Excessive breathing of poisonous fumes. Toxic gas inhalation can result from breathing a number of different fumes, including cyanide or carbon monoxide, which is produced by gasoline-burning engines, defective cooking equipment, charcoal grills, and fires. If inhaled in large amounts, carbon monoxide will replace the oxygen in the bloodstream and reduce the supply of oxygen to the cells in the body. Symptoms of toxic gas inhalation include pale or bluish skin, headache, nausea, vomiting, and confusion. People who have inhaled poison gas need fresh air as soon as they can safely be moved. Emergency medical assistance must be sought.