and death. Carbon monoxide is extremely dangerous to bystanders and people who may discover the body; right-to-die advocate Philip Nitschke has therefore recommended against this method. Before air quality regulations and catalytic converters, suicide by carbon monoxide poisoning was often achieved by running a car's engine in an enclosed space such as a garage, or by redirecting a running car's exhaust back inside the cabin with a hose. Motor car exhaust may have contained up to 25% carbon monoxide. Catalytic converters found on all modern automobiles eliminate over 99% of carbon monoxide produced. As a further complication, the amount of unburned gasoline in emissions can make exhaust unbearable to breathe well before a person loses consciousness. Charcoal-burning suicide induces death from carbon monoxide poisoning. Originally used in Hong Kong, it spread to Japan, where small charcoal-burning heaters (hibachi) or stoves (shichirin) have been used in a sealed room. By 2001, this method accounted for 25% of deaths from suicide in Japan. Nonfatal attempts can result in severe brain damage due to cerebral anoxia. Other toxins Gas-oven suicide was a common method of suicide in the early to mid-20th centuries in some North American and European countries. Household gas was originally coal gas, also called illuminating gas, or town gas, which was composed of methane, hydrogen and carbon monoxide. Stoves of this era required one to manually ignite a pilot light with a match; without the combustion the gas cloud would spread unimpeded. Carbon monoxide poisoning was the proximate cause of death. Natural gas, introduced in the 1960s, is composed of methane, ethane and an odorant added for safety. The suicide rates by domestic gas fell from 1960 to 1980, as changes were made to the formula to make it less lethal. Shooting In the United States suicide by firearm is the most lethal method of suicide, resulting in a fatality 90% of the time, and is thus the leading cause of death by suicide as of 2017. Worldwide, firearm prevalence in suicides varies widely, depending on the acceptance and availability of firearms in a culture. The use of firearms in suicides ranges from less than 10% in Australia to 50.5% in the U.S., where it is the most common method of suicide. Generally, the bullet will be aimed at point-blank range. Surviving a self-inflicted gunshot may result in severe chronic pain as well as reduced cognitive abilities and motor function,