PULSE POINTS:
What Happened: The Trump-led EPA has launched an investigation into Make Sunsets, a solar geoengineering startup, for releasing sulfur dioxide into the atmosphere, prompting concerns about air quality violations under the Clean Air Act.
Who’s Involved: EPA Administrator Lee Zeldin, Make Sunsets founders Luke Iseman and Andrew Song, and the EPA’s Office of Air and Radiation.
Where & When: EPA Headquarters, Washington, D.C., April 14, 2025, with a public statement from Zeldin on April 15, 2025.
Key Quote: EPA Administrator Lee Zeldin stated on X, “Make Sunsets is a startup that is geoengineering by injecting sulfur dioxide into the sky and then selling ‘cooling credits.’ This company is polluting the air we breathe.”
Impact: The EPA’s actions could lead to monetary penalties or criminal charges for Make Sunsets, potentially setting a precedent for regulating geoengineering activities in the U.S., amidst broader Trump administration efforts to deregulate climate policies.
IN FULL:
The U.S. Environmental Protection Agency (EPA), under the leadership of President Donald J. Trump’s Administrator Lee Zeldin, has initiated what it says will be a swift investigation into Make Sunsets, a startup accused of polluting the atmosphere through geoengineering. On April 14, 2025, the EPA’s Office of Air and Radiation issued a letter to Make Sunsets founders Luke Iseman and Andrew Song, demanding information within 30 days to determine if the company’s activities violate the Clean Air Act.
Make Sunsets has been releasing sulfur dioxide into the stratosphere via weather balloons, aiming to reflect sunlight and cool the planet—selling these balloon flights online in the form of so-called “cooling credits.” The Trump administration is acting against the startup due to its potential to degrade air quality, coupled with a lack of regulatory oversight.
Zeldin took to X (formerly Twitter) on April 15, 2025, to explain the situation, stating, “Make Sunsets is a startup that is geoengineering by injecting sulfur dioxide into the sky and then selling ‘cooling credits.’ This company is polluting the air we breathe. I’ve instructed my team that we need to quickly get to the bottom of this.”
The EPA’s letter, signed by Abigale Tardif, Principal Deputy Assistant Administrator of the Office of Air and Radiation, cites Section 114(a) of the Clean Air Act, which empowers the agency to demand information from entities suspected of impacting air quality. It warns of potential enforcement actions under Section 113 of the Act, which includes fines and criminal penalties for non-compliance or providing false information.
On behalf of Make Sunsets, Iseman previously argued, “It’s morally wrong… for us not to be doing this.” However, the company has already been banned in Mexico following unauthorized sulfur dioxide releases in Baja California in 2022. Notably, this prompted the Mexican government to prohibit solar geoengineering experiments altogether in 2023.
Make Sunsets later conducted launches in Nevada, which also drew scrutiny for failing to report to the National Oceanic and Atmospheric Administration (NOAA) despite requirements under U.S. law. Critics, including environmentalists and scientists, have long warned that such geoengineering efforts lack sufficient scientific backing and international governance, posing unpredictable risks to the environment and public health.
The investigation into Make Sunsets could set a significant precedent for regulating geoengineering in the U.S., a field that remains largely ungoverned both domestically and internationally.
READ:
Make Sunsets is a startup that is geoengineering by injecting sulfur dioxide into the sky and then selling “cooling credits.” This company is polluting the air we breathe. I’ve instructed my team that we need to quickly get to the bottom of this and take immediate action. pic.twitter.com/9b6xPzMf4v
— Lee Zeldin (@epaleezeldin) April 15, 2025