15.48.060 Filtration required when.
   A.   Those outdoor light fixtures requiring a filter in Section 15.48.070 shall be equipped with a filter whose transmission is less than five percent total emergent flux at wavelengths less than three thousand nine hundred angstroms. Total emergent flux is defined as that between three thousand and seven thousand angstrom units.
   B.   It is recommended that existing mercury vapor fixtures shall be equipped with a filter whose transmission is less than ten percent total emergent flux at wavelengths less than four thousand four hundred angstroms. Total emergent flux is defined as that between three thousand and seven thousand angstrom units.
   C.   Low pressure sodium lamps are the preferred lamp for minimizing adverse effects on astronomical observations.
(Ord. 911 § 3.02, 1983)