On page 11 of his autobiography, Sacred and Stolen. Confessions of a Museum Director, Gary Vikan writes about how, in August 1988, the Walters Art Gallery took great pains to carefully construct shipping cases for the precious icons it was bringing from Greece for the exhibit, “Holy Image, Holy Space: Icons and Frescoes from Greece”. He also writes that “ the Greek conservators who accompanied those icons to America would smoke cigarettes as they worked over the icons and set their cups of coffee down on the painting surfaces—right on the faces of saints.” Scary stuff which no one would do today. However, in the "bad old days" American conservators could also exhibit dangerous behaviors. A colleague told me that she saw a filmed treatment (I believe it was from the 1960s) in which Sheldon Keck cleaned a painting while smoking a cigarette. We’ve come a long way in safe behavior.