In Air Quality
One measure of air pollution used in air quality standards is the atmospheric concentration of particulate matter. This measure is also sometimes referred to as the "particle number", although it is usually expressed in μg/m3 (micrograms per cubic metre).
Read more about this topic: Particle Number
Famous quotes containing the words air and/or quality:
“The air was clear. He seemed in ultimate peace
Except that he had no eyes. Rigid and bright
Upon the forehead, furred
With a light frost, crouched an outrageous bird.”
—Anthony Hecht (b. 1923)
“Anybody who knows the difference between the kind of conversation you have walking in the woods and the kind of conversation you have between the segments of a show on Nickelodeon can tell you that quality time exists. Quality time is when you and your child are together and keenly aware of each other. You are enjoying the same thing at the same time, even if it is just being in a room or going for a drive in the car. You are somehow in tune, even while daring to be silent together.”
—Louise Lague (20th century)