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:
“Approximately 80% of our air pollution stems from hydrocarbons released by vegetation, so let’s not go overboard in setting and enforcing tough emission standards from man-made sources.”
—Ronald Reagan (b. 1911)
“Spindly branches of buttercups were secreted among gleaming stems still moist at the roots from last night’s rain that had washed and refreshed the entire wood, had dowered it in poignant transparency, the unique, inconsolable quality of rainy countries, as if all was glimpsed through tears.”
—Angela Carter (1940–1992)