Inquiry (采购产品): exhaust ducts I have a client who is replacing the roof on a flat top roof system. Currently the exhaust ducts from laboratory hoods rise 8 feet from the flat roof. The roof needs to be replaced. the client is concerned about the roofer's employee exposure to chemicals during the roof removal and replacement. the lab hoods must remain on and operating during the roof replacement. Monitoring the chemical emissions is one way to identify the risk but it is retrospective and may ultimately boil down to engineering controls including the extension of the 13 x 10 inch ducts from the roof's surface. to a sufficient height to prevent entrapment of the vapor released from the ducts. have you had any experience with this kind of situation before and what recommendations do you have. **** Hidden Message ***** mark pheatt P.O. Box 41082 Sacramento,, CA 95841 USA Company: atlantic pacific environmental Title: industrial hygienist Phone: 916 768 6246 E-mail: apeconsulting@accessbee.com **** Hidden Message ***** apeconsulting@accessbee.com