A number of air sampling stations which are established in a given geographical region
at which measurements of both pollutant concentrations and meteorological quantities
(wind speed, direction, rain fall, humidity, etc.) are made to determine the extent
and the nature of the air pollution
and to establish trends in the concentrations of the air pollutants with time.
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2173
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook