Scientists activated a new satellite instrument this summer, offering a glimpse of what will soon become the nation’s inaugural continuous air pollution record. Positioned above North America, the satellite is set to provide scientists with hourly updates on nationwide air pollution during daylight hours. Initial images released by researchers reveal shifts in nitrogen dioxide pollution across the United States within a day.
“It’s truly thrilling to witness the instrument performing as anticipated,” said Xiong Liu, the deputy mission director at the Center for Astrophysics managed by Harvard University and the Smithsonian Institution. Named TEMPO, the satellite instrument is designed to measure several other pollutants as well.
These images coincide with a summer marked by notably poor air quality in the United States due to wildfire smoke enveloping various cities and regions. Even prior to this summer, the gains made in American air quality since the implementation of the Clean Air Act in 1970 had shown signs of leveling off.
Though air quality has improved over time, Dr. Liu notes that “one-third of Americans still reside in areas with unhealthy air pollution levels.”
Nitrogen dioxide originates from fuel combustion and contributes to other forms of pollution through airborne chemical reactions. The images demonstrate distinct nitrogen dioxide concentrations around major urban centers, with higher levels during peak traffic periods in the morning and evening.
In addition to monitoring Earth from the new satellite, scientists embarked on field research nationwide this July and August. This comprehensive effort seeks to explain the halt in air quality enhancement. Given that pollutants can travel extensive distances on air currents, pinpointing the primary sources of pollution on a national scale has proven difficult. TEMPO’s projected hourly updates are anticipated to be transformative, enabling researchers to trace air pollution back to its origins.
Historically, vehicular traffic has been a leading source of air pollution, but stricter vehicle emission standards have curtailed driving-related pollution. Simultaneously, the significance of consumer products and materials such as paint and pesticides, which emit volatile organic compounds (VOCs), has grown. VOCs combine with nitrogen dioxide to produce harmful ground-level ozone, which remains stubbornly elevated in certain regions, notably in California and major metropolitan areas across the country.
Another persistent challenge is fine particulate pollution, composed of minuscule particles capable of entering the bloodstream and causing heart and lung diseases, strokes, and even premature death in severe instances. This type of pollution, known as PM2.5, began rising again around 2016 after a period of decline. Wildfires, increasingly frequent and intense due to climate change-driven hotter and drier conditions, are believed to be the primary cause of this reversal, according to a study published last fall.
However, that study relied on an older satellite that offers daily measurements. Researchers rely heavily on computer models to fill gaps between actual observations, making TEMPO’s hourly data highly anticipated.
TEMPO’s resolution is capable of tracking air pollution down to approximately four square miles. To complement this, this summer’s coordinated on-the-ground efforts come into play.
Data gathered during these localized efforts is particularly detailed in places such as New York City. Even cities with consistent air monitoring often lack adequate equipment coverage for all neighborhoods, a concern due to uneven distribution of air pollution within cities or regions.
Since late July, a team led by researchers Audrey Gaudel and Prathap Ramamurthy of the National Oceanic and Atmospheric Administration (NOAA) has roamed New York City in pairs, each carrying a backpack laden with buzzing air quality sensors. Passersby frequently mistake them for anglers due to the long tubes extending from their packs to collect air samples. One team member monitored NASA’s research aircraft flight paths and relayed updates via WhatsApp to the walkers below.
Analysis of the collected data will take several months. Yet, these endeavors have already illuminated the connection between climate change and air quality. Higher temperatures generally correlate with increased ozone pollution levels, and on the hottest day, ozone readings exceeded national standards set by the Environmental Protection Agency.
TEMPO’s satellite data will be accessible to the public in spring 2024. In the meantime, more than 400 users, including state and federal agencies, have signed on as “early adopters.”
Mount Sinai Health System researchers in New York intend to leverage TEMPO data for studying the impact of air pollutants on children’s asthma symptoms. The Connecticut Bureau of Air Management will utilize the data to investigate the origins of the state’s disproportionately high ozone pollution.
Dr. Ornelas Van Horne aspires for this summer’s research to equip policymakers with insights to address the nation’s ongoing air quality concerns. “We all agree that air pollution is harmful,” she emphasized.