Record Display for the EPA National Library Catalog


Main Title Field Testing and Evaluation of Methods for Measuring Visibility.
Author Cwalinski, Russel ; Lansinger, John M. ; Tank., William G. ;
CORP Author Northwest Environmental Technology Labs., Inc., Bellevue, Wash.;National Environmental Research Center, Research Triangle Park, N.C. Chemistry and Physics Lab.
Year Published 1975
Report Number EPA-68-02-1209; EPA/650/2-75/039;
Stock Number PB-251 548
Additional Subjects Air pollution ; Aerosols ; Visibility ; Measuring instruments ; Instrumentation ; Light transmission ; Transmissometers ; Haze ; Hazemeters(Meteorology) ; Photometers ; Transmissometers ; Nephelometers ; Humidity ; Air quality ; Comparison ; Performance evaluation ; Field tests ; Air pollution detection ; Telephotometers
Library Call Number Additional Info Location Last
NTIS  PB-251 548 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 98p
This report presents the results of a 3-month field study which was conducted to evaluate four methods for determining visibility. Three of the methods employed instruments to obtain visibility related measurements: a telephotometer measuring contrast between 'black' targets and the horizon sky; a transmissometer measuring light extinction over a folded horizontal path of approximately one mile; two integrating nephelometers measuring light scattering by aerosis in a local volume of air. One nephelometer was operated at a fixed location throughout the duration of the field tests and the other on occasions at random locations. The fourth method used a trained observer estimating visibility in four compass directions, and this method was used as a standard for comparison. Measurements were made under a variety of meteorological conditions and results are classified by the range of relative humidity under which they were obtained. The results of this project identify the telephotometer as the best choice of instrument for routine estimates of daylight visibility as an indicator of air quality.