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  1. <text id=93AC0145>
  2. <title>
  3. National Air Pollutant Concentrations:1977-91
  4. </title>
  5. <history>
  6. Compact ALMANAC--United States Statistics         
  7. Environment & Weather                                
  8. </history>
  9. <article>
  10. <source>Time Almanac</source>
  11. <hdr>
  12. National Ambient Air Pollutant Concentrations(1): 1980-1991
  13. </hdr>
  14. <body>
  15. <p>[ug/m=micrograms of pollutant per cubic meter of air; ppm=parts per million.]
  16. </p>
  17. <table>
  18. <tblhdr><cell>Pollutant<cell>Unit<cell>Air quality standard(2)<cell>1980<cell>1985<cell>1990<cell>1991
  19. <row><cell type=a>Carbon monoxide<cell>ppm<cell type=i>9<cell type=i>8.90<cell type=i>7.00<cell type=i>5.85<cell type=i>5.57
  20. <row><cell>Ozone<cell>ppm<cell>.122<cell>.137<cell>.124<cell>.114<cell>.116
  21. <row><cell>Sulfur dioxide<cell>ppm<cell>.03<cell>.010<cell>.009<cell>.008<cell>.008
  22. <row><cell>Total suspended particulates<cell>ug/m<cell>75<cell>64.2<cell>48.6<cell>30.6<cell>30.3
  23. <row><cell>Nitrogen dioxide<cell>ppm<cell>.053<cell>.024<cell>.023<cell>.022<cell>.022
  24. <row><cell>Lead<cell>ug/m<cell>1.5<cell>.63<cell>.264<cell>.062<cell>.053
  25. <row><cell>INDEX(3)<cell><cell><cell><cell><cell><cell>
  26. <row><cell>Carbon monoxide<cell><cell>(4)9<cell>90<cell>72<cell>73<cell>72
  27. <row><cell>Ozone<cell><cell>122<cell>93<cell>87<cell>93<cell>101
  28. <row><cell>Sulfur dioxide<cell><cell>.03<cell>85<cell>69<cell>69<cell>70
  29. <row><cell>Total suspended particulates<cell><cell>75<cell>103<cell>78<cell>79<cell>80
  30. <row><cell>Nitrogen dioxide<cell><cell>.053<cell>92<cell>88<cell>92<cell>93
  31. <row><cell>Lead<cell><cell>1.5<cell>62<cell>25<cell>13<cell>10
  32. </table>
  33. <list style=hang>
  34. <item>1. Annual composite averages of pollutant based on daily 24-hour averages of monitoring stations, except carbon monoxide (based on second-highest, non-overlapping, 8-hour average); ozone, (average of second-highest daily maximum one hour value); and lead (quarterly average of ambient lead levels). Source: National Aerometric Data Bank.
  35. <item>2. Primary National Ambient Air Quality Standard (protects the public health).
  36. <item>3. Index unit:1979=100.
  37. <item>4. Values biased high due to type of measuring instruments used.
  38. </list>
  39. <p>Source: Except as noted, U.S. Environmental Protection Agency.
  40. </p>
  41. </body>
  42. </article>
  43. </text>
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