After the Fact

How can what's happening in the ocean directly affect the environment, the food we eat, and our health? In this episode, the "After the Fact" team travels to San Francisco to hear about harmful algal blooms (or "red tides"), which occur when certain algae grow out of control and create dangerous toxins. The effects of these blooms can harm the health of humans and marine life and affect the livelihoods of people living in coastal communities. Matthew Gribble — an environmental health scientist at the University of California, San Francisco — dives into the research behind these harmful algal blooms and shares ways that the health of people, wildlife, and the ocean are all interconnected. We also hear from a fisher about how the red tides can shorten or delay the fishing season, as well as people who rescue marine mammals that have been poisoned by these toxins.

Americans' views of religion have been changing for decades. And in 2026, the share of people who identify as "religious nones" (people who say they have no religious affiliation) is holding steady at 28%. This episode, originally released in 2019, focuses on the shifts in perspectives across generations and the nation's changing religious landscape.

The fertility rate in the U.S. hit another record low in 2025, with 20% fewer babies born that year compared to 20 years ago, indicating that women are continuing to wait longer to have children. This was a growing trend when this episode originally aired in 2019, where a Pew researcher explains the data behind this change in the American family and two mothers share why they waited to have children.

Nearly 800 million people around the world live within 62 miles of a volcano. But what if scientists could better predict a volcanic eruption before it begins? In this re-release from our "Scientists at Work" series, originally published in 2020, we go behind the scenes at the Smithsonian National Museum of Natural History to talk with geologist and volcanologist Ben Andrews. His job is to answer three key questions about volcanoes around the world: When will an eruption happen, how big could the eruption be, and how fast?

This summer, we're revisiting the ways that scientists are using artificial intelligence in their health research. Keyla Sá, a researcher at Yale University School of Medicine, discusses her work tracking how long COVID develops and an AI tool that can identify its wide variety of symptoms and patterns. Since this episode originally aired in 2024, researchers are still learning about the ways long COVID continues to affect millions of people.