The Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report says people who commit chemical suicide mix bath sulfur with toilet bowl cleaner and -- while in a confined space such as a vehicle -- and breathe in the resulting poisonous gas.
"During a three-month period in 2008 in Japan, 208 persons committed chemical suicide," the report says.
"Similar suicides have occurred in the United States and are believed to have resulted from the posting of directions for generating poisonous gas on the Internet."
The lethal gas generated by intentionally mixing household chemicals can leak from confined spaces -- triggering evacuations and exposing bystanders and first responders to injury, health officials warn.
"When responding to suspected chemical suicide incidents, emergency responders must take precautions to ensure both their safety and the safety of any bystanders in the immediate vicinity," federal health officials say.