Frequently Asked Questions
What is acid Rain?
Acid Rain is caused when sulfur dioxide (SO2) and nitrogen oxides (NOx) -- pollutants released from burning coal, oil, and other fossil fuels -- chemically react with other substances in the atmosphere to form acidic compounds. When these acidic compounds are carried down from the atmosphere in rain, fog, snow or dust, they can end up in lakes and streams, on buildings and monuments or on trees and land. They can harm fish, damage high-altitude forests and can deteriorate buildings and historical monuments. The pollutants that cause acid rain also have been known to worsen asthma and other lung ailments and to impair visibility in many regions of the nation including scenic vistas of our national parks.
How does acid rain affect public health?
High levels of sulfur in the air have been proven to cause and aggravate various types of lung disorders. These lung disorders, which affect some people's ability to breathe, have led to both increased disease rates and mortality in sensitive populations, such as young children and elderly. Low levels of acidic compounds and acid mist commonly found in the air in the eastern United States also can pose health problems. EPA has been asked by a panel of outside experts to investigate this issue.
How does acid rain affect lakes and streams?
When acid rain passes through soils or falls directly into lakes and streams, it can increase the acidity of the water. Higher acidity can hinder some fish and water plants from reproducing, growing and surviving. In some acidified lakes and streams, entire fish populations have disappeared. For example, many lakes in the Adirondack Mountains of New York and many streams in the Appalachian mountain region have lost trout and other aquatic life due to acid rain. The effects of acid rain can be either"chronic" or "episodic". Chronic acidity occurs when lakes and streams cannot counteract the chemical changes brought about by acid rain. This results in constant high acidity levels in the water. Episodic acidity occurs only periodically, primarily as a result of storms or snowmelts that empty large amounts of acidic water into lakes and streams. In the case of episodic acidity, lakes and streams suffer from intense but short-lived increases in acidity. In the spring, when such episodes often occur, newly hatched fish can be killed. Some lakes and streams are naturally more sensitive to acid rain because they rest in soil that cannot neutralize acids. In the mid-1980's, the U.S. Environmental Agency (EPA) and other federal agencies commissioned a National Surface Water Survey to examine the effect of acid rain in over 1,000 lakes and thousand of miles of streams. From this survey, EPA determined that acid rain was the primary cause of acidic bodies of water.
Where are the acidified lakes and streams located?
According to the National Surface Water Survey, about 14 percent of the lakes larger than 10 acres in the Adirondack Mountains in New York are chronically acidic. About 12 percent of streams are acidic in the mid-Atlantic Highlands (which include southeaster New York, most of Pennsylvania, and portions of Maryland, West Virginia, and Virginia) and the mid-Appalachians (which include Virginia, West Virginia, Maryland, Pennsylvania, and North Carolina). Other affected areas include Florida and the Upper Peninsula of Michigan. In addition, many lakes and streams through the United States are sensitive to episodic acidification. The Canadian government has estimated that 14,000 lakes in eastern Canada are acidic, in part because of sulfur dioxide emissions from U.S. utilities and industrial plants.
How does acid rain harm forests?
Acid Rain can contribute to forest damage by impairing the ability of some types of trees to grow and flight disease. Acid rain also can strip forest soils of essential nutrients, which hurts the productivity of forests.
What forest regions are most affected by acid rain?
Acid rain has primarily impacted high-elevation spruce trees that grow on the ridges of the Appalachian Mountains from Maine to Georgia, including spruce trees in the Shenandoah National Park and the Great Smoky Mountains National Park.
How does acid rain affect visibility?
The chemical reactions that sulfur dioxide and nitrogen oxides undergo in the atmosphere lead to the formation of particles that can reduce the distance we see and the clarity of our scenic vistas These particles account for over 50 percent of the visibility problems in the the eastern United States. In the West, such particles also have been blamed for visibility problems in the Grand Canyon and other national parks.
Does acid rain contribute to the decay of buildings and monuments?
