![[logo] US EPA](https://webarchive.library.unt.edu/eot2008/20081108063330im_/http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Frequent Questions
This page provides commonly asked questions and links to answers. Questions are organized by audience type. If you cannot find the information that you need, please Contact Us.
General Public (including students and teachers)
What is acid rain? What causes it? How is it measured? What does it affect?
Acid rain is a serious environmental problem that affects large parts of the United States and Canada. Acid rain is particularly damaging to lakes, streams, and forests and the plants and animals that live in these ecosystems. Visit EPA’s Acid Rain Web site to find basic information about acid rain and links to educational resources.
Where can I find maps of acid rain?
Visit the National Atmospheric Deposition Program (NADP). 
This network of monitoring sites measures wet deposition, better known as acid rain, and produces maps of pH and other chemical characteristics of rain (e.g., the lower the pH, the more acidic—read more on the pH page). These maps are called isopleth maps.
What can I do to help reduce/mitigate acid rain?
There are several ways to reduce acid rain—more properly called acid deposition—ranging from societal changes to individual action. Visit the Reducing Acid Rain page.
How does allowance trading work?
EPA’s Clean Air Markets Programs use a market-based regulatory program called “cap and trade” to regulate emissions and improve air quality. Visit the Allowance Trading Basics page.
How can my students or I buy SO2 allowances so they won't be emitted?
Under the Acid Rain Program and the NOx Budget Trading Program, anyone can trade allowances, including members of the general public without any affiliation with a regulated source. Some individuals and groups purchase allowances as an environmental statement, because withholding allowances from the market prevents those allowances from being used by utilities.
For more information, visit the Other Market Participants page.
Do you have experiments for students to learn more about acid rain?
Yes! Visit Acid Rain Educational Resources for science experiments related to acid rain.
Do you have suggestions for activities, both inside the classroom and out?
Yes! Visit Acid Rain Educational Resourcesfor learning activities related to acid rain.
How much sulfur dioxide (SO2), nitrogen oxides (NOx), and other gases do electric power plants emit (i.e., release) into the atmosphere?
Visit our Data and Maps Web site to view charts, maps, and data. The Emissions Wizard Tool provides facility and unit emissions data.
Academic Researchers
What is acid rain and what are its effects?
Visit EPA’s Acid Rain Web site to find basic information about acid rain including links to additional information on state and national data and statistics, acid rain legislation, and U.S. and international initiatives.
Where can I find academic papers and more detailed articles?
Visit our Resource Center and Progress and Results page.
How does allowance trading work?
EPA’s Clean Air Markets Programs use a market-based regulatory program called “cap and trade” to regulate emissions and improve air quality. Visit the Allowance Trading Basics page.
How does EPA keep track of who owns what allowances?
Visit EPA’s Allowance Trading page for more information.
How do I find information about allowance accounts, how many allowances they hold, and allowance trades?
Visit our Data and Maps Web site. The Allowances Wizard Tool provides account and allowance data.
What are the emissions from power plants?
Visit ourData and Maps Web site to view charts, maps, and data. The Emissions Wizard Tool provides facility and unit emissions data. Also visit EPA’s eGRID system—a comprehensive source of data on the environmental characteristics of almost all electric power generated in the U.S.
Are companies complying with the regulatory programs?
EPA publishes several Progress Reports summarizing the progress made towards achieving compliance and the goals of the Clean Air Markets Programs.
How do EPA’s Clean Air Market Programs work?
Clean air markets include various market-based regulatory programs designed to improve air quality. These programs focus on lowering outdoor concentrations of fine particles, mercury, ozone, and other significant air emissions. The most well-known of these programs are EPA’s Acid Rain Program and the NOx Trading Programs, which reduce emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx)–compounds produced by fossil fuel combustion.
Utilities
Where can I find the regulations that apply to each program?
Visit EPA’s Programs and Regulations page for more information.
How do I query the allowance tracking system?
Visit our Data and Maps Web site. The Allowances Wizard Tool provides account and allowance data.
What is necessary to comply with a program?
Visit the Doing Business with Us—Industry page to learn more.
How do I sign up to participate in a program?
Any person, company, or organization that wants to trade allowances must register to do so.
Where can I find forms for each program?
Generally, it's best to read about a particular activity—transferring allowances, reporting emissions, completing annual reconciliation, etc.—forms will be linked from there. Start with the Doing Business with Us—Industry page. However, if you know the specific form you need, visit our Forms page.
How do I keep up with monitoring requirements?
EPA’s emissions monitoring requirements ensure that the emissions data collected is of a known, consistent, and high quality, and that the mass emissions data from source to source are collected in an equitable manner. Visit the Emissions Monitoring page to learn more.
How do I keep up with emissions reporting requirements?
Regulated sources must report all emissions as measured by continuous emissions monitors. EPA has established standard reporting procedures, and has developed standardized software for such reporting. Visit the Report Emissions page to learn more.