Reply: An "Old" Methodological Pitfall: Numbers of Deaths Due to Reducing Air Pollution Cannot Be Identified from Epidemiological Data.

From the Authors:

We thank Morfeld and Erren for their interest in our paper (1). In response to their comments, we agree that there are limitations to epidemiologic studies and that mortality data alone cannot be used to estimate burden, because everyone dies in the end; however, the cohort studies we cited used person-years of observations or the relative risk (of exposed and unexposed populations) in a specific time. There have been discussions about the points raised by Morfeld and Erren in their earlier letters to the editor, and responses by the authors (2–5) go into more statistical detail but have the same essential message.