Ozone becomes a moderate health risk when it reaches a level of 55 parts per billion (ppb) in the air. Write an inequality that describes a safe ozone level. What inequality symbol will you use and why?
The inequality that describes a safe ozone level is:
Ozone level < 55 ppb
I will use the less than symbol (<) because it indicates that the ozone level must be below 55 ppb in order to be considered safe.