Is Smallpox Virus Still Present In The Environment?

In reading about the Native Americans, I became interested in smallpox. I understand that smallpox has been eradicated by vaccination. I can see how vaccination would keep people from becoming infected by smallpox. But wouldn’t the virus still be present in the environment and capable of infecting the non-inoculated?
Or, does the virus require something like a “critical mass” of infected hosts to survive.