He began photographing in the 1980s during the final years of apartheid and produced a number of bodies of work documenting the resultant societal conditions and political climate in South Africa.
Since then he has produced a number of photographic advocacy projects, working with charities and campaigning organizations including The Global Fund, Médecins Sans Frontières, Treatment Action Campaign, the International HIV/AIDS Alliance, ActionAid, the Terrence Higgins Trust, Shelter, Leonard Cheshire Disability, UNICEF and Concern Worldwide.
Mendel started the project after travelling to the UK, and then India to document the damage caused by floods a few weeks apart from each other.
[6] He describes the project as "my attempt to explore the effects of climate change in an intimate way, taking us beyond faceless statistics and into the individual experiences of its victims."
While awareness about the disease was growing rapidly at the time, antiretroviral treatment (ART) was still very difficult to access for many of the continent's poorest.
[10][11][12][13] The ongoing chapter of his work on AIDS, Through Positive Eyes, is a collaborative project with the UCLA Art and Global Health Center.
[15] Developed by Davide Gere at the UCLA, the workshops that form part of the project are led by fellow photographer Crispin Hughes.
Mendel belonged to part of a generation of "struggle photographers", committed to documenting the conflict and political upheavals of the 1980s in South Africa.