BOSTON (MainStreet) -- Relocating to one of the communities on a new list of "America's Least Congested Cities" could be a real breath of fresh air for consumers who suffer from allergies or other breathing problems.

"I've been told stories of peoples' lives being infinitely changed for the better by moving to a new city and being able to breathe again," says Bert Sperling of Sperling's Best Places, which recently teamed up with Breathe Right Nasal Strips to compile the list. "Allergies can take a terrible toll on our quality of life."

Sperling analyzed the 50 largest U.S. cities for roughly a dozen congestion-producing factors, from ragweed and ozone levels to wind speed and other climate conditions that spread allergens.

Here's a rundown of the five communities the study found have the least problems with congestion -- along with a look at each city's local economy and housing market.

Home values listed below reflect asking prices on, the National Association of Realtors' official property-listing site. Price ranges refer to all houses, condos and townhouses listed on the site inside a given city and within about 20 miles of its borders.

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Fifth-best city: Seattle

Median list price: $299,950

You'd think a place with so much greenery that it's nicknamed the "Emerald City" would have lots of pollen and mold, but it doesn't.

"Seattle had the lowest overall level of pollens and spores in our study, and low ozone pollution," Sperling says, although he adds that Washington state's largest city does have moderate flu incidence and allergy-medication usage.

The Emerald City is famous for its tech sector, which grew up around locally based Microsoft (MSFT) - Get Report . Other based headquartered in or around Seattle range from (AMZN) - Get Report to Starbucks (SBUX) - Get Report .

(MSFT) - Get Report (AMZN) - Get Report (SBUX) - Get Report Boeing (BA) - Get Report also long called Seattle home, but moved to Chicago last year. The aerospace giant still makes a range of jets at two Seattle-area factories, though.

The 3.4-million-person metro area also hosts the busy port of Seattle, as well as the 42,000-student University of Washington and several smaller schools. lists some 12,500 Seattle-area homes for sale, from a $29,900 one-bedroom condo in the city of Kent to a $26.9 million waterfront estate on tony Mercer Island.

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Fourth-best city: Boston

Median list price: $319,900

The capital of Massachusetts has a low incidence of ozone and flu and slightly below-average pollen.

Sperling says those factors offset above-average levels of smoking and "a climate that can lead to respiratory issues."

In terms of the economy, Beantown hosts several well-known financial, tech and biotech firms, from State Street (STT) - Get Report to Boston Scientific (BSX) - Get Report . The 4.5-million population metro area is also home to Harvard University, the Massachusetts Institute of Technology and other leading schools.

As for housing, there are some 12,100 Greater Boston properties listed for sale on Prices range from $22,900 for a two-bedroom fixer-upper condo in the city of Lowell to $18.8 million for a 13.5-acre estate in the wealthy enclave of Weston.

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Third-best city: Salt Lake City

Median list price: $198,900

"With its dry mountain climate, Salt Lake City has one of the best climates for freedom from respiratory issues," Sperling says.

Utah's capital has the lowest smoking levels of any city studied -- not surprising given the fact that the Mormon faith many residents practice bans tobacco use.

(STT) - Get Report (BSX) - Get Report Salt Lake City also has the second-lowest flu incidence Sperling found, although residents do consume higher-than-average levels of respiratory medicines.

(STT) - Get Report (BSX) - Get Report As for the local economy, Salt Lake City's major businesses include financial firm Zions Bancorp. (ZION) - Get Report and chemical manufacturer Huntsman (HUN) - Get Report (founded by the father of former GOP presidential hopeful Jon Huntsman). Other major local entities include privately held Sinclair Oil and the 23,000-student University of Utah. has some 10,100 Salt Lake City-area properties listed for sale, from a $2,500 two-bedroom Park City, Utah, condo to a $49.5 million 60-acre estate that's also in Park City.

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Second-best city: Miami

Median list price: $265,000

Despite its warm, moist climate, Miami actually has low levels of pollens and air pollution -- probably due to its location along the Atlantic Ocean, Sperling says.

He adds that the city also has low rates of smoking and the flu.

(STT) - Get Report (BSX) - Get Report (ZION) - Get Report (HUN) - Get Report Miami has a widely diversified economy, although it has a heavy emphasis on tourism and businesses catering to Latin American countries and Hispanic-American consumers.

(STT) - Get Report (BSX) - Get Report (ZION) - Get Report (HUN) - Get Report Corporations based in the Miami area range from Royal Caribbean Cruises (RCL) - Get Report to Perry Ellis International (PERY) - Get Report .

The roughly 28,800 Greater Miami properties listed for sale on range from $6,500 for a foreclosed two-bedroom condo in Pompano Beach to $60 million for a 1.8-acre estate on exclusive Indian Creek Island in Biscayne Bay.

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No. 1 least-congested city: San Francisco

Median list price: $599,000

Sperling says San Francisco "takes our top spot for freedom of congestion because ozone pollution is low, pollens are moderate, smoking is low and the use of congestion medications are the lowest for our study. The Mediterranean climate is dry and mild, and even the rate of flu in San Francisco has been well below average in recent years."

The City by the Bay has a diversified economy, with a heavy emphasis on tech and financial firms. Companies that call the San Francisco area home range from search-engine giant Google (GOOG) - Get Report to banking powerhouse Wells Fargo (WFC) - Get Report . The 7.5 million-population metro area also hosts 25,000-student San Francisco State University and several other schools.

As for housing, has some 7,800 San Francisco-area home listings, priced from $30,000 for a one-bedroom home in Richmond, Calif., to $45 million for the newly build Villa Belvedere estate on exclusive Belvedere Island.

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