She sports scars on her wrists and ankle where doctors plunged intravenous needles during frenzied emergency room trips. Right-handed Christine wanted to be sure her good arm was free of needles. Doctors and researchers say the Valley's urbanization, with its air pollution and foreign pollens, eroded any edge the desert gave to asthma sufferers. Allergies cause about 75 percent of asthma. Since 1970, the Valley's population has exploded 330 percent, to 5.1 million.
Urban living puts more people in frequent contact, making it easier for viral infections to spread.
Cramped office workers sit side by side breathing recirculated air. Growing numbers of students share the same class space. And more people and more cars fuel the Valley's Brown Cloud, microscopic specks of dust and soot that lodge in the lungs and complicate breathing. Although state officials have only recently been measuring the haze, they have found that what used to be considered a bad-air day in 1993 had become an average day in 1999. Bob Wininger remembers when it hit him that his young family had not moved to paradise.