Editing Acid rain (section)

==Prevention methods==

===Technical solutions===
Many coal-firing [[power station]]s use [[flue-gas desulfurization]] (FGD) to remove sulfur-containing gases from their stack gases. For a typical [[coal-fired power station]], FGD will remove 95% or more of the SO<sub>2</sub> in the flue gases. An example of FGD is the [[wet scrubber]] which is commonly used. A wet scrubber is basically a reaction tower equipped with a fan that extracts hot smoke stack gases from a power plant into the tower. Lime or limestone in slurry form is also injected into the tower to mix with the stack gases and combine with the sulfur dioxide present. The calcium carbonate of the limestone produces pH-neutral [[calcium sulfate]] that is physically removed from the scrubber. That is, the scrubber turns sulfur pollution into industrial sulfates.

In some areas the sulfates are sold to chemical companies as [[gypsum]] when the purity of calcium sulfate is high. In others, they are placed in [[landfill]]. The effects of acid rain can last for generations, as the effects of pH level change can stimulate the continued leaching of undesirable chemicals into otherwise pristine water sources, killing off vulnerable insect and fish species and blocking efforts to [[Restoration ecology|restore]] native life.

[[Fluidized bed combustion]] also reduces the amount of sulfur emitted by power production.

[[Vehicle emissions control]] reduces emissions of nitrogen oxides from motor vehicles.

===International treaties===
[[File:Acid Rain box -  23 (49753937638).jpg|thumb|Governmental action to combat the effects of acid rain]]
International treaties on the long-range transport of atmospheric pollutants have been agreed upon by western countries for some time now. Beginning in 1979, European countries convened in order to ratify general principles discussed during the UNECE Convention. The purpose was to combat Long-Range Transboundary Air Pollution.<ref>{{Cite web|title=The Convention and its achievements {{!}} UNECE|url=https://unece.org/convention-and-its-achievements|access-date=2021-10-22|website=unece.org}}</ref> The [[1985 Helsinki Protocol on the Reduction of Sulfur Emissions]] under the [[Convention on Long-Range Transboundary Air Pollution]] furthered the results of the convention. Results of the treaty have already come to fruition, as evidenced by an approximate 40 percent drop in particulate matter in North America.<ref>{{Cite web|last1=Moses|first1=Elizabeth|last2=Cardenas|first2=Beatriz|last3=Seddon|first3=Jessica|date=February 25, 2020|title=The Most Successful Air Pollution Treaty You've Never Heard Of|url=https://www.wri.org/insights/most-successful-air-pollution-treaty-youve-never-heard}}</ref> The effectiveness of the Convention in combatting acid rain has inspired further acts of international commitment to prevent the proliferation of particulate matter. Canada and the US signed the [[Air Quality Agreement]] in 1991. Most European countries and Canada signed the treaties. Activity of the Long-Range Transboundary Air Pollution Convention remained dormant after 1999, when 27 countries convened to further reduce the effects of acid rain.<ref>{{Cite web|title=International Agreements on Acid Rain|url=http://www.enviropedia.org.uk/Acid_Rain/International_Agreements.php|access-date=2021-10-22|website=enviropedia.org.uk|archive-date=October 22, 2021|archive-url=https://web.archive.org/web/20211022013359/http://www.enviropedia.org.uk/Acid_Rain/International_Agreements.php|url-status=dead}}</ref> In 2000, foreign cooperation to prevent acid rain was sparked in Asia for the first time. Ten diplomats from countries ranging throughout the continent convened to discuss ways to prevent acid rain.<ref>{{Cite web|date=October 26, 2000|title=Talks start to form network to monitor Asia's acid rain|url=https://www.japantimes.co.jp/news/2000/10/26/national/talks-start-to-form-network-to-monitor-asias-acid-rain/|access-date=2021-10-22|website=The Japan Times}}</ref> Following these discussions, the Acid Deposition Monitoring Network in East Asia (EANET) was established in 2001 as an intergovernmental initiative to provide science-based inputs for decision makers and promote international cooperation on acid deposition in East Asia.<ref>{{cite journal |last1=Totsuka |first1=Tsumugu |last2=Sase |first2=Hiroyuki |last3=Shimizu |first3=Hideyuki |title=Major activities of acid deposition monitoring network in East Asia (EANET) and related studies |journal=Plant Responses to Air Pollution and Global Change |date=2005 |pages=251–259 |doi=10.1007/4-431-31014-2_28 |isbn=978-4-431-31013-6 }}</ref> In 2023, the EANET member countries include Cambodia, China, Indonesia, Japan, Lao PDR, Malaysia, Mongolia, Myanmar, the Philippines, Republic of Korea, Russia, Thailand and Vietnam.<ref>"EANET National Focal Points" https://www.eanet.asia/about/national-focal-points/ retrieved February 16, 2023.</ref>

===Emissions trading===
{{main|Emissions trading}}
{{See also|Acid Rain Program}}
In this regulatory scheme, every current polluting facility is given or may purchase on an open market an emissions allowance for each unit of a designated pollutant it emits. Operators can then install pollution control equipment, and sell portions of their emissions allowances they no longer need for their own operations, thereby recovering some of the capital cost of their investment in such equipment. The intention is to give operators economic incentives to install pollution controls.

The first emissions trading market was established in the United States by enactment of the [[Clean Air Act (United States)|Clean Air Act Amendments of 1990]].<ref>Former Deputy Administrator Hank Habicht talks about management at EPA. An Interview with Hank Habicht [http://www.epaalumni.org/history/video/interview.cfm?id=17 Video], [https://www.epaalumni.org/userdata/pdf/60772C611F145A4D.pdf#page=6 Transcript] {{Webarchive|url=https://web.archive.org/web/20190412070307/https://www.epaalumni.org/userdata/pdf/60772C611F145A4D.pdf#page=6 |date=April 12, 2019 }} (see p6). December 21, 2012.</ref> The overall goal of the Acid Rain Program established by the Act<ref>Clean Air Act Amendments of 1990, 42 ''U.S. Code'' [https://www.govinfo.gov/content/pkg/USCODE-2011-title42/html/USCODE-2011-title42-chap85-subchapIV-A-sec7651.htm 7651] {{Webarchive|url=https://web.archive.org/web/20210328121224/https://www.govinfo.gov/content/pkg/USCODE-2011-title42/html/USCODE-2011-title42-chap85-subchapIV-A-sec7651.htm |date=March 28, 2021 }}</ref> is to achieve significant environmental and public health benefits through reductions in emissions of sulfur dioxide (SO<sub>2</sub>) and nitrogen oxides (NO<sub>x</sub>), the primary causes of acid rain. To achieve this goal at the lowest cost to society, the program employs both regulatory and market based approaches for controlling air pollution.