Nassau County EMT Practice Test

The key idea is that inhaled air can be made safer by increasing the proportion of breathable gas, which dilutes other airborne substances. In EMS practice, giving supplemental oxygen raises the fraction of inspired oxygen (FiO2), so the amount of toxic or low-oxygen gas that reaches the lungs is effectively reduced. Oxygen directly supports metabolism and improves oxygen delivery to tissues, which is why it’s the chosen diluent in this context.

Nitrogen is the main component of air and is largely inert, not something we actively use to dilute inhaled toxins. Carbon dioxide would worsen the patient’s respiratory status and acid-base balance. Helium-oxygen mixtures exist for specific airway conditions but aren’t used broadly to dilute airborne toxins. So, supplemental oxygen is the appropriate choice to dilute airborne substances and support breathing.