Document 3eD5YRDLD8LBKKoQ5Vw4Qyjna

us PPG Industries, Inc. Chemicals P.O. Box 1000 Lake Charles, Louisiana 70602 TO: Distribution DATE: Jan. 3, 1990 FROM: Mai Hekmat Mtr SUBJECT: Noise monitoring The Lake Charles Noise Monitoring began in late August 1989 and continued to the end of the year. The purpose of the monitoring was to: evaluate jobs not previously monitored, insure that job classes not previously included in the Audiometric testing program remain so classified, and evaluate jobs currently included in the Audiometric testing program. To accomplish these goals, two samples were taken for every job description. This included both eight hour and twelve hour shifts. The equipment used for the monitoring was the MK-1 Audiodosemeter. It was calibrated before and after each sample was taken. Since all the data needed to be on an eight hour basis, the "twelve hour shift" samples were converted to equivalent eight hour readings. This was done using the formula: WVda where: Tt is the total time Tg is the total sample time Dg is dose calculated by the MK-1 DA is the dose used in the TWA formula. Da replaces D in the following formula to calculate TWA TWA* 16.61 Log(D/100)+90 where: TWA is the eight hour time weighted average D is actual accumulated dose in percent exposure. Distribution: Loren Anderson, G.O. 36W1 John Shepeard, LaPorte Ron Williams Clyde Dennis Bob McCorquadale SL 043225)