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 teenage son of former New York Yankees outfielder Brett Gardner, died of carbon monoxide poisoning, authorities in Costa Rica said Wednesday night. Miller Gardner, 14, died March 21 while the family was vacationing in Costa Rica and the cause of his sudden death was unknown before local officials conducted testing and found carboxyhemoglobin to be the cause.