You sometimes hear the terms parts per million (ppm) or parts per billion (ppb) to describe the concentration of something in water, soil, air, or bodily fluids. Often, ppm or ppb refers to the levels of a pollutant of some kind. In the pest control business, we sometimes use ppm or ppb to refer to trace amounts (residues) of pesticides that may remain in or on food, water, air, or surfaces after a pesticide has been applied.

Comparatively speaking, a part per million is a very small amount. A part per billion is so small that it is even hard to imagine. Here are some examples to help you understand just how tiny these residues really are:

Parts Per Million (ppm)

• 1 ppm is 1 inch in 16 miles
• 1 ppm is one penny in $10,000
• 1 ppm is the length of an average car compared to the distance from New York to Los Angeles
• 1 ppm is a 1 gram needle in a ton of hay
• 1 ppm is the thickness of a postage stamp compared to the height of the Washington Monument
• 1 ppm is one drop of water diluted in the fuel tank of a compact car
• 1 ppm is 32 seconds out of a year

Parts Per Billion (ppb)

• 1 ppb is 1 inch in 16,000 miles
• 1 ppb is one penny in $10,000,000.
• 1 ppb is one drop of water in 80,000 fifths of whiskey
• 1 ppb is one drop of water in 250 chemical drums
• 1 ppb is 3 seconds out of a century