Multiple choice

Which type of pollution is known as the “silent killer”?

  1. Nitrogen oxides

  2. Carbon monoxide

  3. Carbon dioxide

  4. Particulate matter

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbon monoxide is often called the silent killer because it is undetectable by human senses and can cause death by suffocation before a person realizes they are being exposed.