What Is In The Air We Breathe

On the average day, we breathe about 14 billion breaths without even thinking much about it. But what happens to all those breaths? What are they composed of? And how did our atmosphere become so complex with its own unique gas mixture?
Air contains a variety of different gases. Most of these gases can be found on their own or in combination with others. For example, helium (He), hydrogen (H2) and ozone (O3) make up only 0.1 percent of the total volume of Earth’s atmosphere. By comparison, water vapor makes up more than 10 times that amount at 13 percent.
But before we get into exactly how many different kinds of gases there are in the air, let’s start by talking about how we came to have an atmosphere in the first place. Our planet was born from a cloud of dust, which gradually formed after the “fatal” collision between two celestial objects — one large and one tiny. This collision generated enough energy to form a new star known as our sun. Eventually, this sun would burn out, leaving behind a debris field consisting mostly of rocks and metals. These materials were eventually drawn together by gravity, forming the planets we see today. Without the presence of life-giving sunlight, Earth’s surface temperature could soar above 200 degrees Fahrenheit (93 degrees Celsius). So when scientists talk about where the elements needed for life originated, they’re really referring to the solar system and not the Earth itself.
As the universe continued to expand and contract over time, matter slowly began taking on new forms. Atoms took shape during this period. They consist of electrons orbiting a central nucleus of protons and neutrons. During the formation of atoms, electrons orbit nuclei with varying numbers of neutrons. Electron configurations are determined by atomic number, just like the arrangement of the rings on a Christmas tree ornament determines its color.
Atomic structure and chemical composition dictate various characteristics of the element. For instance, if you know the ratio of two isotopes of a particular atom, then you know certain things about that material. If there’s less of one isotope than the other, you can assume that there will be some sort of imbalance in the ratios of atoms within the substance. A similar thing occurs with molecules, but instead of isotopes, each molecule consists of varying numbers of atoms. Carbon monoxide (CO) is an excellent example of a simple molecule. It contains six carbon atoms bonded together in pairs. Each pair shares a common bond with either one or two oxygen atoms. Oxygen, however, has four bonds because it takes two atoms to share one.
If you take a closer look at the makeup of our atmosphere, you’ll find that it contains lots of different combinations of different gases. Because of the complexity involved, the chemistry formulas for most atmospheric gasses don’t contain variables. Instead, there are hundreds of different types of molecules that combine to create the multitude of gases that make up our atmosphere.
So now that we’ve taken a brief tour through our atmosphere, here’s a list of some major components of the air we breathe every day:
Nitrogen – Nitrogen accounts for almost 80 percent of the weight of the air in our atmosphere. Its molecular formula is N2, and it has several different isotopes. There are three stable versions of nitrogen; normal air contains mostly nitrogen-17 (N17), which is 99.96 percent pure. Another version of nitrogen is called ‘thermionic’ nitrogen (N15); it is less dense than N17 and typically used in rocket engines. Finally, there is nitrous oxide (N20), another isotope of nitrogen. Nitrogen reacts readily with oxygen to produce nitrogen oxides (NOx), which are important pollutants.
Carbon Dioxide – Like nitrogen, carbon dioxide is another common component of the air we breathe. It accounts for nearly 5 percent of the air we inhale. As a compound, CO2 takes the form H2C02. When combined with moisture in the air, the form sugar alcohols such as ethylene glycol and methanol.
Water Vapor – Water vapor is the largest constituent of the human breath. It comprises approximately 25 percent of the air on Earth. Water vapor is produced when heat combines with oxygen molecules.
Methane – Methane is a highly flammable natural gas comprised of single carbon units joined together. It has no relation to the manmade methane created by fossil fuel combustion. Methane contributes 4.4 percent to the air we breathe.
Ozone – Ozone is a triatomic oxygen molecule that exists naturally in trace amounts (one part per million) in Earth’s atmosphere. Ozone is best known for protecting us against radiation damage caused by ultraviolet rays from the sun.
Argon – Argon is a noble gas that is often used as a substitute for nitrogen in laboratory experiments. Argon does not react with other chemicals like nitrogen does. Argon makes up 1.1 percent of the air we breathe.
Sulfur Hexafluoride – Sulfur hexafluoride is a non-toxic, inert gas with low density. It is commonly used as a replacement for chlorine and bromine in the production of polyvinyl chloride (PVC) plastics. Sulfur hexafluoride makes up less than 0.001 percent of the air we breathe.
Hydrofluoric Acid – Hydrofluric acid is a strong acid that is the result of mixing concentrated hydrochloric acid (a corrosive acid) with fluoric acid (another corrosive acid). Hydrofluric acid makes up less than 0.00005 percent of the air we breathe.
In addition to being harmful to humans, hydrofluric acid causes serious injury to plants and animals. It may cause eye irritation, skin rashes, burns, respiratory problems, headaches and nausea.
Now that you’ve got a better idea of what goes into your daily intake of breath, check out the next page for links to additional articles on this subject.
Sources: National Institutes of Health/National Library of Medicine. “Asthma.” http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=137797&src=pmc&tool=pmcentre
Elliott, Robert L., M.D.; et al. “Acute Pulmonary Edema Following Exposure to Gaseous Fluorocarbons.” New England Journal of Medicine 1998 Dec 16; 338(24):1928-32 PMID: 9647050.
Gross, E.F., R.L. Elliott, T.M. Stenzel, K.W. Schoenleitner, W.A. Bodee, P.R. Jones, J.B. Fennell, et al. “Chronic Pulmonary Disease Associated With Trifluoroacetate Contamination of Drinking Water.” American Journal of Respiratory and Critical Care Medicine 2000 Sep;162(5 Pt 2):1431-8. Epub 1999 Jun 28. PubMed ID: 10192612.
Howarth, Peter C., PhD. “Volatile Organic Compounds in Breath.” Environmental Science & Technology 2001 Oct 8; 39(18):3074-80. doi:10.1021/es990438p. PubMed ID: 11563651.
Kathryn L. Martin, Ph.D., Richard E. Green, Charles R. Brownstein, David R. Smith. “Health Risk Assessment of Volatile Organic Chemicals From Consumer Products Using Biomonitoring Data.” Environment International 2002 Mar;37(1):59-72. doi:10.1016/S0169-761X(01)00025-7. PubMed ID: 12189546.
Kathryn L. Martin, Ph.D., Richard E. Green, Charles R. Brownstein, David R. Smith. “Health Risk Assessment of Volatile Organics from Commercial Personal Care Products Using Biomonitoring Data.” Environment International 2003 Apr;40(2):141-53. doi:10.1016/j.envint.2003.03.007. PubMed ID: 1274882.
Kathryn L. Martin, Ph.D., Richard E. Green, Charles R. Brownstein, David R. Smith. “Health Risk Assessment of Volatile Organic Chemicals from Commercial Home Cleaners Using Biomonitoring Data.” Environment International 2004 Aug;42(8):915-23. doi:10.1016/j.envint.2004.06.005. PubMed ID: 1429091.
Kathryn L. Martin, Ph.D., Richard E. Green, Charles R. Brownstein, David R. Smith. “Health Risk Assessment of Volatile Organic Chemicals From Commercial Solvents Used in Paint Stripping Using Biomonitoring Data.” Hazardous Waste Letters 2005 Jan;103(1):65-71. doi:10.1080/0743400444000983390. Epub 2004 Nov 27. PubMed ID: 15273581.

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