Household, Industrial, and Occupational Exposures
Inhaled toxins
Carbon monoxide binds hemoglobin with roughly 200-fold greater affinity than oxygen, shifting the dissociation curve left and impairing mitochondrial cytochrome oxidase. Symptoms are nonspecific; pulse oximetry and calculated saturation are normal, so co-oximetry is required. Half-life is about 4–6 hours in room air, 90 minutes on high-flow oxygen, and shorter with hyperbaric therapy. Hyperbaric oxygen is considered for syncope, neurologic deficits, ischemia, severe acidosis, or COHb above roughly 25 percent (lower in pregnancy).
Cyanide from smoke inhalation or industrial salts causes lactic acidosis, seizures, and cardiovascular collapse; hydroxocobalamin is preferred. Hydrogen sulfide and simple asphyxiants cause rapid collapse in confined spaces - rescuers must not enter unprotected.
Irritant gases differ in water solubility: highly soluble ammonia and chlorine injure the upper airway with immediate symptoms, while poorly soluble phosgene and nitrogen oxides cause delayed pulmonary edema after a symptom-free interval.
Caustics and hydrocarbons
Alkalis cause deep liquefactive necrosis; acids cause coagulative burns. Do not induce vomiting, do not place a nasogastric tube blindly, and do not give charcoal; perform endoscopy within 12–24 hours to grade injury. Hydrocarbons are a low systemic but high aspiration risk - never induce emesis, and charcoal offers little benefit.
Occupational principles
Know the difference between OSHA permissible exposure limits, biological exposure indices, and sentinel health events. Take-home lead contamination of family members is a classic question.
Rule of thumb: dry decontamination (remove clothing, brush off powder) precedes washing, and staff protection always precedes patient decontamination.