Air Quality Standards

There are many standards relative to the purity of compressed air used for breathing purposes. However, the most generally accepted are those set forth by the Compressed Gas Association in its Pamphlet G-7.1-1989. These standards are incorporated by reference to OSHA 29 CFR 1910.134 as well as in NFPA 1500.

Contaminant CGA Grade D (1) CGA Grade E (1) NFPA 1500 (3) CSA Z180.1 (4)
Carbon Monoxide, PPM/v 10 10 10 5
Carbon Dioxide, PPM/v 1000 1000 1000 500
Condensed Hydrocarbons, mg/m 5 5 5 1
Total Hydrocarbons, as methane, PPM/v -- 25 -- --
Water Vapour, PPM/v, dew point (2) (2) 24 ppm -63F
Objectionable Odours None None None None
Nitrogen Dioxide (NO2), PPM/v -- -- -- 0.2
Nitrous Oxide (N2O), PPM/v -- -- -- 5
Sulfur Dioxide (SO2), PPM/v -- -- -- --
Halogenated Solvents, PPM/v -- -- -- --
Other Gaseous Contaminants -- -- -- (5)
Particulates, mg/m -- -- 5 1

--Indicates that the standard shows no limiting characteristics

  1. Compressed Gas Association Pamphlet G-7 1989, Compressed Air for Human Respiration and Compressed Gas Association Pamphlet G-7.1, Commodity Specification for Air. Pamphlet G-7 specifies Grade D as the minimum grade for routine use in self-contained or supplied-air protective breathing equipment, as used in industry, fire fighting, for general respiratory use. Pamphlet G-7 specifies Grade E as the minimum grade to be used for sports diving to 130 feet.
  2. For breathing air used in conjunction with self-contained breathing apparatus in extreme cold where moisture can condense and freeze, causing the breathing apparatus to malfunction, a dew point not to exceed -50F (63 pm v/v) or 10 degrees lower than the coldest temperature expected in the area is required.
  3. National Fire Protection Association Standard 1500, Fire Department Occupational Safety and Health Program, requires a water vapour level of 24 ppm v/v or less.
  4. Canadian Standards Association, Rexdale, Ontario, Standard CAN3-Z180.1-M85, Compressed Breathing Air and Systems.
  5. Maximum allowable content of tricholotrifluorethane, dichlorodifluoromethane and chlorodifluoromethane is 2 PPM/v for each. Unlisted contaminants shall not exceed one-tenth of the Threshold Limit Values (TLV's) for Chemical Substances in Workroom Air adopted by the American Conference of Governmental Industrial Hygienists (ACGIH).

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