The Belize National Forensics Science Service executive director, Gian Cho, said Thursday that carbon monoxide poisoning killed three American women found dead while at a vacation resort there in February.

Merely having a carbon monoxide detector is not enough if they aren’t tested regularly and replaced every few years, Charon warned

Arar, 26 — all from Revere, Mass. — were found dead inside their room at the Royal Kahal Beach Resort in San Pedro on Feb. 22.

Carbon monoxide poisoning is a danger travelers need to be well aware of. Here's what you need to know to protect yourself.

Officials told the families of three Revere women who were found dead in Belize what caused the “acute pulmonary edema” that killed them.

Carbon monoxide is an odorless, colorless gas that takes hundreds of lives each year, and makes even more people sick.

Miller Gardner, the youngest son of former New York Yankees outfielder Brett Gardner, died March 21​ at the age of 14 while on vacation with his family.

A cause of death has been determined for three young women from the United States found dead in their hotel room at a resort in San Pedro, Belize, late last month, NBC News reported.

The women’s families issued a statement saying they had been notified by officials in the Central American country Wednesday who told them the women died from “acute” carbon monoxide poisoning, likely from an instant hot water heater.