According to a recently published World Health Organization (WHO) study, 亚洲天堂 Lake has some of the best air in the world.

Whitehorse, Yukon, came out on the top of WHO's worldwide air quality list, with three micrograms of particulate matter per cubic metre.

Not far behind, Kitimat is second with four micrograms of particulate matter per cubic metre, and 亚洲天堂 Lake and Houston both measured five micrograms of particulate matter per cubic metre.

WHO's study includes data from nearly 1,100 cities and towns across 91 countries.

The data is based on measurements taken worldwide from 2003 to 2010, with the great majority being reported for the period between 2008 and 2009

WHO reports that in many cities, air pollution is reaching levels that threaten human health. They estimate that more than two million people die every year from breathing in tiny particles present in indoor and outdoor air pollution.

PM10 particles, which are particles 10 micrometers or less in size, can penetrate into the lungs and may enter the bloodstream. The particulates can cause heart disease, lung cancer, asthma and acute lower respiratory infections.

WHO air quality guidelines for PM10 allow for 20 micrograms per cubic metre as an annual average, but the study findings show that average PM10 in some cities has reached up to 300 micrograms per cubic metre.

WHO reports that B.C. cities and towns have some of the cleanest air on earth.

British Columbia had the cleanest air in six of the top 10 cities in the world, including Kitimat, 亚洲天堂 Lake, Houston, Terrace, Nanaimo and Nelson.

According to the study, the worst air quality in the world exists in Ulaanbaatar, Mongolia.

Air quality measurements (taken in 2008) report that Ulaanbaatar citizens are subjected to an average of 63 micrograms of particulate matter per cubic metre.

Kuwait City, in Kuwait, with a population of more than 2.3 million, Mexicali, Baja, Mexico with a population of almost one million people and Accra the capital and largest city in Ghana with a population of more than 1.6 million also have some of the worlds worst air. All range in the region of 50 micrograms of particulate matter per cubic metre.

Amongst countries, Estonia topped the list with the best air quality, Mauritius ranked second, while Australia and Canada tied for third.

WHO say that persistently elevated levels of fine particle pollution are common across many urban areas as fine particle pollution often originates from combustion sources such as power plants and motor vehicles.

"Air pollution is a major environmental health issue and it is vital that we increase efforts to reduce the health burden it creates," said Dr. Maria Neira, WHO director for public health and environment.

"If we monitor and manage the environment properly we can significantly reduce the number of people suffering from respiratory and heart disease and lung cancer. Across the world, city air is often thick with exhaust fumes, factory smoke or soot from coal burning power plants. In many countries there are no air quality regulations and where they do exist, national standards and their enforcement vary markedly," she said.

WHO is now calling for greater awareness of health risks caused by urban air pollution, implementation of effective policies and close monitoring of the situation and hopes the study will be used by cities to monitor trends in air pollution as well as to improve and up scale intervention efforts.

Canadian cities and towns by micrograms of particulate matter per cubic metre; Whitehorse, 3, Kitimat, 4, 亚洲天堂 Lake and Houston, 5, Terrace, Nanaimo, Nelson, Medicine Hat, Fredericton and Corner Brook all with 6, Victoria: 7, Vancouver and Halifax, 8, Ottawa, Calgary and Regina, 9, Moncton 10, Edmonton 11, Toronto, 13 and Montreal, 19.

To view the full report go to www.who.int/en.