Question: Mary Ochsenhirt Amdur studied the effects of smog on what town? 
Sentence (from "Where Once We Walked"): Where Once We Walked (full title: "Where Once We Walked: A Guide to the Jewish Communities Destroyed in The Holocaust"), compiled by noted genealogist Gary Mokotoff and Sallyann Amdur Sack, is a gazetteer of 37,000 town names in Central and Eastern Europe focusing on those with Jewish populations in the 19th and first half of the 20th centuries and most of whose Jewish communities were almost or completely destroyed during The Holocaust.
Relevant evidence: No