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Concentration Analogies


One Part Per Million

  • one automobile in bumper-to-bumper traffic from Clevelandto San Francisco
  • one pancake in a stack four miles high
  • 1 inch in 16 miles
  • one minute in two years
  • one ounce in 32 tons
  • one cent in $10,000
  • .0001% (or 10,000 ppm equals 1%)

One Part Per Billion

  • one 4-inch hamburger in a chain of hamburgers circlingthe earth at the equator two-and-a-half times
  • one silver dollar in a roll of silver dollars stretching fromDetroit to Salt Lake City
  • one bogie in 3,500 golf tournaments
  • one kernel of corn in a 45-foot high, 16-foot diameter silo
  • one sheet in a roll of toilet paper stretching from New Yorkto London
  • one second of time in 32 years

One Part Per Trillion

  • one square foot of floor tile on a kitchen floor the size of Indiana
  • one drop of detergent in enough dishwater to fill a string of railroad tank cars ten miles long
  • one square inch in 250 square miles
  • one mile on a 2-month journey at the speed of light

One Part Per Quadrillion

  • one postage stamp on a letter the size of California and Oregon
  • one human hair out of all the hair on all the heads of all the people in the world
  • one mile on a journey of 170 light years

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