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On too many occasions, national park visitors are greeted with health warnings, forcing them to change plans or limit their time outside. High pollution levels often occur during the warmer months, the times when many parks experience their greatest visitation.
This year, the Code Red ranking for the smoggiest parks is based on the federal health standard for ozone, and Sequoia-Kings Canyon tops this list. The park has recorded hundreds of unhealthful air days over the past five years, rivaling our most polluted urban areas, including Los Angeles.
Much like sunburn affects the skin, ozone inflames the lining of the lungs, causing permanent damage with repeated exposure. Symptoms include shortness of breath, coughing, wheezing, and throat irritation. EPA estimates that nearly one-third of U.S. citizens are at a higher risk for experiencing health problems from ozone, including children, people suffering from respiratory
diseases such as asthma, and otherwise healthy adults who are active outdoors.15
Many trees and other plants suffer damage from ozone at even lower levels than those established to protect humans. Ozone can damage and kill leaves, affecting a plant's ability to produce food. In turn, this can reduce plant growth and resistance to diseases and pests, potentially leading to long-term effects on forests and ecosystems.16 A broad range of plants, from sequoia seedlings and ponderosa pines to tulip trees and blackberries are sensitive to ozone pollution.17
UNHEALTHFUL AIR DAYS IN CITIES AND NATIONAL PARKS
1999-2003
| Cumulative totals of unhealthful air days from all monitors are not readily available for the cities shown. Instead, the chart compares the total number of unhealthful days recorded over a five-year period at one representative monitor from each city and national park. This illustrates how park air quality compares with that in cities. |
Acid Rain, Sleet, and Snow
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Code Red compares the amount of acid precipitation that falls on parks to rank the most acidic. Smokestacks and tailpipes emit pollution into the atmosphere that eventually falls back into water and onto soils. Pollution is dissolved in rain that can be as acidic as vinegar. It can also fall to earth as snow, fog, low hanging clouds, or as dry particles.
Some park ecosystems receive more pollution than they can naturally process. Streams can be too acidic to support fish, amphibians, and aquatic insects while forest soils may be overloaded with this pollution, affecting the health of both the forests and the soil organisms. The pollution can even harm coastal waters, producing algal blooms that choke out other forms of life.
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