1.   They have an extraordinary capability to taint food where they form compounds with fats which are detectable in parts per billion.

2.   As a biologist, I know that the cells in our body deal in parts per trillion or even quadrillion.

3.   But now, electronic devices can analyze the water sample and identify extremely small amounts of chemical pollutants in concentrations of as little as a few parts per billion.

4.   By concentrating the pollution, the system can remove contaminants down to a concentration as low as one part per billion.

5.   Carbon monoxide in outside street air measures between one and four parts per million, according to Mateel.

6.   Capsaicin, a substance that gives the sensation of heat when it hits nerve receptors, is analyzed in terms of parts per million using computerized devices.

7.   CO detectors measure the gas concentration being inhaled as parts per million, or PPM.

8.   Dwyer said human beings can smell something as diffuse as one part per billion.

9.   Humans can smell hydrogen sulfide in parts per billion.

10.   Less than one part per million formate is enough.