Fact 1: Amold spore has a negative impact on the respiratory system.

Fact 2: Mildew and mold spores are everywhere.

Given the two facts above, answer the question "what can affect the respiratory system?" with the following options: 
- Pollution
 - mildew
 - gas
 - influenza
 - oxygen
 - bacteria
 - smallpox
 - gold


 

  mildew       