Tuesday, September 30, 2025

Frequent wildfires, heat intensify air quality issues in American megacities such as New York City

Emerging global drivers of urban aerosol pollution are combining to create a new set of challenges for public health officials tasked with protecting millions of people on the East Coast

Colorado State University

Air tower — image:
View of the FROG flux tower which has sampling equipment used in the study on it. Credit: Emily Franklin/Colorado State University
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Credit: Credit: Emily Franklin/Colorado State University

Air quality in America’s largest cities has steadily improved thanks to tighter regulations on key sources of particulate pollution. However, increased heat, wildfire smoke and other emerging global drivers of urban aerosol pollution are now combining to create a new set of challenges for public health officials tasked with protecting millions of people on the East Coast.

Research from Colorado State University published in npj Climate and Atmospheric Science begins to unpack and characterize these developing relationships against the backdrop of New York City. The research quantifies how existing particulate pollution from sources such as vehicle exhaust or consumer products are now combining with wildfire smoke –– transported from thousands of miles away –– to create secondary, often more toxic, pollution or contribute to the formation of ozone in hot weather.

Professor Delphine Farmer in the Department of Chemistry led the research with data collected from continuous on-the-ground readings at a site on Long Island during the summer of 2023.

“We did not set out to study air quality, wildfire and heat in that way, but smoke from fires in Canada arrived and, unfortunately, that is likely to be more and more common in the future,” Farmer said. “Cities on the West Coast have been dealing with these combined issues for a while, but the developing situation in New York is a good test case to understand how variables like the nearby natural forests and denser populations on the East Coast may contribute to these emerging drivers of air pollution in mega cities.”

Aerosol pollution consists of tiny particles of smoke or other compounds from many common sources such as cleaning solutions or cooking in restaurants. It can also occur naturally from the gases plants release every day. Hotter temperatures can cause plants to release more of those gases and speed the evaporation of some of those consumer products into particulate air pollution. Meanwhile, wildfire smoke particles absorb and react to those same gasses –– further amplifying both natural and man-made sources of pollution. Because these particles can enter the lungs, they may lead to heart disease, cancer and even dementia, making them a key focus area for health regulation.

Farmer said the situation in New York presented an opportunity to start to untangle the relationships between sources and their impacts overall. Her team found evidence that 90 percent of the aerosol pollution found over the city was indeed sensitive to at least one aspect of these global changes, such as high temperatures –– meaning effects from the pollutants were made worse during a heat wave, for example.

Some volatile chemical products such as paints and solvents are sensitive to these changes, and the team’s work shows that those sources are responsible for more than double the estimated contribution from cars to the city’s air pollution total in this category.

New York also has plenty of restaurants where the daily cooking and cleaning activities can contribute to overall pollution totals as well. However, the team found that while those emissions were also sensitive to the introduction of smoke or higher temperatures the effects were localized.

“We found that restaurants do have a big impact on their own local neighborhoods, but their associated aerosols are only a minor component of the total average load across the region,” Farmer said. “Still, any worsening of those conditions from the arrival of wildfire smoke –– for example –– could lead to environmental health inequality for those areas that health policy makers will need to consider.”

She added that context like that will help policy makers prioritize sources of pollution to target for both their overall contributions to the area’s air quality and their localized impact on public health.

Machine learning techniques aid research into urban air pollution

Emily Franklin led aerosol data collection on the ground and follow-up analysis for the project as a CSU postdoctoral fellow funded by the National Science Foundation. She has since taken a position as a research scientist at CSIRO, Australia’s national science agency.

Franklin said the team pulled measurements from many different instruments on the site and worked closely with fellow researchers from the universities of Minnesota, Columbia, Michigan and the University of California, Berkeley for the project. Together, these instruments generated thousands of individual indicators of aerosol composition, including characterization of hundreds of unique but unidentifiable compounds in the atmosphere. To take advantage of these complex measurements, she leveraged machine learning techniques.

“This was an incredibly rich and complex dataset. In a place like New York, you have compounds coming from trees in city parks, fires in Canada, construction sites miles away, and the barbecue joint up the road,” Franklin said. “Machine learning was a powerful tool allowing us to embrace this complexity and leverage it to better understand how all of these sources interact with the climate to make the air pollution experienced by the community.”

Funding for this project came from the National Oceanic and Atmospheric Administration as part of their AGES+ campaign, which is focused on improving air quality understanding through extensive, coast-to-coast observation using ground sites, research aircraft and satellite data.

The CSU team will now continue to study air quality in the region through the NSF funded GOTHAAM Campaign using a C-130 aircraft as a flying chemistry lab to measure atmospheric composition in real time across New York, New Jersey and Connecticut. That project focuses on volatile organic compounds –– a broad term for gases from car exhaust, industry, vegetation and consumer products that react in the atmosphere to form ground-level ozone, secondary organic aerosols and particulate matter.

Farmer said measurements taken from the plane will give the team a better sense of the chemistry happening in the region as they will be able to get readings over the ocean and at different altitudes. Ideally, they will be able to provide more information to the millions of residents in the broader region about their air quality and potential health risks from it.

“We worry about what we are breathing on the ground but in reality, the chemistry happening above us has a big impact on that. This research project will again help us understand key interactions better and improve our ability to predict potentially hazardous air quality conditions,” she said.

