Simon has recently retired after a career in respiratory protection research for over thirty-eight years. This started with doctoral work on sorbent media, followed by employment with respirator manufacturers: first Racal Health and Safety as research manager, and after its takeover by 3M, continuation as a research scientist in Brockville, Ontario. He worked in filter development and evaluation methods for new products for military, industrial, healthcare and emergency responder applications. Simon has been contributing to standards development for over fifteen years and currently chairs the ISO working group creating standards for respirators for emergency responders and contributes to several Canadian Standard Association committees addressing respiratory protection and to the US National Academies of Sciences, Engineering and Medicine PPE committee. Simon has formerly served as President of the International Society for Respiratory Protection and as Chair of the American Industrial Hygiene Association Respiratory Protection Committee.