Public Health concerns over burials sites

I grew up in a country in Asia where burials are outside of buildings. There are many old crypts and tombs all over Italy, of historical importance, heritage and open to the public. For example, archaeological excavation revealed 6th century cemetery from a church basement in Lucca.

I could not find any information online regarding how these sites take precautions to protect public health. If you had any resources, please share with me. Thanks for tolerating my questions and curiosity.