Dalton's LawAs we think about the rules we inadvertently follow every day without even realizing it, like speed limits and wearing seat belts, Respiratory therapists need to remember that there are gas laws that we follow every day without realizing it. that too. This article will focus on a gas law called Dalton's law of partial pressures. For respiratory therapists to fully understand the importance of Dalton's Law, we need to explain what this law says, how it applies to respiratory care, and what technological advances have been made to change the use of this law. In the early 1800s, a scientist named John Dalton developed a theory that we now call Dalton's law of partial pressure. John Dalton developed this law by experimenting with gases in the atmosphere. “Dalton's experiments with gases led him to discover that the total pressure of a mixture of gases was equivalent to the sum of the partial pressures exerted by each individual gas while occupying the same space” (A+E Networks, 2013 ). Mathematically, Dalton explained this law by stating: Ptotal= P1+P2+P3……Pn. These preliminary experiments performed by Dalton were based on the original 760 torr or 760 mmHg discovered earlier by Torricelli. Dalton then realized that the 760 mmHg in the atmosphere was made up of gases such as oxygen, nitrogen, carbon dioxide and a few other trace gases. The pressure released by each of these gases is considered to be the partial pressure of the total atmospheric pressure. The percentages of these gases in the atmosphere at sea level are nitrogen 78.08%, oxygen 20.95%, carbon dioxide 0.03% and the remaining trace gases 0.94%, which which represents a total of 100% in the atmosphere. Thinking about Dalton's law partial pressures...... middle of paper ...... partial pressures. Over many years of development, we now widely use oxygen therapy to treat people suffering from altitude sickness, and can use hyperbaric oxygen therapy to treat divers affected by decompression sickness. As respiratory therapists, we owe the success of these two treatments to a scientist named John Dalton for the development of Dalton.AE Networks' Law of Partial Pressures. (2013). Biography of John Dalton. Retrieved from http://www.biography.com/people/john-dalton-9265201?page=1 Harvard Health Publications. (2013). Decompression sickness. Retrieved from http://www.drugs.com/health-guide/decompression-sickness.html Pendleton, LD (November 7, 1999). When Humans Fly High: What Pilots Need to Know About High Altitude Physiology, Hypoxia, and Rapid Decompression. Retrieved from http://www.avweb.com/news/aeromed/181893-1.html?redirected=1