During 1989, many of the country's national parks were disappearing behind the curtain of air pollution. The biological diversity that is sheltered by the parks is at risk since scientists had noted that ozone damage and acid rain has caused the plans to be ill. A few examples of the negative effects on the plant life is the death of the Jeffery Pine Trees in Sequoia, plants that experienced ozone damage showed problems in roots and shoot growth. Another example is from the parks such as Santa Monica Recreation Area and Indiana Dunes National Monument, where in high levels of ozone damage have eradicated many species of lichen.
