In the excerpt, "sterile" refers to an environment that is free from bacteria or other living microorganisms, suggesting a clean, sanitized space like that found in a hospital. The word implies not just cleanliness but also an absence of life or organic smells typically associated with a more natural environment.
The word that provides the clearest contextual clue for "sterile" in this excerpt is "Antiseptic." This word evokes a strong association with cleanliness and the medical setting, indicating a lack of unwanted odors and reinforcing the idea of the environment being devoid of organic scents.