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:
“It is true that the rivers went nosing like swine,
Tugging at banks, until they seemed
Bland belly-sounds in somnolent troughs,
That the air was heavy with the breath of these swine,
The breath of turgid summer, and
Heavy with thunder’s rattapallax....”
—Wallace Stevens (1879–1955)
“There were never in the world two opinions alike, any more than two hairs or two grains. Their most universal quality is diversity.”
—Michel de Montaigne (1533–1592)