Water Fluoridation Maps
View water fluoridation maps for Australia and New Zealand.
What does ppm mean?
This is an abbreviation for "parts per million" and it also can be expressed as milligrams per liter (mg/L). This measurement is the mass of a chemical or contaminate per unit volume of water. Seeing ppm or mg/L on a lab report means the same thing.
One ppm is equivalent to the absolute fractional amount multiplied by one million. A better way to think of ppm is to visualize putting four drops of ink in a 55-gallon barrel of water and mixing it thoroughly. This procedure would produce an ink concentration of 1 ppm. Some other analogies that may help you visualize the scale involved with ppm. One ppm is like:
- one inch in 16 miles,
- one second in 11.5 days,
- one minute in two years.
An even smaller concentration measurement is parts per billion (ppb). One ppb is one part in 1 billion. Because a ppb is a much lower concentration, some analogies would be :
- one sheet in a roll of toilet paper stretching from New York to London,
- one second in nearly 32 years, or
- one pinch of salt in 10 tons of potato chips.