Carbon monoxide, often called the “silent killer,” has no taste, odor or color, yet prolonged inhalation of the invisible gas has been linked to the recent deaths of several American tourists traveling abroad.

Miller Gardner, the 14-year-old son of the retired Yankees player Brett Gardner, died from carbon monoxide poisoning while on vacation in Costa Rica. Here’s why the gas is so dangerous.

Miller Gardner -- the 14-year-old son of former New York Yankees outfielder Brett Gardner -- died from carbon monoxide poisoning, Costa Rican authorities have said.