Arizona

Utah

Idaho

Wyoming

Montana

Texas

Missouri

Oregon

New Mexico

Nevada

California

None

A world map shows nitrate mining locations marked by orange circles with "N." Key areas include the U S, Mexico, Chile, and Spain. Major clusters are in the U S (western states), Mexico, and northern Chile's Atacama Desert.

Nitrate Mines

World

USGS

Alaska

Yukon

Northwest Territories

District of Columbia

Florida

New Hampshire

Rhode Island

Vermont

Washington

Nunavut

Maine

North Dakota

Kentucky

Nova Scotia

Virginia

Delaware

Prince Edward Island

Saskatchewan

Mississippi

West Virginia

Nebraska

Louisiana

North Carolina

New Brunswick

Alabama

Kansas

Wisconsin

British Columbia

Newfoundland and Labrador

New Jersey

South Carolina

Michigan

Alberta

Connecticut

Pennsylvania

Colorado

Massachusetts

Georgia

New York

Maryland

Québec

Manitoba

Oklahoma

Tennessee

Ontario

Arkansas

South Dakota

Ohio

Indiana

Minnesota

Iowa

Illinois

A map of North America shows various ecological regions, each marked with a distinct color to represent different Level 1 ecological regions.

Extent of the Level I Ecological Regions of North America

Ecological Regions: Level 1 Regions

Arctic Cordillera (Red): Found in the northernmost parts of Canada, specifically the Arctic Archipelago. Tundra (Blue): Covers large portions of northern Canada, including parts of Nunavut and the Northwest Territories, as well as coastal areas of Alaska. Taiga (Purple): Spans across central and northern Canada, covering parts of Quebec, Ontario, Manitoba, Saskatchewan, Alberta, and British Columbia. Hudson Plain (Orange): Located in the northeastern part of Canada, around the Hudson Bay area. Boreal Forests (Yellow): Encompasses large areas in Canada, south of the tundra and taiga regions, and extends into parts of Newfoundland and Labrador. Northwestern Forested Mountains (Green): Found along the western coast of Canada and the United States, covering parts of British Columbia and Alaska. Marine West Coast Forest (Brown): Occupies the coastal regions of the Pacific Northwest, including areas in British Columbia, Washington, Oregon, and northern California. Eastern Temperate Forests (Pink): Stretch from the Great Lakes region through the northeastern United States and into eastern Canada. Great Plains (Grey): Span the central United States from Canada to Texas, including parts of Alberta, Saskatchewan, Manitoba, and several central U.S. states. Deserts and Steppes (Dark Green): Found in the southwestern United States and northern Mexico, covering areas in Arizona, New Mexico, and parts of California and Nevada. Mediterranean California (Dark Pink): Specific to the coastal regions of central and southern California. Southern Semi-Arid Highlands (Gold): Located in central Mexico and parts of the southwestern United States. Temperate Sierras (Dark Brown): Found in Mexico, primarily in the Sierra Madre ranges. Tropical Dry Forests (Light Brown): Present in parts of southern Mexico and Central America. Tropical Wet Forests (Light Tan): Located in the southeastern part of Mexico and Central America, including the Yucatan Peninsula.

North America

The map shows urban air quality in terms of micrograms of particulate matter per cubic meter of air. For the purposes of this description, the five categories on the map are simplified to less 80 micrograms per cubic meter; between 80 and 200 micrograms per cubic meter; and more than 200 micrograms per cubic meter. In North America, there are several areas with multiple locations where air quality is less than 80 micrograms: in Canada, near Vancouver, British Columbia; in Alberta; and in southern Ontario and Quebec near the Great Lakes and St. Lawrence River. In the United States, areas with air pollution in this range occur in mainly in California and in the Midwest and Northeast. A few scattered locations in Mexico, Central America, and the Caribbean (Jamaica) also have pollution in this range. In South America, air quality less than 80 micrograms per cubic meter occurs in widely scattered locations, such as Caracas, Venezuela; Colombia; Ecuador; Bolivia; northern and central Chile; Buenos Aires, Argentina; and north of Rio de Janeiro, Brazil. Most of Western and Central Europe have air pollution of less than 80 micrograms per cubic meter. Exceptions include Ireland, Portugal, and Scandinavia. (In Russia, air pollution is at this level in Moscow, but east of the Urals in Siberia, there are also sites that are more polluted—between 80 and 200 micrograms. Africa has relatively little air pollution of this type, areas less than 80 micrograms include Liberia, Tanzania, Madagascar, and South Africa (the area around Johannesburg). In Southwest Asia, Turkey, Lebanon, Israel, and Cyprus have multiple sites less than 80 micrograms per cubic meter. However, Iran and the Persian Gulf states (Bahrain, Qatar, the United Arab Emirates) have multiple sites between 80 and 200 micrograms, and Iraq and Bahrain have sites that are higher than 200 micrograms. Apart from Kabul, Afghanistan, which is higher than 200 micrograms per cubic meter, there are no countries in Central Asia that have poor urban air quality according to the criteria used here. In northern Pakistan, India, and Bangladesh, there are cities with poor urban air quality—ranging from 80 to more than 200 micrograms per cubic meter. In southern India, Sri Lanka, and Nepal, pollution levels range from below 80 up to 200 micrograms per cubic meter. In Southeast Asia, pollution in Myanmar, Thailand, Laos, Vietnam, and Indonesia is generally less than 80 micrograms, except in the northern Philippines, where it is between 80 and 200. In the cities of southern and western China, pollution is less than 80 micrograms per cubic meter, except in far western Urumqi, which is between 80 and 200 micrograms. In eastern and northern China urban air pollution increases to between 80 and 200 micrograms. Mongolia has a few locations less than 80 micrograms per cubic meter and others between 80 and 200 micrograms. South Korea has numerous cities with pollution less than 80, whereas in Japan, Tokyo is the only city in this category. In Oceania, only New Zealand is identified as having poor urban air quality, with two locations on the South Island less than 80 micrograms per cubic meter.

