Use of astronomical telescopes to measure aerosol pollution.

ASTRONOMICAL observatories are particularly suited for studies of the background aerosol content of the atmosphere for four reasons. (1) The observatories are usually in remote locations away from the lights and smoke of cities. (2) Most observatories have standard equipment designed to correct the measured light fluxes of stars for the loss of brightness in the passage through the atmosphere (in other words, to correct for atmospheric extinction). (3) There is good global coverage of observatories. (4) Observations of the extinction of starlight by the atmosphere have been made for nearly forty years and are available for re-analysis. The last point is particularly important because there are no other reliable records of the condition of the atmosphere in remote locations.