Fact 1: Air pollution harms the respiratory and circulatory systems.

Fact 2: Exposure to ozone can diminish lung function and increase susceptibility to respiratory infection.

Given the two facts above, answer the question "Which type of pollution is most harmful to lungs?" with the following options: 
- Lead
 - air
 - Cars
 - oil
 - acid
 - CFCs
 - SO2
 - mold


 

  air       