Hi, Homelessness is a public health issue and it can have many negative impacts on a local community.

Hi,
Homelessness is a public health issue and it can have many negative impacts on a local community. What aspects of homelessness have the most influence beyond the local community and have impacts for the global community? Think in terms of things like lifestyle, population dynamics, disease, climate change, disaster response, etc.
And With a focus on the entire planet, why does homelessness topic matter?