What Is Ozone?
Most oxygen in the air consists of two joined oxygen atoms, O2. This is the oxygen we breathe. Add another oxygen atom, O3, and you have ozone. Here’s where it gets tricky because there are two kinds of ozone.
Both have the same chemical make up, but ozone high in the Earth’s atmosphere (the ozone layer) protects us from damaging ultraviolet sunlight. Ozone at ground level is a health hazard.
Why is it harmful?
Ground-level ozone is a pollutant that can cause a variety of health problems including chest pain, coughing, throat irritation, and congestion. Particularly susceptible are young children, the elderly, people with prior lung problems like emphysema, bronchitis, and asthma, and, to a lesser degree, otherwise healthy individuals who work or exercise outdoors. Ozone at ground level can also harm sensitive vegetation, including crops, and ecosystems.