Pittsburgh residents preparing to burst out the door for a jog or bike ride might want to consider the latest warning from Men's Health magazine.

The July/August edition now on newsstands says Pittsburgh earns an F and ranks 98 among 100 American cities for poor air quality.

Although no longer the smoky city, Pittsburgh continues to have serious air quality issues, the magazine notes.

Men's Health, with a circulation of about 1.7 million, ranked Los Angeles, Philadelphia and Cleveland higher in air quality than Pittsburgh, where heavy traffic congestion, high levels of particulate matter from coal-fired power plants and a generally unfavorable Air Quality Index sealed its fate.

The Air Quality Index represents a "chemical snapshot" of five pollutants: ozone, sulfur dioxide, nitrogen oxide, carbon monoxide and particulate pollution.

"One thing that pulled it down was traffic congestion," said Matt Marion, the magazine's features editor. "The Texas Transportation Institute's Travel Time Index ranked Pittsburgh in the bottom 20 percent of cities evaluated. Relative to other cities, Pittsburgh had a higher traffic-congestion rate."

When traffic is congested, vehicles spew exhaust into the atmosphere, he said.

"Congestion infers more pollution, and from its Air Quality Index rating, in fact that's the case," Mr. Marion said.

The top-ranked cities were, in order, Honolulu; Fargo, N.D.; Lincoln, Neb.; Corpus Christi, Texas; Fremont, Calif.; Cheyenne, Wyo.; Lubbock, Texas; Denver and Anchorage, Alaska.

Cleveland received a B- and was ranked 32nd. Philadelphia came in 67th.

The only two major American cities to rank lower than Pittsburgh were Chicago and 100th-ranked Detroit.

Detroit had the highest asthma rate of all major cities and is second lowest in the number of good air-quality days each year, with a high number of unhealthy air-quality days.

Pittsburgh had 121 bad air-quality days of 305 total days measured, which put it near the bottom of the list of cities, Mr. Marion said. Compare that with Honolulu, which had but three bad days of 174 days measured in 2005.

Pittsburgh also had seven days in 2005 when its air was too unhealthy to breathe. Compare that with smog-capital Los Angeles, which had 10 unhealthy days.

"The problem with air pollution is that it isn't always visible," Mr. Marion said of Pittsburgh. "Air can look fine, but there can be enough different pollutants in it to make the score go down."

A magazine news release states that millions of people who run and cycle to improve their health and fitness "may very well be speeding toward an early grave" in cities like Pittsburgh.

"Recent research conducted in Finland shows a clear connection between dirty air and heart-attack risk," the release states. "Results linked particle pollution with a threefold increase in the risk of ischemia, a potentially lethal shortage of oxygen reaching the heart muscle."

But Kurt Knaus, press secretary for the state Department of Environmental Protection, said he does not think Pittsburgh deserves an F from Men's Health.

"It's come a long way," he said. "People with ranking systems perpetuate the image of Pittsburgh being a smoke-filled city. That's disappointing, but that being said, everyone still understands because of its geographic location Pittsburgh has air-quality challenges that are not from within its own borders."

Pittsburgh and southwestern Pennsylvania do not meet federal standards for particle pollution and ozone, he said.

Although much has been done to improve air quality in the city, problems continue because of its geographic location.

"As much as has been done, you still find poor air quality and one reason is Pittsburgh sits in the valley to the east of the Midwestern power plants and in direct path of prevailing winds from those power generators," he said.

"Southwestern Pennsylvania always has been plagued by issues of air quality related to problems beyond its borders," Mr. Knaus said.

What is necessary, he said, is federal programs to limit pollution that crosses state boundaries.

The city's high levels of traffic congestion result from lifestyle choices, Mr. Knaus said. People move ever farther from the city but continue to commute.

"People are driving more today than ever," he said.