what can affect the respiratory system?
Pollution mildew gas influenza oxygen bacteria smallpox gold
A B C D E F G H
Mildew and mold spores are everywhere.
mildew can affect the respiratory system
what can affect the respiratory system? (A) Pollution (B) mildew (C) gas (D) influenza (E) oxygen (F) bacteria (G) smallpox (H) gold