About 78% of the volume of dry air is nitrogen gas (N2). Oxygen (O2), the component of air required by our bodies, comprises less than one fourth of dry air. Argon, a non-reactive gas, makes up slightly less than 1% of dry air. Carbon dioxide (CO2), a gas released from our bodies when we exhale, is present in even smaller quantities (less than one part per 1,000). Very minute amounts of many other naturally-occurring gases (such as neon, helium, methane and ammonia), as well as gases resulting from pollution, are present in air. Water vapor, when present, can occupy up to 5% of the total volume of air. When we breathe, nitrogen, oxygen and all the other components of air enter and exit our lungs.
Components of Dry Air
- Atmospheric air may contain 0.1% to 5% water vapor (H2O) by volume.
- Nitrogen gas (N2) 78%
- Oxygen gas (O2) 20%
- Argon 0.9%
- Carbon dioxide (CO2) 0.03%
- Minute amounts of: Neon Krypton Helium Xenon
- Other substances, including pollutants
Keywords: air | air quality | argon | breathing | carbon dioxide | gas | gases | lesson | nitrogen | oxygen | respiration | slides
- Moreno, N., Tharp, B., and Dresden, J. (2011) The Science of Air Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-74-3
- Photo courtesy of the National Cancer Institute.
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My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education