When scientists turned on the instrument aboard a new satellite this summer, they got a preview of what will be the country’s first continuous record of air pollution.
The satellite will remain parked above North America and provide scientists with hourly daily updates on air pollution across the country. On Thursday, researchers released their first images, showing changes in nitrogen dioxide pollution in the United States over the course of a day.
“It’s really exciting to see the instrument working just as expected,” said Xiong Liu, the deputy mission director and a physicist at the Center for Astrophysics run by Harvard University and the Smithsonian Institution. The satellite instrument, called TEMPO, will also measure several other pollutants.
The images come during a summer of extremely poor air quality for the United States, with smoke from wildfires engulfing many cities and regions. But even before this summer, over the past decade or so, the gains in air quality that Americans have enjoyed since the passage of the Clean Air Act in 1970 started on the plateau.
While air pollution has improved over the years, “one-third of Americans still live with unhealthy levels of air pollution,” said Dr. Liu.
Nitrogen dioxide comes from burning fuel and creates other types of pollution through chemical reactions in the air. The images show clear gas hot spots around major cities, with higher levels in the morning and evening when there is more traffic.
In addition to peering at Earth through the new satellite, scientists have been scurrying across the country on foot and in research planes this July and August, in a tightly choreographed production to try to understand why the quality isn’t improving. of air
Because pollutants can quickly travel thousands of miles in the air, it has been difficult for scientists to pinpoint the largest sources of pollution on a national scale. TEMPO’s hourly updates are expected to be a “real game changer” in giving researchers the ability to track air pollution from its source, said Brian McDonald, an environmental engineer at the National Oceanic and Atmospheric Administration. who is coordinating field research this summer on the satellite .
Automobile traffic used to be one of the biggest contributors to air pollution, but stricter emission standards for motor vehicles have reduced pollution from driving. At the same time, the relative importance of consumer products and materials, such as paint and pesticides, that emit pollutants known as volatile organic compounds has increased, explained Dr. McDonald.
These compounds react with nitrogen dioxide in the air to create harmful ground-level ozone, which has remained stubborn in some areas, especially in California and major metropolitan areas across the country. While the ozone layer high in the atmosphere protects us from cancer-causing ultraviolet radiation, ozone near the ground can exacerbate or cause respiratory diseases such as asthma, bronchitis and emphysema.
Another persistent problem is fine particulate pollution, which is made up of microscopic particles small enough to enter the bloodstream and cause heart and lung disease, strokes and even premature death in severe cases. . This pollution, also known as PM2.5, began to rise again in 2016 after years of decline.
Wildfires, which are becoming more frequent and more intense as climate change creates hotter and drier conditions, appear to be the main culprit behind this reversal, according to a study published in last fall
That research relied on an older satellite that provided daily measurements, said Marshall Burke, a professor of environmental policy at Stanford University and one of the study’s authors. Currently, he and his colleagues rely heavily on computer models of how pollutants move with the air to fill in the blanks between actual observations.
Dr. Burke, who is not involved in the TEMPO mission, hopes to have hourly data from the satellite, which will be “closer to a video,” he said. “As you have more images, it’s easier to fill in the map of where things came from,” he added.
TEMPO will be able to monitor air pollution down to a resolution of about four square miles. That’s where bundled flights, trips, and hikes come in this summer.
“The data from these field campaigns acts like a decoder ring” for the satellite instrument, said Tracey Holloway, a professor of energy analysis and policy at the University of Wisconsin-Madison who studies air quality but not involved in this project.
One of the places where scientists are collecting data at the local level is New York City. Even cities that regularly monitor their air usually don’t have enough equipment to cover all neighborhoods. That’s a problem because within individual cities or regions, air pollution tends to be unevenly distributed.
Since late July, a dozen researchers led by NOAA’s Audrey Gaudel and Prathap Ramamurthy have taken turns walking in pairs around the city, carrying backpacks filled with buzzing air quality sensors. Onlookers often ask if the scientists are fishing, because of the long, thin tubes that stick out of the pack to suck air samples.
Every day, a colleague tracks the flight paths of NASA research aircraft and provides updates on WhatsApp so that trekkers can walk under the planes. Data sets will be compared later. The researchers covered a dozen routes, making sure to include economically disadvantaged neighborhoods and neighborhoods with more residents of color. These areas often face disproportionate air pollution, but data is sparse.
“We hope to have better models and better street-level predictions,” said Yoshira Ornelas Van Horne, a professor of environmental health at Columbia University and another TEMPO collaborator.
It will take months to analyze all the data, but the walks themselves have already highlighted the connection between climate change and air quality. (Dr. Ramamurthy says some of the hourly walks in the height of summer are “terrible.”) Higher temperatures are generally associated with higher levels of ozone pollution, and the hottest sampling day, ozone readings rose above national standards set by the Environmental Protection Agency, said Dr. Gaudel.
Data from the TEMPO satellite should be available to the general public in spring 2024. So far, more than 400 users, including many state and federal agencies, have signed up as “early adopters.”
Researchers at Mount Sinai Health System in New York plan to use TEMPO data to study how air pollutants affect children’s asthma symptoms. The Connecticut Bureau of Air Management plans to use the data to investigate where the state’s unusually high ozone pollution is coming from.
Dr. Ornelas Van Horne hopes research this summer will give policymakers the information they need to do something about the nation’s lingering air quality problems. “We all agree that air pollution is bad,” he said.
