Chapman is a regular writer on public health matters in leading Australian newspapers and blogs, having written some 470 opinion page and journalistic articles since 1981.
[3] His main research interests are in tobacco control, media discourses on health and illness, and risk communication.
He taught annual courses in Public Health Advocacy and Tobacco Control in the University of Sydney's MPH program.
He wrote a regular column, Smoke Signals, on public health matters for The Conversation[4] from January 2015-August 2017 which by February 2022 had been read 3.6 million times.
He was lead singer with a Sydney-based rock covers band, the Original Faux Pas,[12] from 2007 to 2012 and then with The Bleeding Hearts.
[15] In December 2017, Public Health England accused him of presenting factual errors during a Federal Government Enquiry[16] His full reply to these claims was published in Hansard (submission 313.1[17]