Ambient urban pollution is insidious—people are exposed day and night, and even low levels can accumulate to cause severe health outcomes over time.

Dr. Albert Rizzo:
Thank you. You mentioned particle pollution, and now let's talk about ozone.

Dr. George Thurston:
Ground-level ozone is a powerful respiratory irritant, often described as a “sunburn of the lungs.” Warmer temperatures increase ozone formation, and cleanup is difficult. Some communities are seeing the worst ozone levels in years. More than 125 million people, or 37% of the nation, lived in areas with unhealthy ozone pollution—an increase of 24.6 million people from last year’s report.

Ozone is a secondary pollutant—it doesn’t come directly from exhaust but forms in the atmosphere from hydrocarbons and nitrogen oxides in the presence of sunlight. It is highly reactive.

If it oxidizes rubber, imagine what it does to lungs. When inhaled, it causes inflammation. Children with asthma are particularly vulnerable, as inflammation increases sensitivity to allergens and can trigger asthma attacks.

At an American Lung Association summer camp in Connecticut, downwind of New York City and the Midwest, high ozone levels coincided with more asthma exacerbations in children. Care at the camp prevented ER visits, but the impact of ozone was clear.

Dr. Albert Rizzo:
What measures can individuals and organizations take to reduce particle pollution and ozone?

Dr. George Thurston:
We need to maintain high air quality standards and prevent any weakening of the Clean Air Act protections. Beyond that, standards should be re-evaluated and tightened as evidence shows that even low levels of pollution have health effects. There’s no absolute threshold below which pollution is harmless. Progress is gradual, but cleaner air over time allows us to see the effects at lower exposure levels.

Dr. Albert Rizzo:
For listeners, the full State of the Air Report can be viewed and downloaded at lung.org.

Spoiler alert: The three most polluted cities for short-term particle pollution were Bakersfield, California; Fairbanks, Alaska; and Eugene, Oregon. The three most polluted cities for year-round particle pollution were Bakersfield, Baselia, California, and Fresno, California. The three most polluted areas for ozone were all in California: Los Angeles, Vaselia, and Bakersfield. Only two cities, Bangor, Maine, and San Juan, Puerto Rico, made the cleanest cities list for all three pollution measures.

Dr. George Thurston:
California actually has two worlds in terms of air quality. Coastal cities like Santa Barbara, Salinas, and San Luis Obispo are among the cleanest, while the Central Valley and Los Angeles have poor pollution dispersion. California needs to set its own standards to protect residents effectively.

Dr. Albert Rizzo:
Thank you again for your time today and for your volunteer work with the American Lung Association. For our listeners, Lungcast has an archive of discussions with experts on indoor air quality and past State of the Air reports. A full list is available at lung.org/lungcast.

Be sure to subscribe and rate Lungcast on your preferred platform, and visit lung.org and hcpive.com for more news and resources.

Until next time, I’m Dr. Albert Rizzo reminding you that if you can't breathe, nothing else matters.