because it reacts with sensitive lung tissue, causing harmful changes in breathing passages.
Children, the elderly and individuals with respiratory diseases are especially harmed by ozone. Even healthy individuals can be harmed if they attempt strenuous activity on days with high ozone...those days should be used for inside low physical stress activity.
REMEMBER, this may seem like a small contribution by you as an individual, but if we can get solid public involvement, working together we CAN make a real difference!