CSIRO Marine and Atmospheric Research
 
 

Typical concentrations of greenhouse gases and air pollutants
Information sheet

How does the composition of pristine air and urban air compare? This table shows typical concentrations of some key gases in remote and city environments.

Gas Clean air Urban air Ambient air quality: National Environment Protection Measure
Carbon dioxide (ppm) 360 350-600  
Methane (ppb) 1700 1700-2500  
Nitrous oxide (ppb) 315 315-350  
CFC-11 (ppt) 260 300-500  
Ozone (ppb) 15-35 0-100 1 hour: 100
4 hours: 80
Nitrogen oxides (ppb) 0.005-0.02 1-800 Nitrogen dioxide
1 hour: 125
1 year: 30
Carbon monoxide (ppm) 0.03-0.10 0.05-50 8 hours: 9
Aerosol (PM10*)
Aerosol (PM10*)
(micrograms per cubic metre)		 Less than 10 25 50

*PM10 aerosol are atmospheric particles with diameter less than 10 microns. (A micron is a millionth of a metre, or a thousandth of a millimetre. A human hair is about 60 microns wide.)

  • ppm is parts per million by volume (360 ppm, for example, represents a concentration of
    0.36 per cent by volume)
  • ppb is parts per billion by volume
  • ppt is parts per trillion by volume

Paul Holper
February 2000

Site updated 1st October 2003

Modified: April 3, 2008

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