Caption
Emily Franklin collecting samples at the train station. Credit: Trey Maddaleno
Credit
Credit: Trey Maddaleno

Journal

npj Climate and Atmospheric Science

DOI

10.1038/s41612-025-01202-w

Article Title

Emerging Drivers of Urban Aerosol Increase Global Change Vulnerability in a US Megacity

Article Publication Date

30-Sep-2025

FUSION: SCI-FI-TEK 70 YRS IN THE MAKING

Lightning strikes 12 times per minute on Zap Energy’s century platform

Achievement of 39 kilowatt average power operations marks twenty-fold progress in enabling technologies for Z-pinch fusion power plant

Zap Energy

Project Century — image:
Century is Zap Energy's fusion engineering test platform.
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Credit: Zap Energy

EVERETT, Wash. - Zap Energy has advanced its Century fusion engineering test platform to operate for more than one hundred plasma shots at 0.2 Hz, or one shot every five seconds, with the resulting heat captured by surfaces coated with circulating liquid metal. Concentrated inside a vacuum chamber about the size of a hot water heater, each plasma carried up to 500 kA of current — about 20 times stronger than a bolt of lightning — discharged into a vessel lined with flowing liquid bismuth. During the record run, Century’s total input power was 57 kilowatts, with 39 kilowatts delivered directly to the cables leading to the plasma chamber.

Compared with Century’s commissioning milestone in 2024, this achievement represents a 20x increase in sustained average power and is a major step toward developing commercial fusion power plants using repetitive pulsed power and liquid metal energy transfer.

Integrating fusion plant technologies

Century replicates the commercial engineering conditions of Zap’s unique approach to fusion, which doesn’t rely on superconducting magnets or high-intensity lasers. Instead, Zap’s sheared-flow-stabilized (SFS) Z-pinch fusion modules drive a pulse of electricity through a flowing plasma stream, generating a magnetic field that compresses the plasma, as well as stabilizing forces that sustain it.

“Prolonged operations of a fully integrated, repetitively pulsed system at 30 kilowatts gives us a much clearer picture of what a sheared-flow Z-pinch fusion power plant will actually look like,” said Matthew Thompson, VP of Systems Engineering at Zap Energy. “Century’s real-world tests of our engineering subsystems mean we’ve already begun to identify and solve many of the most difficult commercial technology challenges.”

One of Century’s goals is to characterize energy transfer between three key power plant subsystems: repetitive pulsed power (frequent bursts of energy), liquid metal walls (for absorbing and transferring fusion energy out of the plasma chamber) and durable electrodes (components capable of surviving extreme conditions). These technologies are essential to building a commercial fusion system that will steadily generate energy over a sustained period.

Since first operations last year, each of Century’s subsystems has been upgraded with the goal of reaching the 30 kW milestone. Upgrades include:

A liquid metal loop circulating 2,500 pounds (1,100 kilograms) of flowing bismuth. The liquid bismuth acts as an electrical conduction path, a plasma-facing protective barrier, and a heat transfer fluid.
A liquid metal first wall using centrifugal forces to cover more exposed solid metal surfaces, improving its ability to absorb plasma heat.
A custom-built 200-kilowatt air-cooled heat exchanger that helps maintain thermal equilibrium.
A redesigned nose cone, tipped with liquid metal to prevent cathode erosion.
A high-flow cathode surge cooling system that helps quickly reduce system temperature between shots.

“Century is maturing technologies that will ultimately convert energy from our fusion reactions into electricity or industrial heat—systems engineering has historically been overlooked in fusion development,” said Benj Conway, CEO and co-founder of Zap Energy. “Fusion is not just a plasma problem. It’s a systems integration problem.”

How Century works

Each Century shot begins in its power banks: a set of large-scale capacitors pulls energy from the grid, stores it briefly, and then releases a short burst of current into the top of Century’s vacuum chamber via heavy-gauge cabling. Inside the vertically-oriented plasma chamber, modeled after a Zap FuZE device, the pulse ionizes a puff of hydrogen gas into an extremely hot, dense filament of plasma. (Because its design objective is engineering validation, Century operates with plain hydrogen or helium gas, rather than fusion-grade deuterium-tritium fuel. As a result, its plasmas do not undergo fusion reactions or emit neutrons.)

Finally, thermal energy from the plasma reaches the flowing liquid metal wall that coats the plasma chamber inner surface. The circulating metal absorbs the plasma’s thermal energy, transfers it to an air-cooled heat exchanger, and then returns to the vacuum chamber.

Scaling up Since its commissioning in June 2024, Century has increased its capacity from single plasma shots every 10 seconds at ~1.4 kilowatt of average power, to one shot every five seconds, at ~30 kilowatts of average power. In February 2025, the DOE certified the completion of a three-hour Century campaign producing more than one thousand consecutive plasma shots, each with at least 100 kiloamps of current. In the past year, the platform has fired more than ten thousand shots across a wide range of configurations, providing valuable lessons about how to operate high-repetition-rate Z-pinch plasmas.

Earlier this month, Fusion Science and Technology published a paper on Century’s design and its commissioning runs between June and October 2024. Over the coming months, Zap will continue to investigate critical technical questions while gradually ramping up Century’s repetition rate and power levels.

Century generates sheared-flow-stabilized Z pinch plasmas inside this vacuum chamber that carry electrical current stronger than a bolt of lightning. The system is repetitively pulsed at a rate of up to one plasma every five seconds for hundreds of shots in a row.

**Swirling liquid metal wall [VIDEO]**
Zap Energy is testing a prototype liquid metal first wall for fusion that uses centrifugal forces to cover exposed solid metal surfaces. Part of its Century platform, liquid metal walls are considered a critical technology for survivable surfaces and energy transfer inside fusion devices.
Credit
Zap Energy