How Does Air Pollution Effect the Environment?
Pollutants in the air, deposited on soils or surface waters, can have a variety of environmental impacts. Like humans, animals and plants can experience health problems if they are exposed to sufficient concentrations of air pollution over time.

Effects on Vegetation
Acid rain does not usually kill trees directly. Instead, it is more likely to weaken trees by damaging their leaves, thereby limiting the nutrients available to them. This loss of nutrients in their foliage makes trees more susceptible to damage by other environmental factors, particularly cold winter weather. Acid rain can harm other plants in the same way it harms trees. Farmers frequently add fertilizers to the soil to replace nutrients to lessen the effects of acid rain.

The experiments in this lesson will visually demonstrate a significant change in pH levels. This is done purposely to demonstrate the possibilities of pH level change caused by acid rain. It would be beneficial to explain to students that there are natural materials and added materials to the soil that can help to lessen the impact of acid rain in the environment.

Effects on Water
Pure water has a pH of 7.0. Normal rain is slightly acidic with a pH of about 5.5. As of the year 2000, the most acidic rain falling in the U.S. had a pH of about 4.3.

Of the lakes and streams surveyed in a National Surface Water Survey (NSWS), acid rain caused acidity in 75 percent of the acidic lakes and about 50 percent of the acidic streams. One of the most acidic lakes reported is Little Echo Pond in Franklin, New York. Little Echo Pond has a pH of 4.2.
Streams flowing over soil are as susceptible to damage from acid rain as lakes. Approximately 580 of the streams in the Mid-Atlantic Coastal Plain and over 1,350 of the streams in the Mid-Atlantic Highlands (mid-Appalachia) are acidic, primarily due to acidic deposition.

The experiments in this lesson will visually demonstrate a significant change in pH levels. This is done purposely to demonstrate the possibilities of pH level change caused by acid rain. It would be beneficial to explain to students that there are natural materials in the water and soil that can help to lessen the impact of acid rain in the environment.

It may be helpful to review or complete the following activity, Sense of Scale, before performing the experiment in this lesson.

Effects on Visibility
Haze is caused by fine particles that scatter and absorb light before it reaches the observer. As the number of fine particles increases, more light is absorbed and scattered, resulting in less clarity, color, and visual range. Sulfates and nitrates that form in the atmosphere from sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions contribute to visibility impairment, meaning we can't see as far or as clearly through the air. Sulfate particles account for 50 to 70 percent of the visibility reduction in the eastern part of the United States, affecting our enjoyment of national parks, such as the Shenandoah and the Great Smoky Mountains. In the western part of the United States, nitrates and carbon also play roles, but sulfates have been implicated as an important source of visibility impairment in many of the Colorado River Plateau national parks, including the Grand Canyon, Canyonlands, and Bryce Canyon.

Effects on Materials
Acid rain and the dry deposition contribute to the corrosion of metals and the deterioration of paint and stone (such as marble and limestone). These effects seriously reduce the value to society of buildings, bridges, cultural objects (such as statues, monuments, and tombstones), and cars. Dry deposition of acidic compounds can also dirty buildings and other structures, leading to increased maintenance costs.


How Are People Exposed to Air Pollution?
People are exposed to air pollutants in many ways that can pose health risks, such as:

• Breathing contaminated air.
• Eating contaminated food products, such as fish from contaminated waters.

People who are exposed to air pollutants at sufficient concentrations and for sufficient durations may increase their chances of experiencing serious health effects. For instance, many scientific studies have linked breathing particulate matter to a series of significant health problems, including:

• cardio-vascular disease
• aggravated asthma
• increases in respiratory symptoms like coughing and difficult or painful breathing
• chronic bronchitis
• decreased lung function

Testing for pH
A variety of water and soil testing kits, meters and papers are available from just about any science catalog (i.e. Sargent-Welsh, Frey Scientific, PASCO, Boreal/Science Kit and many others - look in the Environmental Science section.) Kits are also available from suppliers such as LaMotte, Hach, and Chemetrics, all specialize in this type of equipment. The test kits range quite a bit in cost and complexity and you should determine what is most appropriate for your students and budget.

Web sites for some of the suppliers are shown below:

• LaMotte Education and Outdoor Monitoring
• Hach Water Testing Kits
• Chemetrics Water Testing Kits

Using microcomputer based labs (probes) are an alternative to testing kits. Using a variety of sensors and software, labs can be designed to examine pH, etc.:

• PASCO scientific
  • PASCO water quality probes
• Vernier

Print... | Close