Dear Colleagues, I would like to bring to your attention the following paper, Estimation of southern resident killer whale exposure to exhaust emissions from whale watching vessels and potential adverse health effects and toxicity thresholds. The article is currently in Press in Marine Pollution Bulletin (doi: 10.1016/j.marpolbul.2011.01.002), and can be found at www.sciencedirect.com. Abstract Southern resident killer whales in British Columbia and Washington are exposed to heavy vessel traffic. This study investigates their exposure to exhaust gases from whale-watching vessels by using a simple dispersion model incorporating data on whale and vessel behavior, atmospheric conditions, and output of airborne pollutants from the whale-watching fleet based on emissions data from regulatory agencies. Our findings suggest that current whale-watching guidelines are usually effective in limiting pollutant exposure to levels at or just below those at which measurable adverse health effects would be expected in killer whales. However, safe pollutant levels are exceeded under worst-case conditions and certain average- case conditions. To reduce killer whale exposure to exhaust we recommend: vessels position on the downwind side of whales, a maximum of 20 whale-watching vessels should be within 800 m at any given time, viewing periods should be limited, and current whale-watch guidelines and laws should be enforced. Please feel free to contact me with questions and for reprints. Cheers, Cara Cara Lachmuth, MSc 5195 William Head Rd. Victoria, BC V9C 4H5 Phone: (250) 884-6773 Email: lachmuth@zoology.ubc.ca