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Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, and Judith Dresden, MS.

About Air

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 

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932

Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education