There was an excellent issue of Jan Oosthoek's Exploring Environmental History podcast. In this podcast Oosthoek, who is a historian himself, mainly interviews other historians on topics of environmental history. This is a very good format for podcast as is also shown by New Books in History (another historian interviewing historians) and Shrink Rap Radio (A psychologist interviewing psychologists). Ample time for a conversation between two professionals, one knowing what he is talking about and the other knowing exactly to ask the right questions.
The absolute best podcast chapters of this kind are where the interviewed party is really excited and brings even more life than usual in the conversation. This was the case with Dolly Jørgensen, when she appeared on the EEH podcast. Oosthoek has her first talk about a cooperation initiative for historians in a network of medievalists, but it gets really good when she begins to talk about her own work.
Jørgensen did research into waste management in medieval cities. You'd expect those cities to be unbelievably dirty, but it turns out they were not. She claims that all modern methods of collecting garbage and financing this with taxes stem from this era. Indeed, I thought that to be a 19th century invention. Medieval cities were kept clean and maintained. Perhaps the truly big, polluted, crowded and unhealthy cities come with the heavy urbanization that started right after the Middle Ages and reached a low point as far as crowdedness and pollution is concerned in the first waves of industrialization.
More Exploring Environmental History:
New weeds in Africa,
Biological invasions and transformations,
Environmental history: an applied science,
Defining Environmental History with Marc Hall,
Defining Environmental History - Paul Warde.