Ambient (outdoor) air pollution levels represented by annual mean concentration of particulate matter smaller than 10 (PM₁₀), for cities of the world with more than 100,000 inhabitants

Display by:	Nitrate Mines	Ecological Regions: Level 1 Regions														Poor Urban Air Quality
	Nitrate Mines	Arctic Cordillera	Tundra	Taiga	Hudson Plain	Boreal forests	Northwestern forested mountains	Marine west coast forest	Eastern temperate forests	Great Plains	Deserts and steppes	Mediterranean California	Southern semi-arid highlands	Temperate sierras	Tropical wet forests	Regina	Houston	Philadelphia	Oklahoma City	San Antonio	Boulder	Wichita	Portland	Irvine	Minneapolis	Boise	Winnipeg	Spring Hill	Greeley	St. Louis	Detroit	West Palm Beach	Columbus	Augusta	McAllen	Topeka	Las Cruces	Bakersfield	Oceanside	Reno	Indianapolis	Stockton	Baton Rouge	Glendale	Salinas	Trenton	Aurora	Modesto	Nogales	Rock Island	Fresno	Covington
Alaska			25.1%	6.23%			14.3%	3.61%
Utah	4						19.3%				80.3%
Yukon			7.08%	38.7%			53.4%
Northwest Territories			3.04%	63.7%
District of Columbia									100%
New Hampshire						82.5%			17.5%
Rhode Island									92.1%
Vermont						86.9%			13.1%
Washington							44.1%	18.2%			34.8%
Wyoming	1						6.11%			27.1%	46.4%
Nunavut		1.96%	1.52%	3.41%
Montana	2						31.6%			66.0%
North Dakota										100%
Kentucky									100%
Nova Scotia						17.5%			6.61%
Virginia									99.4%
Delaware									98.4%
Prince Edward Island									89.2%
Mississippi									99.9%
West Virginia									100%
Nebraska										100%
Missouri	1								60.6%	39.4%
North Carolina									99.2%
Oregon	3						53.3%	14.9%			7.11%
New Brunswick						3.19%			95.8%
Alabama									99.9%
Wisconsin						31.7%			66.5%	1.10%
British Columbia				7.72%		4.25%	60.9%	6.59%			4.95%
Newfoundland and Labrador			5.23%	56.9%		22.4%
South Carolina									99.7%
Alberta				17.4%		54.4%	6.61%			21.1%
Connecticut						15.9%			84.0%
Pennsylvania						3.06%			79.4%
Massachusetts						32.4%			63.3%
New York						19.7%			1.05%
Maryland									97.9%
Québec			1.01%	37.0%	2.25%	3.73%			1.51%
Tennessee									100%
Ontario					28.1%	64.1%			7.08%
Arkansas									100%
South Dakota							3.94%			96.1%
Iowa									6.36%	93.6%
Arizona	2										66.3%		12.9%	19.7%
Florida									84.3%						14.5%
Idaho	2						57.3%				40.7%
Maine						44.1%			52.2%
Saskatchewan				8.06%		57.8%				33.4%						1
Texas	6								17.3%	4.05%	13.1%						1
Louisiana									86.4%	12.6%
New Mexico	1						8.59%			32.9%	7.36%		1.32%	3.54%
Kansas										99.9%
New Jersey						11.2%			86.6%									1
Michigan						25.2%			1.08%
Colorado							38.2%			42.1%	2.98%
Nevada	1										99.6%
Georgia									99.9%
Manitoba				22.1%	11.3%	55.4%				10.0%
Oklahoma									21.6%	78.4%
California	3						26.9%	2.89%			29.8%	39.7%
Ohio									99.9%
Indiana									100%
Minnesota						40.6%			24.1%	35.2%
Illinois									99.9%