(NewsNation) — Underground bunkers are a staple feature of post-apocalyptic movies, and apparently they’re popular in real life, too.

Sales for private underground bunkers, or fallout shelters, increased this year, and they’re predicted to grow. The market was worth $137 million in 2023 and is projected to reach $175 million by 2030, according to Blue Weave Consulting, a data research company.

Experts point to the threat of nuclear or terrorist attacks and civil unrest as reasons for increased consumer demand. And with the demand, there are companies that meet the supply, driving overall market growth.

Ron Hubbard, CEO of Atlas Survival Shelters in Sulphur Springs, Texas, told the New York Post he saw a spike in calls after the invasion of Ukraine, and the interest hasn’t stopped.

COVID-19 and the war in Gaza are also concerns for some of the people buying private bunkers.

Bunk beds are seen inside an underground shelter in an undisclosed Southern California city, on Dec. 16, 2024. (AP Photo/Jae C. Hong)

Nuclear bunkers, which can sell for tens of thousands and even millions of dollars, are specifically made to protect against the blast and radiation from a nuclear explosion and are built of steel underground. The air filtration system is intended to reduce nuclear and biochemical exposure.

Some professionals warn bunkers give a false sense of security.

“Bunkers are, in fact, not a tool to survive a nuclear war, but a tool to allow a population to psychologically endure the possibility of a nuclear war,” said Alicia Sanders-Zakre, a policy and research coordinator at the International Campaign to Abolish Nuclear Weapons, to the Associated Press. “Ultimately, the only solution to protect populations from nuclear war is to eliminate nuclear weapons.”