Acid rain contributes to the corrosion of metals and to the deterioration and soiling of stone and paint on buildings, statues and other structures of cultural significance. The damage inflicted on cultural objects is especially costly since a loss of detail seriously depreciates the objects' value to society.
How are we solving the problem nationally?
Federal legislation will require substantial reductions in sulfur dioxide and nitrogen oxides emissions, which will help improve environmental and health conditions in the United States. Scientists project that emissions reductions will increase the visual range in the eastern United States by 30 percent and reduce the deterioration of buildings and monuments. In addition, scientists predict that the Acid Rain Program will virtually eliminate acidity in the lakes and streams of the Adirondacks and help bodies of water and forests throughout the United States recover from the effects of acid rain. The latest EPA information on the 256 largest power plants in the U.S. shows a 20 percent reduction the SO2 emissions between 1990 and 1994, the first year the acid rain rules were in effect. Even larger reductions are expected as smaller power plants begin to make SO2 reductions required by the acid rain rules. Utilities have successfully reduced SO2 emissions, but will need to do more work at some boilers to meet NOx emission reduction targets that have not yet been set by EPA.
How do utilities control acid gas emission?
Most utilities have converted from high sulfur Midwestern coal (2.5 to 4.5 percent sulfur) to low sulfur coals largely produced in the West. Burning this low-sulfur coal (usually less than 1.5 percent sulfur) can reduce acid gas emissions by as much as 90 percent. Some utilities that used scrubbers to reduce SO2 emissions have disconnected them because SO2 emissions from Western coal are so low.
How does EPA keep track of acid gas emissions?
Utilities are required to install very accurate continuous emissions monitoring systems to record acid gas emissions every hour the plant is operating. These systems produce an annual report of SO2 and NOx emissions. Each report is sent electronically to EPA, where allowances and emissions are compared. Utilities that emit SO2 and NOx in excess of their allowances must pay $2,000 for each ton of excess emissions. When a company emits less than its limit, it may trade or sell the difference to another company to use.
What is ozone air pollution?
Ozone is a highly reactive reactive gas that is a form of oxygen (O3). It is the main component of the air pollution known as smog. Ozone reacts chemically ("oxidizes") with internal body tissues that it comes in contact with, such as those in the lung. It also reacts with other materials such as rubber compounds, breaking them down.
What's the difference between good ozone and bad ozone?
"Good" ozone in the upper atmosphere occurs naturally. It is a protective layer that screens out harmful ultraviolet rays. "Bad" ozone at ground-level results from pollution that reacts in the presence of sunlight. It can harm people with respiratory disease, children and healthy adults that exercise outdoors. It also can harm vegetation and break down material with rubber compounds.
How is ozone formed?
In basic terms, Hydrocarbons+Nitrogen Oxides+Sunlight=Ozone
Ozone is formed by the action of sunlight on carbon-based chemicals known as hydrocarbons, acting in combination with a group of air pollutants called oxides of nitrogen. Hydrocarbons are emitted by motor vehicles, oil and chemical storage and handling facilities, and a variety of commercial and industrial sources such as gas stations, dry cleaners and degreasing operations. Oxides of nitrogen are a by-produce of burning fuel in sources such as power plants, steel mills and other heavy industry and in motor vehicles.
How does ozone pollution affect people?
Ozone acts as a powerful respiratory irritant at the levels frequently found in most of the nation's urban areas during summer months. Symptoms include shortness of breath, chest pain when inhaling deeply, wheezing and coughing. Tests carried out on healthy adults and children undergoing heavy exercise have found that exposure to ozone at a level equal to the current federal health-based air quality standard of 0.12 parts per million results in a decrease in the normal function of the lungs.
How does ozone pollution affect the environment?
Ozone reacts with vegetation. Ozone may be seen as a haze, which limits visibility.
How can we reduce ozone pollution?
The greatest source of hydrocarbons, one of the precursors to ozone pollution, is the automobile. We can limit these emissions by cutting down on individual driving. We can carpool, van pool, bike, walk or take public transportation. Maine maintains an Ambient State wide M Monitoring Network for ozone violations of the National Standards for ozone have to be documented at various locations throughout the state.
