Alaska

Arizona

Utah

District of Columbia

Florida

Idaho

New Hampshire

Rhode Island

Vermont

Washington

Wyoming

Montana

Maine

North Dakota

Kentucky

Virginia

Delaware

Mississippi

West Virginia

Nebraska

Texas

Missouri

Louisiana

Hawaii

North Carolina

Oregon

Alabama

New Mexico

Kansas

Wisconsin

British Columbia

New Jersey

South Carolina

Michigan

Connecticut

Pennsylvania

Colorado

Nevada

Massachusetts

Georgia

New York

Maryland

Oklahoma

Tennessee

California

Arkansas

South Dakota

Ohio

Indiana

Minnesota

Iowa

Illinois

None

<p>A map shows average tornado incidences per year in the U.S. The highest incidences (dark brown) are in Oklahoma, parts of Texas, Kansas, and Missouri. The lowest incidences (light yellow) are in Alaska, Washington, Oregon, and California.</p>

<p>Tornado prevalence in the United States per 1,000 square miles per year</p>

Average Number of Tornado Incidences per Year (U.S.)

North America

Tornado Archive

Tornadoes per 1,000 square miles per year

Saskatchewan

Manitoba

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:	Average Number of Tornado Incidences per Year (U.S.)					Poor Urban Air Quality
	Less than 1	1–5	6–10	11–15	More than 15	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	99.8%
Utah	100%
District of Columbia		100%
New Hampshire	1.24%	98.7%
Rhode Island		99.3%
Vermont	77.1%	22.6%
Washington	99.9%
Wyoming	87.7%	12.3%
Montana	100%
North Dakota	29.5%	70.5%
Kentucky	4.42%	60.5%	35.1%
Virginia	10.3%	89.6%
Delaware		99.2%
Mississippi		10.9%	74.0%	15.1%
West Virginia	48.2%	51.8%
Nebraska		88.6%	11.4%
Missouri		23.4%	62.5%	14.1%
Hawaii	92.1%
North Carolina		99.9%
Oregon	100%
Alabama		69.5%	16.4%	14.0%
Wisconsin	13.1%	53.1%	33.7%
British Columbia	2.52%
South Carolina		99.9%
Connecticut		99.9%
Pennsylvania	6.15%	93.9%
Massachusetts		99.5%
New York	61.6%	38.3%
Maryland		99.3%
Tennessee		41.3%	58.7%
Arkansas			87.2%	12.8%
South Dakota	22.1%	76.0%	1.85%
Iowa		50.0%	50.0%
Arizona	92.2%	7.76%
Florida		64.2%	35.5%
Idaho	100%
Maine	40.0%	59.8%
Saskatchewan						1
Texas	16.8%	43.9%	36.9%		2.38%		1
Louisiana		30.4%	69.5%
New Mexico	90.2%	9.71%
Kansas		68.1%	31.5%
New Jersey	19.5%	80.3%						1
Michigan	34.8%	64.8%
Colorado	69.4%	30.6%
Nevada	100%
Georgia		61.5%	38.5%
Manitoba
Oklahoma		3.41%	35.1%	46.0%	15.5%
California	99.9%
Ohio	3.97%	96.0%
Indiana		62.9%	37.1%
Minnesota	23.4%	72.5%	4.03%
Illinois		70.3%	29.6%