PHOENIX (AP) _ From atop Squaw Peak Mountain, Gayle McCann checked out her new hometown. With buildings and mountain peaks obscured by a cafe-au-lait-colored cloud, it was not the crisp desert vista she expected.

``We grew up hearing about Arizona and the air and how people would come here to get over illnesses,'' said the 29-year-old who moved from Minneapolis last fall. ``It kills me to think how much worse the air has gotten out here.''

The days of Phoenix as a clean air haven ended long ago, doomed by the booming development that began after World War II, pollution from cars and trucks and rising humidity from golf courses and endlessly watered lawns.

Still, while the air in Phoenix will never be the same, scientists say it is far cleaner today than it was in the 1960s, when doctors in the East and Midwest began sending patients with arthritis, asthma and other respiratory illnesses to desert cities for the clean, dry air.

Air quality records date only to the 1960s, when 500,000 people called Phoenix home and the air was considered unhealthful more than 100 days each year. Today, there are 2.5 million people, and the bad-air days number in the single digits.

``A lot of air quality is getting better, yet this is a period of incredible growth,'' said Dr. Robert Balling, director of climatology at Arizona State University, who headed a study in the mid-1980s showing that humidity in Phoenix had decreased since 1960. That's because buildings and homes have displaced irrigated fields.

The same trend is true for air quality in other fast-growing Western cities, according to the Environmental Protection Agency. Technological advances in cars and fuels have meant cities like Los Angeles, Phoenix, Albuquerque, Las Vegas and Denver now experience only a fraction of the ``bad air'' days they did in the 1960s and 1970s.

But some air experts say the ability of technology to rein in pollution could be waning. Decades of improvements in the amounts of carbon monoxide, ozone and other pollutants in the air are leveling off, and the air is even getting worse in some cities.

``Areas like San Francisco and L.A. and Phoenix are continuing to grow and sprawl, and we're concerned that technological improvements may be bottoming out and that the curve is starting to go up again,'' said David Howekamp, director of the EPA's air division for California, Arizona, Nevada and Hawaii.

Ozone readings have shot up 11 percent in Phoenix in the last 10 years, and they have either gone up or continued to violate standards in cities like San Diego, Las Vegas and Salem, Ore.

Even if cities are meeting the EPA's health standards, many environmental and health groups _ including the American Lung Association _ wonder whether those yardsticks tell the real story.

``The standards EPA has adopted do not reflect real air quality conditions,'' said David Baron, assistant director of the Arizona Center for Law in the Public Interest. ``In many cases in Phoenix, you'll go outside on a day when the air is visibly filthy and according to the EPA, we're in compliance.''

The focus of the debate on air quality has shifted to growth management to hold down the burgeoning population in the West.

``A lot of those newcomers are the ones pushing the body politic, saying `This is not the quality of life I came here for,''' said David Feuerherd, program director of the Arizona Lung Association.